Chapter 1Introduction

1

1. IntroductionThis report provides a comprehensive review of the current research activities that focus on the ZnO based materials and their physical property and Characterizations. It begins with the different methods that have been exploited to grow ZnO thin films. A range of remarkable characteristics are then presented, organized into sections describing the electrical, magnetic and chemical sensing properties. These studies constitute the basis for developing versatile applications of ZnO nanostructures. The attraction can simply be attributed to the large exciton binding energy of 60 meV of ZnO potentially paving the way for efficient room-temperature exciton-based emitters, and sharp transitions facilitating very low threshold semiconductor lasers. The field is also fueled by theoretical predictions and perhaps experimental confirmation of ferromagnetism at room temperature for potential spintronics applications. This review gives an in-depth discussion of the physical, chemical and electrical properties of ZnO in addition to the technological issues such as growth. ZnO is not really a newly discovered material. Research on ZnO has continued for many decades with interest following a roller-coaster pattern. Interest in this material at the time of this writing is again at a high point. ZnO is easily etched in all acids and alkalis, and this provides an opportunity for fabrication of small-size devices. In addition, ZnO has the same crystal structure. In this paper we collate the properties of ZnO as well as review the recent progress in ZnO research. This present review is distinguishable from the other reviews which is focused mainly on material processing, doping, and transport properties. In recent years there has been an extensive research towards introducing ferromagnetic property at room temperature in semiconductors to realize a new class of spintronic devices such as spin valves, transistors, spins light emitting diodes, magnetic sensors, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches. The potential advantages of spintronic devices will be higher speed, greater efficiency, and better2

stability, in addition to the low energy required to flip a spin. A ZnO based DMS would be very promising because of its widespread applications in electronic devices, such as transparent conductors, gas sensors, varistors, surface acoustic wave devices, optical wave guides, acousto-optic modulators/deflectors, ultra violet laser source, and detectors. Despite uncertainty in the mechanism of ferromagnetism in doped semiconductors, and the fact that the obtained magnetization is lower than the theoretically predicted value in most of the reports appearing in literature, the results reported thus far, provide a pathway for exploring the transition metal doped DMS. It is however, imperative to understand the phenomenon and the factors affecting the magnetization value in order to realize commercially applicable devices.

The main aim of the present thesis is to show that it is indeed possible to obtain room temperature ferromagnetic semiconductors by controlling the process parameters. Theoretical prediction of room temperature ferromagnetism in transition metal doped ZnO could be realized experimentally. It is shown that the properties of precursors used for making of DMS have a great influence on the final properties of the material. Use of various experimental techniques to verify the physical properties, and to understand the mechanism is demonstrated. Methods to improve the magnetic moment are also described.

3

ORGANIZATION OF THESISAfter giving the brief introduction about the spintronic devices, now work has been focused on ZnO thin film based samples deposited by CWD (Chemically Wet and Dry) technique. ZnO based semiconductor films are deposited on to the glass, silver, copper, aluminum substrates using CWD technique. The deposited films are characterized using X-Ray Diffraction (XRD), Four-probe method, Hotprobe method, and Hall Effect. The remaining part of the thesis is organized in the following manner:

Chapter-2:- Literature review. Chapter-3:- Spintronic devices and semiconductors materials. Chapter-4:- Experimental works. Chapter-5:- Results and analysis. Chapter-6:- Conclusion and scope for further work.

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Chapter-2Literature review

5

Literature review has been carried out in view of my project work. The project is focused on ZnO and transition metal doped ZnO thin film based samples deposited by CWD (Chemically Wet and Dry) technique on different types of conducting and non conducting substrates. In the following sections review of literature has been reported. Dr. E. SENTHIL KUMAR who got his doctor of philosophy from IIT, Madras has out lined a thisis about ZnO based thin films, nanostructures and hetro structures for optoelectronics and spintronic applications in the year 2010 has followed in this report. Dr. Wei Guo and got his PHD from University of Michigan has presented a work over Epitaxial growth and properties of zinc oxide thin films on silicon substrates in the year 2010 were studied. Transition metal implanted ZnO:a correlation between structure and magnetism is a report which was presented by Doctor Shengqiang Zhou, Doctor rerum naturalium , Prof. Dr. Manfred Helm. Prof. along with oter group members of Institute of structural physics and Material Science Dresden-Rossendorf in the year 2007 . Dr Ngwashi Divine Khan who has got his doctorate degree from De Montfort University has a deep investigation of the Performance and Stability of Zinc Oxide Thin-film Transistors and the Role of High-k Dielectrics in the year 2010 which has a very important application in this field Fe implanted ferromagnetic ZnO. which was published in Appl. Phys. Lett., 88:052508, 2006 by the authors K. Potzger, S. Q. Zhou, H. Reuther, A. Mcklich, F. Eichhorn and co. Microstructure and electronic structure of transparent ferromagnetic ZnO-Spinel iron oxide composite films was published Chem. Mater., 18:763770, 2006 by T. Shinagawa, M. Izaki, H. Inui, K. Murase etc. and carried out a results about the ZnO thin films magnetic properties.

6

Chapter-3Spintronic devices and semiconductor materials.

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3.1 Spintronic devices

Spintronic devices came into action after the discovery of powerful effect called Giant magneto resistance (GMR) in 1988 by French and German physicists . It results from subtle electron-spin effects in ultra-thin 'multilayer' of magnetic materials, which cause huge changes in their electrical resistance when a magnetic field is applied. It is a sandwich structure with alternating layers of magnetic and nonmagnetic metal (Fig-1). Depending upon the relative orientations of the magnetizations in the magnetic layers, the electrical resistance changes from small (parallel magnetizations) to large (antiparallel magnetizations). The magnitude of this change is two order of magnitude larger than is possible with conventional materials, hence the name giant magneto resistance.

Fig-1 A GMR sandwich structure. Consisting of alternating magnetic and nonmagnetic metal layers.

Physicists have been quick to see the further possibilities of spin valves. Not only they are highly sensitive magnetic field sensors, they can also be made to act as switches by flipping the magnetization in one of the layers. This allows information to be stored as 0s and 1s8

(magnetizations of the layers parallel or antiparallel) conventional transistor memory device.

as in a

MRAM is rapidly developing as a technology because it can allow quantum computing by use of spin of individual particles to process information. Such an information bearing particle is known as a quantum bit or qubit. It is amazing to know that only 34 qubits are required to represent the total amount of information stored in a 10 GB hardrive. With the exception of MRAM, none of the spintronic devices such as spin based light emitting diodes (spin LEDs), resonant tunneling diodes (spin RTDs), field effect transistors (spin FETs), and spin based single electron devices based on quantum dot arrays can be fabricated without the ability to generate, maintain, and propagate long lived spins in a semiconductor.

All spintronic or more specifically semiconductor spintronic devices act according to the simple scheme: (1) information is stored (written) into spins as a particular spin orientation (up or down), (2) the spins, being attached to mobile electrons, carry the information along a wire, and (3) the information is read at a terminal . The basic idea behind semiconductor based spintronics is to add the characteristics of magnetic devices to existing devices such as light-emitting diodes and field effect transistors. This would lead to technologies such as memory and microprocessor functions integrated on the same chip, magnetic devices with gain and integrated sensors with on-chip signal processing and off-chip optical communications. A technology tree which summarizes the spin-based devices is shown is shown in Fig.2.

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Fig. 2 a technology tree for Spin based device

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3.2. Ferromagnetic semiconductors 3.2.1. Rare-earth chalcogenidesSince the 1960s rare-earth chalcogenides (e.g. EuO [16]) were found to possess both ferromagnetic and semiconducting properties. In these magnetic semiconductors, all magnetic atoms are periodically arranged in the crystal lattice as shown in Figure 2.1(a). Such ferromagnetic semiconductors show low transition temperatures usually not exceeding 70 K, i.e. far below room temperature. Moreover, the crystal structure of the rare-earth chalcogenides is quite different from that of technologically relevant semiconductors such as GaAs or Si, therefore these materials are rather difficult to integrate into semiconductor heterostructures for spintronic applications.

Fig.3.1 Schematic representation of (A) a magnetic semiconductor ,and (B) a diluted magnetic semiconductor.

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3.2.2. Diluted magnetic semiconductorsA landmark towards application was the discovery of diluted magnetic semiconductors (DMS). DMS materials are semiconductors in which a fraction of the host cations can be substitutionally replaced by transition metal or rare earth ions (as shown in Figure 2.1(B)). The partially filled 3d states or 4 f states contain unpaired electrons, which are responsible for localized magnetic moments. Transition metal doped II-VI compounds (such as Cd1xMnxSe, Hg1xMnxTe, etc.) are the most common DMSs studied in the early period. As the magnetic interaction in the II-VI DMS is dominated by anti ferromagnetic exchange between the transition metal moments, only paramagnetic, anti ferromagnetic, spin-glass behavior, or ferromagnetism with TC as low as 1.8 K have been observed . The difficulty in creating high p- and n-type doping levels, which is essential for obtaining high Curie temperatures, makes these systems less attractive for applications.

3.3 Ferromagnetic DMSThe ferromagnetic state was predicted to be favorable for V, Cr, Fe, Co, and Ni in ZnO while Mn-doped ZnO was anti ferromagnetic. In addition to the models mentioned above, Coey et al. used a spinsplit donor impurity band model to explain the observed systematic variation of magnetic moments across the TM-doped ZnO series, where V and Co showed much larger magnetic moment than other TM metals . For the light 3d elements, the 3d" states lie high in the 2p(O) and 4s(Zn) gap, overlapping the donor impurity band which is spin split. In the middle of the TM series, for instance Mn, there is no overlap with the 3d levels and exchange is weak, but towards the end of the series the 3d# states overlap the impurity band, which then has the opposite spin splitting for the same occupancy. High Curie12

temperatures are found whenever unoccupied 3d states overlap the impurity band, but not otherwise. The likely origin of the donor impurity band in ZnO films is lattice defects, such as oxygen vacancies. These predictions boosted intensive experimental activity on transition metal doped wide band gap semiconductors. Among them, transition metal doped ZnO is one of the most promising systems. ZnO is a direct band gap semiconductor with the bandgap of 3.3 eV at 300 K. ZnO normally has a hexagonal (wurtzite) crystal structure. The Zn atoms are tetrahedrally coordinated to four O atoms, where the Zn d electrons hybridize with the O p electrons. For example, Cd substitution leads to a reduction in the band gap to 3.0 eV. Substituting Mg on the Zn site in epitaxial films can increase the band gap to approximately 4.0 eV while still maintaining the wurtzite structure. ZnO is usually ntype due to electron doping via defects originating from Zn interstitials, O vacancies in the ZnO lattice, or impurities including hydrogen. High electron carrier density can also be realized via group III substitutional doping. Until recently, however, ZnO has proven difficult to dope p type. This is fairly common in wide band-gap semiconductors.

3.4. Zinc OxideZnO has been chosen as the key gas sensing material. Since it has been widely studied and is easily fabricated as high quality films, compatible with Si-based IC process. It is widely used material in various applications such as piezoelectric devices, varistors and SAW devices [2.1, 2.2]. The availability of ZnO is more in single crystal form.

3.4.1.

Properties of ZnO

Zinc oxide is an interesting II-VI compound semiconductor with a wide direct bandgap of 3.4 eV at room temperature [2.3]. It is a widely used material in various applications such as gas sensors, UV resistive13

coatings, piezoelectric devices, varistors, surface acoustic wave (SAW) devices and transparent conductive oxide electrodes [2.15, 2.16]. Recently, ZnO has also attracted attention for its possible application in short- wavelength light emitting diodes (LEDs) and laser diodes (LDs) because the optical properties of ZnO are similar to those of GaN [2.4, 2.5, 2.6]. Zinc oxide crystallizes in three forms: hexagonal wurtzite, cubic zincblende, and the rarely observed cubic rocksalt. The wurtzite structure is most stable and thus most common at ambient conditions. The zincblende form can be stabilized by growing ZnO on substrates with cubic lattice structure. In both cases, the zinc and oxide are tetrahedral. The rocksalt NaCl-type structure is only observed at relatively high pressures - ~10 GPa. The hexagonal structure has a point group 6 mm (HermannMauguin notation) or C6v (Schoenflies notation), and the space group is P63mc or C6v. The lattice constants are a = 3.25 and c = 5.2 ; their ratio c/a ~ 1.60 is close to the ideal value for hexagonal cell c/a = 1.633. As in most II-VI materials, the bonding in ZnO is largely ionic, which explains its strong piezoelectricity. Due to this ionicity, zinc and oxygen planes bear electric charge (positive and negative, respectively). Therefore, to maintain electrical neutrality, those planes reconstruct at atomic level in most relative materials, but not in ZnO its surfaces are atomically flat, stable and exhibit no reconstruction. This anomaly of ZnO is not fully explained yet. ZnO crystals are composed of alternate layers of zinc and oxygen atoms disposed in a wurtzite hexagonal close-packed structure with a longitudinal axis (c-axis) as shown in Figure 2.4. The oxygen atoms (ions) are arranged in close hexagonal packing, with zinc ions occupying half the tetrahedral interstitial positions with the same relative arrangement as the oxygen ions. In this crystal structure, both zinc and oxygen ions are coordinated with four ions of the opposite charge, and the binding is strong ionic type. Owing to the marked difference in size, these ions fill only about 44% of the volume in a ZnO14

crystal leaving open spaces of properties

some relatively large (0.095 nm). Typical ZnO are listed in

Table 1 [2.7].

Fig.3.2 Many properties of zinc oxide are dependent upon thewurtzite hexagonal, close-packed arrangement of the Zn and O atoms, their cohesiveness and void space.

Table 1 Properties of zinc oxide Crystal structure Molecular weight Lattice constant Density Hexagonal, wurtzite Zn:65.38, O:16 and ZnO:81.38 a = 3.246 , c = 5.207 5.67 g/cm3 or 4.21 x 109 ZnO molecules/mm3 Cohesive energy Melting point Heat of fusion Thermal conductivity Thermal expansion coefficient E coh = 1.89 eV Tm = 2250oK under pressure 4, 470 cal/mole 25 W/mK at 20 oC 4.3 x 10 -6/oK at 20oC 7.7 x 10 -6/ oK at 600oC Band gap at RT 3.37 eV

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Refractive index Electron and hole effective mass Debye temperature Lattice energy Dielectric constant Exciton binding energy Pyroelectric constant Piezoelectric coefficient

2.008

370 oK 964 kcal/mole , Eb = 30 meV 6.8 Amp./sec/cm2/ oK x 1010 D33= 12 pC/N

Pure zinc oxide, carefully prepared in a laboratory, is a good insulator; however, it can be increased in electrical conductivity many fold by special heat treatments and by the introduction of specific impurities into the crystal lattice. ZnO can even be made to exhibit metallic conductivity as for transparent electrodes similar to ITO. In general, 0.5-1% additions of trivalent cations (e.g. Al and Cr) decrease the resistivity of ZnO by about 10 orders of magnitude.

3.4.2

Chemical Properties

ZnO occurs as white powder commonly known as zinc white or as the mineral zincite. The mineral usually contains a certain amount of manganese and other elements and is of yellow to red color. Crystalline zinc oxide is thermo-chromic, changing from white to yellow when heated and in air reverting to white on cooling. This is caused by a very small loss of oxygen at high temperatures to form the nonstoichiometric Zn1+xO, where at 800C, x= 0.00007. Zinc oxide is an amphoteric oxide. It is nearly insoluble in water and alcohol, but it is soluble in (degraded by) most acids, such as hydrochloric acid:

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ZnO + 2 HCl ZnCl2 + H2O Bases also degrade the solid to give soluble zincates: ZnO + 2NaOH + H2O Na2 (Zn (OH)4) ZnO reacts slowly with fatty acids in oils to produce the corresponding carboxylates, such as oleate or stearate. ZnO forms cement-like products when mixed with a strong aqueous solution of zinc chloride and these are best described as zinc hydroxy chlorides. This cement was used in dentistry. ZnO also forms cement-like products when reacted with phosphoric acid, and this forms the basis of zinc phosphate cements used in dentistry. A major component of zinc phosphate cement produced by this reaction is hopeite, Zn3 (PO4)24H2O. ZnO decomposes into zinc vapor and oxygen only at around 1975C, reflecting its considerable stability. Heating with carbon converts the oxide into zinc vapor: ZnO + C Zn + CO Zinc oxide reacts violently with aluminum and magnesium powders, with chlorinated rubber and linseed oil on heating causing fire and explosion hazard. It reacts with hydrogen sulfide to give the sulfide: this reaction is used commercially in removing H2S using ZnO powder (e.g., as deodorant). ZnO + H2S ZnS + H2O When ointments containing ZnO and water are melted and exposed to ultraviolet light, hydrogen peroxide is produced.

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3.4.3

Electronic Properties

ZnO has a relatively large direct band gap of ~3.3 eV at room temperature; therefore, pure ZnO is colorless and transparent. Advantages associated with a large band gap include higher breakdown voltages, ability to sustain large electric fields, lower electronic noise, and high temperature and high-power operation. The band gap of ZnO can further be tuned from ~34 eV by its alloying with magnesium oxide or cadmium oxide. Most ZnO has n-type character, even in the absence of intentional doping. Native defects such as oxygen vacancies or zinc interstitials are often assumed to be the origin of this, but the subject remains controversial. An alternative explanation has been proposed, based on theoretical calculations, that unintentional substitutional hydrogen impurities are responsible. Controllable n-type doping is easily achieved by substituting Zn with group-III elements Al, Ga, In or by substituting oxygen with group-VII elements chlorine or iodine. Reliable p-type doping of ZnO remains difficult. This problem originates from low solubility of p-type dopants and their compensation by abundant n-type impurities, and it is pertinent not only to ZnO, but also to similar compounds GaN and ZnSe. Measurement of p-type in "intrinsically" n-type material is also not easy because in homogeneity results in spurious signals. Current absence of p-type ZnO does limit its electronic and optoelectronic applications which usually require junctions of n-type and p-type material. Known p-type dopants include group-I elements Li, Na, K; group-V elements N, P and As; as well as copper and silver. However, many of these form deep acceptors and do not produce significant p-type conduction at room temperature. Electron mobility of ZnO strongly varies with temperature and has a maximum of ~2000 cm2/ (Vs) at ~80 Kelvin.

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Chapter-4Experimental works

19

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4. DEPOSITION OF ZnO THIN FILM BY CWD TECHQUENIC High crystalline quality ZnO films are successfully deposited using a number of growth platforms, including molecular beam epitaxy (MBE), chemical vapor deposition (CVD), pulsed laser deposition (PLD), and reactive sputtering. Elemental sources (Zn and ozone or oxygen plasma), ceramic and targets (ZnO), and metal sol-Gel organic coating precursors technology (dimethylzinc have prepared the ZnO thin film samples grown on different substrates by using two methods one is CWD and SPIN COATING method. diethylzinc)

(spinning, dipping, or draining) are used with equal success. Her we

4.1 The description of CWD techquenicThe technology of sol-gel thin film has been around for over 20 years and is now well accepted as a technology for forming thin films and coatings. The process is simple, a solution containing the desired oxide or non-oxide precursor is prepared and is applied to a substrate by spinning, dipping, draining or spraying. The process is able to apply a coating to the inside and the outside of complex shapes simultaneously. The films are typical a few hundreds of nanometers thick, uniform over large areas and adherent. The equipment is inexpensive, especially in comparison to any deposition technique that involves vacuum. Coatings can be applied to metals, plastics, and ceramics. Typically, the coatings are applied at room temperature, though most need to be calcined and condensed by heating. Both amorphous and crystalline coatings can be obtained. There are many useful applications of sol-gel technology such as coating for optical, electronic, sensor, abrasion, barrier, protective, and catalyst applications. In some cases the quality of the coatings obtained by the sol-gel process is limited in comparison to oxidation, evaporation or sputtering techniques. The sol-gel process is the name given to any process involving a solution or sol that undergoes a sol-gel transition. A21

solution is a truly single-phase liquid, while a sol is a stable suspension of colloidal particles. At the transition, the solution or sol becomes a rigid, porous mass by destabilization, precipitation, or super saturation. Most of the coatings (spinning, dipping, or draining) present the sol-gel transitions from true one phase solutions to a rigid two-phase system of solid and solvent-filled pores. The sol-gel transition in this case is not reversible. Films are normally formed from SOG sols using the spinning technique. Most of SOG sols need to be stored in a refrigerator and they must be at room temperature before applying it to the substrate. A substrate, usually a silicon wafer, must be cleaned before coating. The substrate is placed on a spinner and about one ml of SOG is dropped on the centre of the substrate. Then the substrate is immediately rotated with a speed of a few thousand cycles per minute. In most cases, a film thickness between 50 and 500 nm will result. Controlling the thickness is a matter of controlling the solution viscosity. Typical solution viscosity is 3-10 mPa-s. Typical surface tension is 30-50x10-3 N/m. knowing the viscosity and oxide concentration of the solution, a film thickness can be achieved by controlling the spinning rate. When it comes to coatings, the SOG is said to go through a sol-gel transition, once the coating is on the substrate. What takes place on the molecular level is not well understood, but what is observed is that the solution film of perhaps 100 nm undergoes a sharp increase in viscosity. If the substrate has been handled properly, it is now covered uniformly by a tacky gel. In the systems described above, the sol-gel transition is reached when one-phase liquid becomes a two-phase alcogel, solid plus liquid. The alcogel is an oxide polymer that condenses in the presence of solvent. Alco gel is used to differentiate gels prepared with alkoxides from those prepared from ion-exchanged solutions or colloidal sols.

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Fig.4.1: Thin film formation by spinning techniqueThose gels are called hydro gels. The transition in alcogels is irreversible and occurs with no change in volume. The time of the transition depends on the chemistry of the solution, but the chemical composition of the two phases at the transition is not unique. Once through the sol-gel transition, the solvent phase is removed to create xerogels by ordinary evaporation or aero gels by hypercritical evacuation. At this point, the dried gel is a micro-porous oxide. After deposition, the film must be dried. During this step there are reductions by more than 50 % in weight and volume of the sol and gel. Yet the film remains adherent and continuous and maintains complete surface coverage. It has been shown repeatedly that all shrinkage is taken up in the dimension perpendicular to surface and not in the plane of the substrate. This holds as long as the thickness is about one micron or less. Drying is complete when there is no further weight loss. For the purpose of out-gassing, the drying temperature should be approximately 250oC.

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Fig.4.2 Spin coating machine The dipping process is able to apply a coating to the inside, outside and the side wall of the substrates simultaneously. A chemical reaction takes place when the substrate is dipped into the solution (ZnO) and is moved from the bottom to upwards in side constant temperature zone of a furnace having known temperature profile. To get the crystallites of the desired compounds the substrate is constantly moved at very slow speed drive motor during its preparation. In this method the solution containing the reactants are sticked on the surface of the substrate. The rest products are generally volatile and can be removed through an exhaust system. It is annealed by constant temperature zone when it is passed through the furnace

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very slowly. A schematic of the Chemically Wet and Dry set-up is in figure 4.3.

Figure 4.3 Schematic diagram of Chemically Wet and Dry (CWD) set up. Although the technique is very simple in approach it has several sensitive parameters to be controlled carefully for obtaining a good quality oxide film. One has to optimize several other parameters such as pull rates of substrate upward, temperature profile concentration of the solution, the volatile component of the solution, low viscous of solution, distance between the solution and the highest temperature zone of the vertical furnace and number of dips. The development of a low cost equipment CWD (Chemically Wet and Dry) set up for preparation of oxide semiconductor films is shown in figure 4.4.25

Figure 4.4 Low cost equipment Chemically Wet and Dry set up

4.2 Details components of the inventionThe basic constructional components used in the Chemically Wet and Dry (CWD) systems are as followsI. II. III. IV. V. VI. Movable stand. Controlled Drive motor. Variation temperature controller with cut off relay. Thermocouple. Vertical Furnace with a special temperature profile. Sample holder.

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Figure 4.5 Shows the graph of furnace temperature vs distance for CWD setup

4.3 Preparation of ZnO solution for thin filmFor preparation of ZnO thin film, we require the chemical solution by Sol Gel method [3.1, 3.2, 3.3, 3.4]. Mainly it is used for thin films. Major requirements are Zinc Acetate Dihydrate (Extra pure, M- 219.49 g/mol), Ethylene glycol (M- 62.07), Glycerol (98% purified, M- 92.10 g/mol), 2- propanol (M- 60.10g/mol), TEA (Tri Ethyl Amine, M- 101.19) and Acetone (M- 58.08). First clean all the equipments with the help of Acetone ((CH3)2CO), then taking 0.02 mole (4.3898 gm) of Zinc Acetate Dihydrate ((CH3COO)2 Zn H2O) in a beaker [3.4]. Add 10 ml Ethylene Glycol (C2H6O2) and 5-7 drops of Glycerol (C3H8O3) into the beaker and put it on at temperature of 1400C 1500C stir for 10 minute. After that cool it down to room temperature. Then add 15 ml of 2-proponol (CH3CHOHCH3) into it and start stirring at room temperature. Then slowly add 4 ml of TEA ((C2H5)3N), so that no turbidity forms and go on stir for 10 minutes. Finally ZnO solution is prepared which is used for dip coated in this research work. Device fabrication presumes the availability of an appropriately doped semiconductor. Before the device processing begins, the27

starting material has to be characterized in terms of its basic electrical parameters. The parameters of main interest are the conductivity type (n or p) and the resistivity, mobility, carrier concentration, and excess carrier lifetime [3.5].

4.4 Conductivity typeA simple method, which is widely used to determine the conductivity type of a semiconductor specimen, is the hot probe method which is shown in figure 4.5. Two fine metal probes, preferably made of stainless steel, are placed on the semiconductor sample and a digital multimeter is connected between them. One of the probes is kept at room temperature and the other is heated to about 800C. It is convenient to use a miniature soldering iron tip as the hot probe. The hot probe heats the semiconductor immediately beneath it so that the kinetic energy of free carriers in this region is increased. Therefore, the carriers diffuse out of the hot region at a faster rate than they diffuse into this region from the adjacent low-temperature regions [3.5].

Figure 4.6 shows hot probe method to determine the conductivity type If the semiconductor is n-type, electrons will move away from the hot probe leaving a positive charge region of donors, and the hot probe becomes positive with respect to the cold end. The current then will28

flow the hot probe to the cold probe. In a p-type semiconductor, the direction of the current flow is reversed. Thus the polarity of the hot probe indicates whether the semiconductor is n- or p-type.

4.5 ResistivityThe most commonly used technique in the semiconductor industry for measuring resistivity is the four-point probe method [4.2]. This method is non-destructive and can be used to measure the resistivity of the ingots, as well as wafers. The arrangement is shown in figure 4.6. Four collinear metal probes with sharpened tips are placed on the semiconductor. A constant current I is passed through the two outer probes and the potential difference V developed across the inner two probes is measured using a high-input impedance voltmeter. For collinear probes with separations placed on a semi-infinite medium, the resistivity is given by

Figure 4.7 Resistivity measurements with Four Probe Setup

4.6 Hall Effect measurements

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The importance of the Hall Effect is underscored by the need to determine accurately carrier density, electrical resistivity, and the mobility of carriers in semiconductors [3.5]. The Hall Effect provides a relatively simple method for doing this. Because of its simplicity, low cost, and fast turnaround time, it is an indispensable characterization technique in the semiconductor industry and in research laboratories. In a recent industrial survey, it is listed as one of the most-commonly used characterization tools. Furthermore, two recent Nobel prizes (1985, 1998) are based upon the Hall Effect. Development of the technique has since led to a mature and practical tool, which today is used routinely for testing the electrical properties and quality of almost all of the semiconductor materials used by industry.

Figure 4.8 Setup for Hall Coefficients on Temperature For a rectangular bar of length l, width W, and thickness d placed in a magnetic flux B, the Hall constant or coefficient is given by

30

Where VH is the measured Hall Voltage, Ix is the current.

Chapter 5 Results and analysis

31

ResultsOnce the samples have been prepared, it is characterized using different techniques. Basically different properties like electrical, optical, structural properties, etc are to be characterized before the device processing starts.

5.1 High resolution optical microscope picturesIt was confirmed by studying effect of processing conditions with morphological surface view of prepared sample by high resolution optical microscope which is shown in Fig 5.3.1. Here the microscopic view was taken by optical microscope with a magnification of 40X. It was indicated that the prepared film is uniformly grown.

Fig- 5.1 Microscopic view of Ni doped ZnO thin film over glass substrate

Fig- 5.2 Microscopic view of Ni doped ZnO thin film over Aluminum substrate.32

Fig- 5.3 Microscopic view of Fe ZnO thin film over Aluminum substrate

Fig- 5.4 Microscopic view of Fe doped ZnO thin film on glass substate.

Fig- 5.5 Microscopic view of ZnO thin film 200x magnification.

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5.2 XRD CHARACTERIZATION: - The fact that X- ray have a wavelength of the order of angstroms, which is suitable for inter-atomic distances in solids, makes this technique an excellent instrument to investigate the crystalline structure of the materials. In our case, the XRay diffraction patters were obtained using a Siemens D-5000 X-ray diffractometer with CuK (=1.5406 ) radiation. All measurements were carried out at 35 kV and 30 mA in the range of 150 2 750. The scanning step and sampling time were 0.020 and one second, respectively.

5.2.1 XRD of bare ZnO nanocrystalsFigure 5.6 XRD patterns for bare ZnO synthesized at different aging times. All peaks correspond to ZnO wurtzite structure. ZnO was rapidly formed even right after 10 minutes of mixing without aging. The broadness of the XRD peaks reveals the nanocrystalline nature of the ZnO powders.

Figure 5.6 XRD patterns for bare ZnO

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5.2.2 XRD of ZnO with Ni dopedThe observed diffraction patterns of sharp peaks were indexed that prepared samples are wurtzite crystal structure. This indicates the crystallization of the prepared samples.

.

Fig 5.7 X ray Diffraction studies 5% Nidoped ZnO system. After partial substitution of Zn by Ni, the diffraction pattern of x = 0.05 shows the same peak, which indicates that the wurtzite structure is not disturbed by Ni substitution. The lattice parameters of Zn0.95

Ni

0.05

O

was a = 3.2513 & c =5.2266 , V = 55.2501 3 respectively the reported a & c values for ZnO was found to be 3.2535 & 5.2151 & V =55.2032 3. Due to the large size of the Ni than that of Zn, the lattice parameters Zn0.95Ni0.05O was slightly changed. Shifting of peaks & increase in volume of may substitute the Zn atom. Zn0.95

Ni

0.05

O was indicated that Ni atom

35

The electrical resistivity of ZnO is characterized with the help of Fourpoint probe setup [5.1]. Figure5.8 showing the current-voltage relationships of Bulk ZnO with temperature variations.

Figure 5.8 Current-Voltage relationship with temperature variations It can be seen that the voltage increases smoothly with respect to the current for ZnO. The resistivity decreases as the temperature increases for bulk ZnO and hence the conductivity increases which shows the semiconductor property with negative temperature coefficients which is found to be same [5.2, 5.3, 5.4] and the nature of the graph is also same. The conductivity change with the reciprocal of temperature is shown in figure 5.9 (Appendix B). The prepared material was found to be ptype semiconductor by using hot probe experiment [5.1].

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Figure 5.9 shows the conductivity reciprocal of temperature graph.

GRAPHS FOR THE RESULTS

V g h o th B A m iu fo -I rap f e are lu in m li20 0

Current in Ampere

15 0

10 0

5 0

0

-0.10

-0.08

-0.06

-0.04

-0 .02

0.00

0.02

0.04

0.06

0.08

V ltag in V lt o e o

Fig.5.10:- for bare Aluminum foil current increases linearly with the increase of voltage.

37

L V-I characterstics of Cu200

150

Current in ampere

100

50

0

-0.095

-0.090

-0.085

-0.080

-0.075

-0.070

Voltage in volts

Fig.5.11:- for Copper current increases linearly with the increase of voltage

F20

VI characterstics of Si

Current in ampere

15

10

5

0

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

Voltage in volts

Fig.5.12:- for silicon current increases linearly with the increase of voltage.

38

B20 0

V c a c rs so A n c a d -I h ra e tic f l(Z O o te )

Current in Ampere

10 5

10 0

5 0

0

-0.0 6

-0 .05

-0.0 4

-0.03

-0.0 2

-0.01

0 0 .0

0 1 .0

0 2 .0

V lta einv lts o g o

Fig.5.13:-For aluminium coated with ZnO,the current remains zero for lower value of voltage and suddenly increase for higher value of voltage.

Fig.5.14:- For glass substrate coated with Ni doped ZnO, the current remains zero for lower value of voltage and suddenly increase for higher value of voltage.

39

Fig.5.15:- For aluminium coated with Ni doped ZnO, the current remains zero for very lower value of voltage and suddenly increase for higher value of voltage.

Fig.5.16:- For aluminium coated with Fe doped ZnO, the current remains zero for very lower value of voltage and suddenly linearly increase for higher value of voltage

Fig.5.17: - for glass substrate coated with Fe doped ZnO, the current remains zero for lower value of voltage and suddenly increase for higher value of voltage.

40

From the above VI graphs it is observed that the when the

substrate is conducting the performance of ZnO thin film is increasing.Again transition metals Fe and Ni when doped with ZnO the film

on Aluminium has the better response in VI characteristic compare to glass substrate.

Current in ampere

Vc aa esrc o C( n ) I hr c r t i s f uZ O14 . 12 . 10 . 08 . 06 . 04 . 02 . 00 . -. 02 -.8 00 -.6 00 -.4 00 -.2 00 00 .0 00 .2

J

00 .4

Vl a en o o g i vl t t

Fig.5.18: - For cu coated with ZnO,the current increses with the increase of voltage.H v-I characterstics of C u(ZnO +Fe(5% ))coated0.08

Current in ampere

0.06

0.04

0.02

0.00

0.14

0.15

0.16

0.17

0.18

0.19

Voltagein volts

Fig.5.19- For Cu coated with ZnO doped Fe the current increase withthe increase of voltage.

HALL EFFECT:It has been clear from the graph that the Hall voltage decreases with increase in temperature without corrected Hall voltage (Appendix41

C). The probe current was found to be 4.02 mA, residual magnetic field is 125 Gauss and magnetic field is 3 KG with the current applied to was 0.02 A. The graph is not smooth as the graph shown in figure 5.4 below with corrected Hall voltage.

Figure 20 (A, B) variation of Hall coefficient with temperature

Figure5.4(A, B) the graph showing variation of Hall coefficient with temperature for sample of thickness 0.5 mm. It has been clear from the graph that with increase in temperature the Hall coefficient decreases and which is a smooth curve as it includes the corrected Hall voltage (Appendix D).42

There are practical aspects which must be considered while carrying out Hall and resistivity measurements. Primary concerns are ohmic contact quality and size, sample uniformity and accurate thickness determination.

voltage8 7 6

Hall Effect on Al(ZnO coated)

Hall Voltage,Vh(mV)

5 4 3 2 1 0 0.0 0.5 1.0 1.5 2.0 2.5

Hall Current,Ix(mV)

Fig.5.20- The hall voltage increases linearly with the increase of hall current aluminium coated with ZnO .

43

B-90

Hall Effect of Aluminium (ZnO+Ni)

-100

-110

Hall voltage

-120

-130

-140

-150 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Hall current

Fig.5.21- The hall voltage increases linearly with the increase of hall current for Aluminium coated with ZnO (Ni doped).

Inductance (L), Capacitance(C), Resistance(R) measurement

Copper (Coated with ZnO):Frequency vs. Inductance

44

2 0 0 -0 2

Fe u n y In u t n e r q e c ~ d ca c C c a dw hZ O u o te it n

In u ta c dc ne

Inductance

-0 4 -0 6 -0 8 -0 10 -2 10 -4 10 -6 10 -8 10 0 50 00 100 00 100 50 200 00

Fe u n y r qec

Fig.5.22: Inductance increases exponentially in a sudden at a lower temperature and after attaining a peak value becomes constant.

Frequency vs. capacitance:Fe u n y C p c n e r q e c ~ a a ita c ( uc a dw hZ O C o te it n ) Cp c ne a a ita c

1 2 -0 0 .5 E 1 1 0 -0 0 .5 E 1

Capacitance

1 8 -0 0 .4 E 1 1 6 -0 0 .4 E 1 1 4 -0 0 .4 E 1 1 2 -0 0 .4 E 1 1 0 -0 0 .4 E 1 1 8 -0 0 .3 E 1 1 6 -0 0 .3 E 1 1 4 -0 0 .3 E 1 0 50 00 100 00 100 50 200 00

Fe u n y r qec

Fig.5.23:Capacitance smoothly decreases exponentially.

Frequency vs. resistance:

45

F q e cy R s ta c re u n ~ e is n e (C c a dw Z O u o te ith n )1000 2000

R s ta c e is n e

1000 0000

Resistance

8000 000

6000 000

4000 000

2000 000 0 50 00 100 00 100 50 200 00

F qec re u n y

Fig.5.24: resistance exponentially decreases.

Aluminium (coated with ZnO):Frequency vs. Inductance:

Freq.~ Inductance (Aluminium(coated with ZnO))0

B

-50

Inductance in H

-100

-150

-200

-250 0 5000 10000 15000 20000

Frequency in Hz

Fig.5.25: Inductance increases exponentially in a sudden at a lower temperature and after attaining a peak value becomes constant.

Frequency vs. capacitance:46

c p ca c a ai ne t1 7- 1 . E 0 1 0

Capacitance(F)

1 7- 1 . E 0 1 0 1 6- 1 . E 0 1 0 1 6- 1 . E 0 1 0 1 5- 1 . E 0 1 0 1 5- 1 . E 0 1 0 1 4- 1 . E 0 1 0 1 4- 1 . E 0 1 0 1 4- 1 . E 0 1 0 0 50 00 100 00 1 00 50 200 00

F q e c( z r u nyH) e

Fig.5.26: - the capacitance shows a higher value at lower frequency anddecreases exponentially with the increase of freq.

Frequency vs. resistance:Resistance in Ohm

1 0 +0 . E0 8 0

F qv.r s t ne r . s ei a c e s FrA mi mot d i h n ) o l i u ( a w ZO u n c e t

B

0 0 +0 . E0 0 0

- . 0 +0 1 E0 8 0

- . 0 +0 2 E0 8 0

- . 0 +0 3 E0 8 0

- . 0 +0 4 E0 8 0 0 50 00 1 00 00 1 00 50 2 00 00

F qec i H r unyn z e

Fig.5.27:- the resistance remains at zero for all frequencies.

47

Silver (coated with ZnO)Frequency vs. Inductance:Inductance18000000 16000000 14000000 12000000

Frequency vs. Inductance for silver(coated with ZnO)

Inductance(H)

10000000 8000000 6000000 4000000 2000000 0 -2000000 0 5000 10000 15000 20000

Frequency(Hz)

Fig.5.28:- The inductance remains zero for all frequencies .

Frequency vs. capacitance:Capacitance35000000 30000000 25000000

Frequency vs. Capacitance For Ag(coated with ZnO)

Capacitance(F)

20000000 15000000 10000000 5000000 0 0 5000 10000 15000 20000

Frequency(Hz)

Fig.5.29s:- The capacitance remains zero for all frequencies

48

Frequency vs. resistance:Resistance45000000 40000000 35000000 30000000 25000000 20000000 15000000 10000000 5000000 0 5000 10000 15000 20000

Frequency vs. resistance For silvercoated with ZnO)

Resistance(Ohm)

Frequency(Hz)

Fig.5.30s:- the resistance is high at lower frq. And exponentially decreaseswith the increase of freq.

49

Chapter -6Conclusion and scope for future work

50

6.1 CONCLUSIONThe present work was focused on the synthesis of highly monodisperse bare and TM-doped ZnO nanocrystals (where TM = Ni and Fe) in ethanol solutions at room-temperature and their structural, optical and magnetic characterization. In this thesis, detailed investigations of the structure and the magnetic properties of transition metal (TM) implanted semiconductors, (i) as-purchased ZnO single crystals (ii) pre annealed ZnO, have been presented. Various experimental techniques, such as XRD, fore probe, halls effect and hot probe have been employed to study the above systems. In an overview, the achievements in this thesis can be summarized as follows: (1) clarify the origin of the magnetic properties in TM implanted ZnO (2) figure out the difficulty to detect nanocrystals embedded inside semiconductors, and (3) find an approach to get the other properties of the TM doped ZnO on different substrates.

6.2

SCOPE FOR FUTURE WORKThe TM can be changed with different cosentration for the

preparation of ZnO thin films. Thin film deposition on ZnO can be done with different substrates using different caoting techniques. The different characteristics like photo electric effects, feromagnetic effects, resistivity measurement, conductivity, hall coefficients measurements, surface morphology, and X-ray diffraction can also be studied. Then compare the prepared simulated device results of the with the reference data whether the device may or may not be usefull for the spintronic devices.

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PUBLICATIONS

52

REFERENCES[1]. Yue-Hui Hu, Yi-Chuan Chen, Hai-Jun Xu, Hao Gao Texture ZnO Thin-Films and their applications Journal of scientific research, Vol.2 No.12, December 2010 [2] Keunkyu Song1, Junghun Noh2, Taehwan Jun1, Solution-Deposited ZnO Thin-Film Transistors Article published online: 23 AUG 2010 Advanced MaterialsVolume 22, Issue 38. [1.1] S. Capone et. al.: Solid State Gas Sensors: State Of The Art And Future Activities, Journal of Optoelectronics and Advanced Materials, Vol. 5, 2003, pp 1335. [1.2] C. C. Liu et. al. : Chemical Microsensors, The Electrochemical Society Interface, summer 2004. [1.3] Andreas Hierlemann et. al. Microfabrication Techniques for Chemical/Biosensors, Proceedings of the IEEE, Vol. 91, No. 6, June 2003. [1.2] M. H. Huang et. al. : Room-temperature ultraviolet nanowire nanolasers, Science, Vol. 292, 2001, pp 1897-1899. [2.1] R. P. Ried et. al.: Piezoelectric microphone with on-chip CMOS circuits, Journal of Microelectromechanical Systems, Vol. 2, (1993, pp 111-120. [2.2] Y. Ito at. al.: A 100-Mhz ultrasonic transducer array using ZnO thin films, IEEE Transaction on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 42, 1995, pp 316-323. [2.3] M. H. Huang et. al.: Room-temperature ultraviolet nanowire nanolasers, Science, Vol. 292, 2001, pp 1897-1899. [2.4] M. Komatsu et. al.: GaN solubility limit in co-implanted ZnO measured by secondary ion mass spectrometry, Applied Surface Science, Vol. 189, 2002, pp 349-352. [2.5] S. Tuzemen et. al.: Production and properties of p-n junctions in reactively sputtered ZnO, Physica B, Vol. 308-310, 2001, pp 1197-1200. [2.6] Y. R. Ryu and W. J. KimL: Fabrication of homostructural ZnO p-n junctions, Journal of Crystal growth, Vol. 219, 2000, pp 419-42253

[2.7] H. E. Brown: Zinc oxide; Properties and applications, International Lead Zinc Research Organization, Inc., New York, 1976 [3.1] B. Gupta, A. Jain, of R. M. Mehra: Derived Development Al Doped and

Characterization

Sol-gel

ZnO/p-Si

Photodiode, Journal of material science and technology, Vol. 26, No 3, 2010, pp 223-227. [3.2] M. S. Tyagi: Introduction to semiconductor materials and devices, John Wiley & Sons, 2000. [4.1] M. Jin et. al.: Optical and electronic properties of transparent conducting ZnO and ZnO: Al films prepared by evaporating method, Thin solid films, Vol. 357, 1999, pp 98-101. [4.2] S. Suwanboon, R. Tanattha, R. Tanakorn: Fabrication and properties of nanocrystalline ZnO thin film prepared by sol-gel method, Songklanakarin journal of science and technology, Vol. 30, No 1, Jan-Feb 2008, pp 65-69

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APPENDIX-ADatas for current-voltage relationship with temperature variations Current I (A) Temperat ure at 1000C 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.25 Temperat ure at 1200C 0.01 0.02 0.04 0.05 0.07 0.08 0.09 0.11 0.12 0.14 0.15 0.16 0.18 0.19 0.2 Temperat ure at 1400C 0.01 0.02 0.04 0.05 0.06 0.08 0.09 0.11 0.12 0.14 0.15 0.16 Temperat ure at 1600C 0.01 0.03 0.05 0.06 0.08 0.1 0.11 Voltage V (V)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

55

APPENDIX-B

Datas for the conductivity vs reciprocal of temperature

Reciprocal of temperature (1/T) in 0C 0.01 0.00833 0.00714 0.00625 0.00555 0.005

Conductivity (ln )

-10.13 -9.77 -9.08 -8.36 -7.37 -6.67

56

APPENDIX-CDatas from LCR meter for ZnO-NiFrequency (Hz) 1.0000E+03 1.1514E+03 1.3258E+03 1.5265E+03 1.7577E+03 2.0238E+03 2.3303E+03 2.6831E+03 3.0894E+03 3.5572E+03 4.0958E+03 4.7160E+03 5.4301E+03 6.2524E+03 7.1991E+03 8.2892E+03 9.5443E+03 1.0990E+04 1.2654E+04 1.4570E+04 1.6776E+04 1.9316E+04 2.2241E+04 2.5609E+04 2.9486E+04 3.3951E+04 3.9092E+04 4.5011E+04 5.1827E+04 5.9674E+04 6.8710E+04 7.9115E+04 9.1094E+04 1.0489E+05 1.2077E+05 1.3906E+05 1.6011E+05 1.8436E+05 2.1227E+05 2.4442E+05 2.8143E+05 3.2404E+05 3.7311E+05 4.2960E+05 4.9465E+05 5.6955E+05 Parallel R (Ohm) -5.0944E+01 -5.1425E+01 -4.9583E+01 -4.9963E+01 -4.9734E+01 -5.1057E+01 -5.1368E+01 -5.2927E+01 -5.3558E+01 -5.5793E+01 -5.6880E+01 -5.8268E+01 -6.0377E+01 -6.3304E+01 -6.6447E+01 -6.9667E+01 -7.0631E+01 -8.1996E+01 -8.4096E+01 -8.7741E+01 -8.5930E+01 -9.3672E+01 -9.1104E+01 -9.8875E+01 -1.0079E+02 -9.7822E+01 -1.0658E+02 -1.0229E+02 -1.1609E+02 -1.1545E+02 -1.1590E+02 -1.1477E+02 -1.4968E+02 -1.3130E+02 -1.3625E+02 -9.0815E+01 -8.4158E+01 -2.0266E+02 -9.5161E+01 -1.2488E+02 -2.1736E+02 -9.9976E+01 -9.2987E+01 -6.7676E+01 -1.2881E+02 1.4138E+04 Parallel C (F) -2.8807E-09 2.6476E-08 1.7240E-07 1.5972E-07 1.9311E-07 1.8056E-07 2.1575E-07 2.1154E-07 1.9457E-07 1.7276E-07 1.6919E-07 1.6297E-07 1.3793E-07 1.3682E-07 1.0494E-07 8.9789E-08 7.5805E-08 7.3515E-08 6.3189E-08 4.7667E-08 4.5014E-08 3.3264E-08 2.7193E-08 2.1093E-08 1.5421E-08 9.4636E-09 9.6515E-09 1.0298E-08 1.0040E-08 3.7434E-09 5.1892E-09 4.4431E-09 1.8712E-09 4.9625E-09 -9.4515E-11 -1.4055E-09 1.5722E-09 7.1938E-09 8.8494E-10 1.2892E-09 4.5238E-09 1.4900E-09 -1.4824E-09 -6.2562E-10 -2.6706E-09 -1.9741E-09 57 Parallel L (H) 8.7932E+00 -7.2163E-01 -8.3594E-02 -6.8059E-02 -4.2459E-02 -3.4251E-02 -2.1621E-02 -1.6633E-02 -1.3640E-02 -1.1587E-02 -8.9245E-03 -6.9887E-03 -6.2282E-03 -4.7360E-03 -4.6574E-03 -4.1058E-03 -3.6682E-03 -2.8530E-03 -2.5036E-03 -2.5034E-03 -1.9995E-03 -2.0409E-03 -1.8831E-03 -1.8312E-03 -1.8893E-03 -2.3221E-03 -1.7174E-03 -1.2141E-03 -9.3930E-04 -1.9002E-03 -1.0340E-03 -9.1083E-04 -1.6313E-03 -4.6397E-04 1.8375E-02, 9.3201E-04 -6.2846E-04 -1.0360E-04 -6.3524E-04 -3.2891E-04 -7.0698E-05 -1.6190E-04 1.2275E-04 2.1938E-04 3.8765E-05 3.9555E-05

6.5580E+05 7.5510E+05 8.6943E+05 1.0011E+06

8.7793E+01 -1.4834E+02 -5.8426E+01 7.0360E+02

-1.7085E-09 -1.2312E-09 2.5174E-10 1.9228E-09

3.4473E-05 3.6083E-05 -1.3311E-04 -1.3145E-05

VITA

Born on DATE MONTH YEAR (YOUR DATE OF BIRTH) , Odisha, YOUR NAME received his Bachelor degree in Electronics and Telecommunication Engineering from COLLEGE NAME, Bhubaneswar, Odisha in 200-. Then he did his Master degree in Electronics and Telecommuncation Engineering with specialization in ------------------------ in 2012 from BPUT University, Odisha.

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