Talent Management at California Casualty Management Co. PCIAA

UV-LEDUV-LEDbased upon AlGaNp

by Marcus Pohlby Marcus Pohl

Table of ContentTable of Content• History• MotivationsMotivations• LED

– functionality– assemblyy

• AlGaNAlG N UV LED• AlGaN UV-LED

• ApplicationsSlide: 2

pp11/06/2012 Marcus Pohl

History of the LEDHistory of the LED1907: Henry Joseph Round observed light emission

from inorganic matter if voltage is appliedi 1957 t i ti i d tsince1957: restriction on semiconductor

1961 R b t Bi d d G Pitt t t d1961: Robert Biard and Gary Pittman patented the first infrared LED based on GaAs

1962: Nick Holonyak Jr. (General Electrics) invent first practical LEDpractical LED

1972: M George Craford invented yellow LED

Slide: 3

1972: M. George Craford invented yellow LED

11/06/2012 Marcus Pohl

History of the LEDHistory of the LED1992: Isamu Akasaki invented first UV-LED

Light output per LED as a function of production year

Slide: 411/06/2012 Marcus Pohl

MotivationsMotivations• replacement of low-pressure mercury

lamps p• replacement of mercury discharge for the

excitation of lamp phosphorsexcitation of lamp phosphors


Basics of LEDBasics of LEDFunctionality:


Basics of LEDBasics of LEDAssembly of a LED:


UV LEDUV-LEDMaterials for Ultraviolet-LED’s

– Diamond (235 nm)– Aluminium gallium nitride (AlGaN) (220 nm)– Boron nitride (BN) (215 nm)( ) ( )– Aluminium nitride (AlN) (210 nm)– Aluminium gallium indium nitride (AlGaInN) (210 nm)g ( ) ( )


AlGaNAlGaNLuminescent properties:properties:


AlGaNAlGaNInfluence of the Al-contenton the band gap:


AlGaNAlGaNElectrical properties:• increase of resistivity with increasing Al-contenty g• increase of conductivity possible via doping

– p-type: Mgp type: Mg– n-type: Si


AlGaNAlGaNInfluence of Si-doping:• critical dopant concentration for Si at 1*1018 cm-3 in

case of Al-content above 0,4• doping with Si causes a shift of

the PL to longer and increasein intensity


AlGaNAlGaNDifficulty of p-doping:• emission wavelength higher as

b d i i d t b dband gap emission due to band-to-impurity transitions for e.g. Mgin case of low hole density• in case of low hole density electron flow into the p-layeriincreases

-> decrease of light-output


AlGaN UV LEDAlGaN UV-LEDAssembly of an AlGaN UV-LED


AlGaN UV LEDAlGaN UV-LEDBand structure ofAlGaN in a MQW-LED:


ApplicationsApplications• replacement of low-pressure mercury

lamps p• replacement of mercury discharge for the

excitation of lamp phosphorsexcitation of lamp phosphors• water/air purification• disinfection of surfaces

medical treatment (dermato• medical treatment (dermato-logic, light therapy)

Slide: 16

g g py)


ConclusionsConclusions• AlGaN demanding material

– relatively simple n-type doping (Si)y p yp p g ( )– difficult p-type doping

advantage: band gap engineering possible– advantage: band gap engineering possible

• promising future material if problems can• promising future material if problems can be overcome


ReferencesReferencesIsamu Akasaki et al “Photoluminescence of Mg doped p type GaN and• Isamu Akasaki et al., Photoluminescence of Mg-doped p-type GaN and electroluminescence of GaN p-n junction LED”, Journal of Luminescence 48 & 49 (1991), pp. 666-670

• H.X. Jiang et al., “AlGaN and InAlGaN alloys – epitaxial growth, optical and electrical ti d li ti ” O t l t i R i 10 (2002) 271 286properties, and applications”, Opto-eletronics Review 10 (2002), pp. 271–286

• Hideki Hirayama, “Development of 230–270 nm AlGaN-Based Deep-UV LEDs”, Electronics and Communications in Japan 93 (2010), pp. 748–756

• Daniel Steigerwald et al., “III-V Nitride Semiconductors for High-Performance Blue and Green Light-emitting Devices”, Journal of the Minerals, Metals and Materials Society 49 (1997), pp.18-23

• J. Li et al., “Optical and electrical properties of Al-rich AlGaN alloys”, Applied Physics Letters 79 (2001), pp. 3245-3247( ) pp

• P. Kung et al., “III-Nitride wide bandgap semiconductors: a survey of the current status and future trends of the material and device technology”, Opto-eletronics Review 8 (2000), pp. 201-239

• http://www aquionics com/main/aquionics-news/world%E2%80%99s-first-uv-led-http://www.aquionics.com/main/aquionics news/world%E2%80%99s first uv leddisinfection-system/

• http://quantum-algorithms.com/waveeng.html• http://en.wikipedia.org/wiki/LED

htt // i d / h b t/Li ht E itti Di d d t / h 04/ h 04 ht

Slide: 18

• http://www.ecse.rpi.edu/~schubert/Light-Emitting-Diodes-dot-org/chap04/chap04.htm


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