PLDlecture2 (1).ppt

7/26/2019 PLDlecture2 (1).ppt

1/32

Pulsed Laser Deposition (PLD)

Anne Reilly

College of William and Mary

Department of Physics


2/32

Outline

1 !hin film deposition

" Pulsed Laser Deposition

a) Compared to other gro#th techni$ues

%) &'perimental etup

c) Adantages and Disadantages

* +asic !heory of PLD

, Opportunities


3/32

!hin -ilm Deposition

!ransfer atoms from a target to a apor (or plasma) to a su%strate


4/32

!hin -ilm Deposition

!ransfer atoms from a target to a apor (or plasma) to a su%strate

After an atom is on surface. it diffuses according to/ D0Doe'p(D23!)Dis the actiation energy for diffusion 4 "* e5

3! is energy of atomic species

Want sufficient diffusion for atoms to find %est sites

&ither use energetic atoms. or heat the su%strate


5/32

target

su%strate

&aporation

(Molecular %eam

epita'yM+&)

Ways to deposit thin films

target

su%strate

Chemical

apor

deposition

C5D

Ar6

su%strate

gas

puttering


6/32

Lo# energy deposition

(M+&)/ 471 e5

may get islanding unless

you pic3 right su%strate or

heat su%strate to high

temperatures

8igh energy deposition

(puttering 4 1 e5)

smoother films at lo#er

su%strate temperatures. %ut

may get intermi'ing


7/32

Lo# energy deposition

(M+&)/ 471 e5

may get islanding unless

you pic3 right su%strate or

heat su%strate to high

temperatures

8igh energy deposition

(puttering 4 1 e5)

smoother films at lo#er

su%strate temperatures. %ut

may get intermi'ing


8/32

CCD 2PM!

spectrometer

!arget

u%strates

or -araday

cup

laser %eam

Pulsed Laser Deposition


9/32

CCD 2PM!

spectrometer

!arget

u%strates

or -araday

cup

laser %eam

Pulsed Laser Deposition

!arget/ 9ust a%out anything: (metals. semiconductors;)

Laser/ !ypically e'cimer (


10/32


11/32

Adantages of PLD

-le'i%le. easy to implement

=ro#th in any enironment

&'act transfer of complicated materials (>+CO)

5aria%le gro#th rate

&pita'y at lo# temperature

Resonant interactions possi%le (ie. plasmons in metals.

a%sorption pea3s in dielectrics and semiconductors)

Atoms arrie in %unches. allo#ing for much more controlled

deposition

=reater control of gro#th (eg. %y arying laser parameters)


12/32

Disadantages of PLD

?


13/32

Processes in PLD

Laser pulse


14/32

Processes in PLD

e-e-

e-

e-e-

e-

e-

e-

e-

e-e-

e-

e-

e-

&lectronic e'citation


15/32

Processes in PLD

e-e-

e-

e-e-

e-

e-

e-

e-

e-e-

e-

e-

e-

&nergy rela'ation to lattice (41 ps)

lattice


16/32

Processes in PLD

8eat diffusion (oer microseconds)

lattice


17/32

Processes in PLD

Melting (tens of ns). &aporation. Plasma

-ormation (microseconds). Resolidification

lattice


18/32

Processes in PLD

lattice

f laser pulse is long (ns) or

repetition rate is high. laser maycontinue interactions


19/32

Processes in Pulsed Laser Deposition

1Absorption of laser pulse in materialBa%0(1R)oeL

(metals. a%sorption depths 4 17 nm.depends on )

"Relaxation of energy(4 1 ps) (electronphonon interaction)

*Heat transfer, Melting and Evaporation

#hen electrons and lattice at thermal e$uili%rium (long pulses)

use heat conduction e$uation/

(or heat diffusion model)abp QTK

t

TC +=

)(


20/32

Processes in Pulsed Laser Deposition

,Plasma creation

threshold intensity/

goerened %y aha e$uation/

Absorption of light by plasma, ioniation

(inerse +remsstrahlung)

!nteraction of target and ablated species "ith plasma

E #ooling bet"een pulses

(Resolidification %et#een pulses)

pulsethreshold

t

cmWsxI

""21,17, =

+

=kTmm

mm

Q

QQ

n

nn ion

ie

ie

n

ie

n

ie e'p


21/32

Incredibly Non-Equilibrium!!!

At peak of laser pulse, temperatures on target can

reach >1" #> $ e%!&

Electric 'ields > 1%(cm, also high magnetic fields

)lasma *emperatures +- "

Ablated pecies ith energies 1 .1 e%


22/32

PLD "ith $ltrafast Pulses %& ' picosecond(see tuart et al. Phys Re +. +1E,F (1FF)

A ne# research area:

f the pulse #idth G electron latticerela'ation time. heat diffusion. melting significantly

reduced: Means cleaner holes and cleaner a%lation

Direct conersion of solid to apor. less plasma formation

Reactie chemistry/ energetic ions. ioniHed nitrogen. high charge states

Leads to less target damage (cleaner holes). and smoother films (less particulates)


23/32

PLD "ith $ltrafast Pulses %& ' picosecond(see tuart et al. Phys Re +. +1E,F (1FF)

A ne# research area:

f the pulse #idth G electron latticerela'ation time. heat diffusion. melting significantly

reduced: Means cleaner holes and cleaner a%lation

Direct conersion of solid to apor. less plasma formation

Reactie chemistry/ energetic ions. ioniHed nitrogen. high charge states

Leads to less target damage (cleaner holes). and smoother films (less particulates)

I 7 psConentional melting. %oiling and fracture

!hreshold fluence for a%lation scales as 12"

G 17 ps&lectrons photoioniHed. collisionaland multiphoton ioniHation

Plasma formation #ith no melting

Deiation from 12" scaling


24/32

!

AR=&!

-ALM

(depositedonsilicon)

/ ns E0I2E3 4ersus 1 ps *5NA'-'E6

Co%alt 4"7 m92pulse. "7 ns. *7J nm.

" 8H. 1 ' 17!orr

teel. 4"7 92pulse. 1J M8H. *1 micron1 ' 17"!orr. 7 8H pulsed. rastered %eam

6ess melting!

'e

particulates!for Nb7 8 1 per cm-/

&Ms %y + Ro%ertson. ! Wang. !9@A-


25/32

Opportunities


26/32

2agnetic 2oment of fcc 'e#111& 9ltrathin 'ilms

by 9ltrafast :eposition on u#111&

5; hen et al;, )hys; 3e4; 6ett;,


27/32

MICE

?Direct #riting of electronic components in air:

?Rapid process refinement

?@o mas3s. preforms. or long cycle times

?!rue *D structure fa%rication possi%le

?ingle laser does surface pretreatment. spatially selectie material deposition.

surface annealing .component trimming. a%latie micromachining. dicing andiadrilling


28/32

Isotope Enrichment in 6aser-Ablation )lumes and ommensurately

:eposited *hin 'ilms

); ); )ronko, et al; )hys 3e4; 6ett;,


29/32

!ransient tates of Matter during hort Pulse Laser A%lation

"; okoloski-*inten et al;,)hys; 3e4; 6ett;,


30/32

http/22###ornlgo24odg2Knanotu%es

@e# Materials and @anoparticles

D+ =eoheganOR@L

Car%on2car%on collisons

%uc3y%alls

-ast car%on ions

diamond films

tudy of plasma plume and deposition of car%on materials


31/32


32/32

References

Pulsed Laser 5aporiHation and Deposition. Wilmott and8u%er. Reie#s of Modern Physics. 5ol E". *1 ("777)

Pulsed Laser Deposition of !hin -ilms. Chrisey and

8u%ler (Wiley. @e# >or3. 1FF,)

Laser A%lation and Desorption. Miller and 8aglund

(Academic Press. an Diego. 1FFJ)

Documents

PLDlecture2 (1).ppt