BLACK SILICON FOR NEXT-GENERATION INFRARED · PDF fileBLACK SILICON FOR NEXT-GENERATION INFRARED SENSORS ... Black Silicon for Next-Generation Infrared Sensors ... T•r Nd Pm Srn

U.S. Army Research, Development and Engineering Command

August 2012

BLACK SILICON FOR NEXT-GENERATION

INFRARED SENSORS

Dr. Jeffrey Warrender

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1. REPORT DATE AUG 2012 2. REPORT TYPE

3. DATES COVERED 00-00-2012 to 00-00-2012

4. TITLE AND SUBTITLE Black Silicon for Next-Generation Infrared Sensors

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6. AUTHOR(S) 5d. PROJECT NUMBER

5e. TASK NUMBER

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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Research, Development and Engineering Command,Picatinny Arsenal,NJ,07806-5000

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12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited

13. SUPPLEMENTARY NOTES Presented at the 2nd Multifunctional Materials for Defense Workshop in conjunction with the 2012 AnnualGrantees’/Contractors’ Meeting for AFOSR Program on Mechanics of Multifunctional Materials &Microsystems Held 30 July - 3 August 2012 in Arlington, VA. Sponsored by AFRL, AFOSR, ARO, NRL,ONR, and ARL.

14. ABSTRACT

15. SUBJECT TERMS

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as

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Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18

Collaborators

ARDEC Jay Mathews, V. Swaminathan

RPI Peter Persans, Dave Hutchinson, Alex Katauskas

Harvard Mike Aziz, Austin Akey, Dan Recht, Aurore Said, Eric Mazur, Meng-Ju Sher, Yuting Lin

MIT Tonio Buonassisi, Mark Winkler, Joe Sullivan, Christie Simmons, Jeff Grossman, Elif Ertekin, Silvija Gradecak, Matt Smith

Australian National University

James Williams, Supakit Charnvanichborikarn

American University Beirut

Malek Tabbal

Konan University (Japan)

Ikurou Umezu

Fukuoka University Atsushi Kohno

Army Research Lab P. Wijewarnasuriya, Parvez Uppal, Fred Semendy

Sionyx, Inc. Martin Pralle, Jim Carey

Situational

Awareness

Hyperspectral weapon sights

Precision-guided munitions

Standoff Explosive Detection

Photovoltaics

DoD applications require Infrared light

Raman, LIBS SWIR Imaging

NVGs FLIR FLIR

THz

PGMs

eV

nm

Seekers Seekers

Range finders, Designators

Hyperspectral weapon sight

Si

InSb InGaAs

PbSe

HgCdTe

Ge

RT operation

Requires cooling Available Materials

1550 nm

Silicon-based IR optoelectronics

Silicon is…

Ubiquitous

Inexpensive

Well-characterized

Easy to integrate with readout circuitry

Non-absorbing for wavelengths > 1100 nm

+

-

Can we dope Si to see IR response?

Valence band

Conduction band

318

hν> EG

EG

hν< EG

e-

h

Valence band

Conduction band

e-

h

hν< EG

Valence band

Conduction band

hν< EG

Ordinary Si “Lightly” HD-Si “Heavily” HD-Si

Impurity conc. ↑, int. band broadens

e-

h

Hyperdoping: Create mid gap states

Chalcogen dopants in silicon

The Periodic Table of the Elements

I 2 B He

"'".'"" .._,hn• ) / 1!)':')4 4J•:l)

3 4 5 6 " R <) 10 ' l.i 1\e n c :\1 0 F Ne

l ,oh"n ~nl lotn ......... n rto" v ... .,.... ' "'h"' ~)""'"' ' "" i: .'>-11 '/.!11.!1 :>2 J(!.~l t 11-'o " ' H.{ooj ((' II,'NMil:~z :;~;. p•,)7

I I 12 I '' ·' 14 15 H• 17 I X

Na Mg AI Si p s Cl Ar ... ..... .... ':f"'"" ....... ,.,., '··:·:~ .. ""''t'lro)'• : ....... <1•0) •"'• ( '(;>•

12.'Jb'>:'":l l<IJtJ.s-J 2C..<;~ J JJ8 j t\:1737 J::Jt(o:i :t~A~l:' J.'J!."''~

I 'J 20 21 ,, <• 2:~ 24 25 2() 27 2X 29 3(1 31 32 :;,, 34 35 3(•

K Ca Sc T i v Cr .\·In Fe Co l\i C 11 Zn Ga Gc As Sc Br Kr (,, ... ,,, v.· .. ,,." '''"'"" v. '~""" • ltr.~""'' ..... ,.?_ ... ·~ .... .._ • . t .. ! t)i<(~ ·;.u <-•""'' '""''""""' ............ .::,, ... .,,.

"··~ " "'' :.'>'1" " .!').1:~>113 4!l/J:'!' 4-I.')JS!.'!tl ~:'.~!>? S.I!.'J4 1~ ~ J.')<JQJ ~-1.'/Jl!(Jol') 55.~! J~.·;:>JZ!IO !~.(1'):04 (o),S¥.o ()5 • .!') {o')::-2:l ; ;u :J N.'ll l 7~.'J6 i').'Xl~ ,i)~l)

·~ .~ I 3R :19 40 4 1 42 41 44 45 46 47 4~ 41) 50 51 52 53 54

Rb Sr y Zr Nb Mo Tc Ru Rh Pd Ag Cd Tn Sn Sb Te 1 Xe ll<olo~"·" Su.~""'' ~IM"tl y,_,, .. ,., .............

''"'"~""' ..... .,~ . " YoiJ>w.,., n ll ,ol o•o ,.,~ . .-.. ~, "- t :M .. , , ''''"'' ... ·' •'" •J ·~ ·" .... '"""'"" x .... ...

~ . .v..;~ 117.1!:; .ilL'J!l~!iS '}1.?24 'J! .'JI:Mt!. ')$.'.14 ( ')II \ 101 .tJ: 1(12.~'[•.$$0 h•f>A:i: W:' . .i(.._~ 11!.411 1 14.111~ l!K:U! !2 1.7(1(: :::6.'}1);44~ nu~·

55 56 57 !2 7J 74 i S "76 77 'JK 79 K(l ~ I 82 ~· ,> R5 R6 Cs Ra T.a H f Ta \\' Re Os Tr 1'1 Au Hg Tl Pb Ri Po At Rn r.-:., .. n:o~ .. ,, .............. ''"''I''" r,,,.,..,,.. T'h'>J$11> • k "eool ot> n .,... ,,., loll .... ,\.,;,,, ( h iJ . ....,,.,,. .,..1'1 ..... 1...-ol "'"'"''' ">'""'" J.W ~OO) II""'

U.!.90!iU n•-'2' n .j(.'J+)jS r:'~.:w l!ii).Y.I:''i !l~:!. :N l lv.o.::.:J:' (";11/2:! 1 ~:!.2 !. :' l'i$.0:'~ IW1.~z65!l :i:OIJ.$;> :::o..t:!.!!J.) ::07.2 ZC« .\Mt•:!:i .!t!9 !!I OJ f:!Z:!•

87 ~8 ~9 104 105 106 107 10~ 109 llO Ill 112 113 114 F'r Ra i\ C Rf' Db Sg llh Hs IVIt

r ... ,._ .. ., tt..J,.,. ..... , ....... lla.-h.::ru-J,. •. :-.;, .. ,, Sulu:ti"• 3:cinono ~:. ..... ~>~.; .. .,.;.,. i1:!Ji o:::.H::• ( 2:!7:. ~(•I I ;:U~o.:) {!6Ji (~ (':= :· !Zi.l$ 1 (:! ti(l) ;1(l;l) m::> .:.:~·:·

58 59 60 61 62 63 64 65 66 67 68 69 70 7 1 Ce T•r Nd Pm Srn F.u Gel T b Dy Ho F.r Tm Yb Lu ......... h ·->•:<bni•n. l4c>-t-ni ,.., t>.or.c .. ~U.. :t ... ., ..... £ .......... O.Jol,;,,., ;....;;...,. :>....---..... l-l;looion, Z:l:i .o• : tu!un • .. , •• otw .. t .,. .• tr.l

1-KU J() 1-kl.')t:l:"{o:i 14U4 IH$ 1 l.'CI.:lll l ! l :)M UJ.25 J jb.'J?5:f~ 1(:2.! 0 I M.:•:Jt•~1 1(0:'. :::6 l(IK,'JHl l J]J!:Jof l :'of.$67

90 91 92 9'' • J 94 95 96 97 98 99 100 101 102 103 Th Pa u :Xp Pu Am Cm Bk Cf Es Fm Md No Lr

Th:nom l'n·:o.o.•ioiun u ......... s'""'"""' r: . ~., ..... ,\~~~~~;,. ~~~ l!ul<:loon \:Ojc:,,., ,., e;. ...... -. .,.. l'.::n iu n r.::.nJ:I. .. ,.r. Ni:..t;.,, l·;;~';"' :B:!.fO:!X! ::::!J .t\3}~:-1 :!:.>~(!::.li'J IH71 l:! .:l:h ., , ,·; ,,;·, 1:!511 C5:! 'o !:i: ~ ~· (15~> !! !''il l

TECHNOWGY DRIVEN. WARRGHTER FOCUSED.

Valence band

Conduction band

Sulfur Selenium

318

614

110 188

371

92 82

248 307

593

206

390

214

116

All energies in meV

Janzen et al., Phys Rev B (1984)

Chalcogen dopants in silicon

11

32

me

V

Binding energies of chalcogen centers in Si

Spiked Black Silicon Harvard (Mazur)/ Sionyx

SF6

Si

Pulsed laser

Vacuum

system

Crouch et al, Appl Phys Lett (2004)

Spiked Black Silicon Harvard (Mazur)/ Sionyx

SF6

Si

Pulsed laser

Vacuum

system

Crouch et al, Appl Phys Lett (2004)

p-Si

Si+Ch

300 n

m

Ion-implant chalcogen

(S, Se, Te) into p-Si (1)

Bob et al, submitted to J Appl Phys Kim et al, Appl Phys Lett (2006)

Tabbal et al, JVST B (2007)

Flat Black Silicon Harvard (Aziz)/ ARDEC

p-Si

Si+Ch

300 n

m

Ion-implant chalcogen

(S, Se, Te) into p-Si (1) Pulsed-laser melting (PLM)

“heals” implant damage

Crystalline Si,

supersaturated in Ch, n-

type

ns laser,

~1.7 J/cm2

(2)

Bob et al, JAP (2010) Kim et al, Appl Phys Lett (2006)

Tabbal et al, JVST B (2007)

Flat Black Silicon Harvard (Aziz)/ ARDEC

Ar ion laser (CW)

488 nm

1.2 W

Relay-image w/pinhole

Lenses

Vacuum

chamber

Motorized

stage

λ/2 plate

Fast

photodiode

Oscilloscope

Nd:YAG laser

1064/532/355/266 nm

4 ns pulse duration

Benet Labs’ Black Silicon setup

Structure Optoelectronic

Properties

Absorption

Electronic

properties

Device

Properties

6.1 6.2

Characterization Logical Flow

• Dopant profile

• Surface roughness

• Crystallinity

• Local dopant

environment

• Absorption vs.

wavelength

• Depth profile

• Modeling

• Carrier sign,

concentration,

mobility, lifetime

• Hall effect

• Photoconductivity

• Spectral responsivity

• Quantum Efficiency

• IV curves

• Gain

• Detectivity

• Noise Equivalent

Power

• Dark current

0 100 200 300

0.00E+000

2.00E+020

4.00E+020

6.00E+020

8.00E+020

1.00E+021

con

cen

tra

tio

n (

cm

-3)

depth (nm)

as-implanted (SIMS)

1 shot (SIMS)

1 shot (calculation,

vevap

=0 nm/s)

1 shot (calculation,

vevap

=0.27 nm/s)

Bob et al, JAP (2010)

BUT, as laser shots ↑, vevap↓

Structure

Dopant depth profile evolution

Major questions

How does absorption

occur?

Is the excitationmobile?

How far can the excitation

travel?

Experimentalapproaches

Direct optical probes

Transport measurements

No free carriers are generated

No carriers reach the contacts

No carriers are collected

Obstacles to detection

A photon is absorbed

A mobile carrier is

generated

The carrier reaches a contact

The carrier is collected

Path to detection

Photoexcitationmeasurements

Our approach to studying

hyperdoped silicon

Absorption

Absorption

Winkler, Ph.D. thesis, Harvard (2010)

U US ARIIIIY ft~ ·v IIDEC~

photon energy (eV)

1 25 3 2 1 0.5 . .---r-r-----.---------~~----

Q)

g 1.00 ro -e-@ 0.75 .0 ro

"@ N 0.50 ro E ~

0 0.25 c

A = (1 - R - T) I (1 - R)

fs-laser doping , ,

lon implant+PLM doping

,..,1020 em""' chalcogens

silicon w fer

S.Si

S:Si

o ~------~~------~--_.~--~

0 1 2 wavelength (J.Im)

3

TECHNOWGY DRIVEN. WARRGHTER FOCUSED.

800 1000 1200 14000.01

0.1

1

10

100

1000 Si diode

Si:S, 12V, no anneal

wavelength (nm)

Re

spo

nsiv

ity (

A/W

)

Sionyx ARDEC/Harvard

Responsivity comparison

Optoelectronic

Properties

Said et al, APL (2011)

Strong, broadband absorption… …but no device response

An apparent conundrum

Valence band

Conduction band

318

hν> EG

EG

hν< EG

e-

h

Valence band

Conduction band

e-

h

hν< EG

Valence band

Conduction band

hν< EG

Ordinary Si “Lightly” HD-Si “Heavily” HD-Si

Impurity conc. ↑, int. band broadens

e-

h

Possible reconciliation

Other Strategies to Try

Valence band

Conduction band

Valence band

Conduction band

Less dopant

Valence band

Conduction band

Change dopant

Move states out of

conduction band

Move states

deeper into band

gap

Valence band

Conduction band

Add dopant

Compensate

impurity band

Stakeholders Research Groups

The Larger Black Silicon Universe

ARDEC-Benet

Warrender

RPI

Persans

Harvard

Aziz

MIT

Buonassisi

Harvard

Mazur

MIT

Gradecak

MIT

Grossman

Illinois

Ertekin

Extended IR response,

optoelectronic

charazterization

Characterization of fs-

structured Black Silicon

First principles modeling

Sionyx

Pralle, Carey Commercialization

CERDEC-

NVESD

USMC

ONR

White Sands

Missile Range

ARDEC

System

X

X X

X X

X

X X

Digital

Nightvision

CLRF

DETECT,

CLRF

Airborne

Laser

Precision-

guided

23 ¼ Moon, March 30, 2012, 8:40PM

• Low cost 8” CMOS manufacturing • Low Noise (Read noise ~2 e/pix)

(Dark Current <8e/pix/frame) • Low Power (300 mW @ 800x600)

• Compact Size • TRL 6 imaging device • TRL 6 wafer process

[email protected], 978-922-0684x127

Imaging from UV to NIR/SWIR

SiOnyx

Black Si

Si CCD Gen 3 I2

Starlight

illumination

Vis NIR SWIR

SiOnyx IR CMOS: Black Silicon enhanced imaging

Black Silicon Symposium

• Held in Albany, NY

• August 9-10

Outreach

Black Silicon Quarterly

• News and recent black silicon goings-on

• Send an email to

[email protected] to be

added to distribution

Summary and Outlook

• Laser hyperdoped “black” silicon can be made by two different

approaches

• Similar properties

• “Flat” black silicon easier to study

• Strong sub band gap absorption

• High EQE out to 1200 nm

• ARDEC seeks to extend strong device response to 1700 nm

• Fundamental and practical questions abound

[email protected]

BACKUP SLIDES

Research interests at Benet

Extending black silicon’s IR response

Characterizing the properties of ns-spiked black Si

Exploring broader slice of parameter space

Non-chalcogen dopants, thick layers, 5 ns pulses, non-

UV wavelengths

Increasing process cleanliness

Black Si photovoltaics

Laser/tool Purpose Capabilities

Ekspla NL313 Laser melting 532 nm/ 355 nm

800/500 mJ output

5 ns pulse duration

Coherent I-306 Surface

reflectivity

514/488/458 nm

2.4/1.8/0.42 W output

CW

Resonetics Excimer

system

Laser melting 248 nm

400 mJ output

20 ns pulse duration

Vacuum chamber with

motorized stage

Wafer-scale clean

processing

150 mm Si wafer

processing

Dual-beam FE-

SEM/FIB

TEM sample

prep, High-res

imaging

System spec pending

Assets

Gain is spatially inhomogeneous Optoelectronic

Properties

Gain is spatially inhomogeneous

1V 4V 12V

Optoelectronic

Properties

…but the story gets even weirder Optoelectronic

Properties

Microwave reflectivity

No detectable photoconductivity in the Si:S layer!

V

1. IR photon absorbed below junction

2. e- accelerated across junction

e-

h

Gain layer

IR absorbing layer

3. More e- created by collisions

Gain without

photoconductivity? Optoelectronic

Properties

XTEM lattice image of PLM’d material

U US ARIIIIY ft~ ·v IIDEC~

TECHNOWGY DRIVEN. WARRGHTER FOCUSED.

U US ARIIIIY ft~ ·v IIDEC~

Data were converted to signal per (pump photons per second)

photoinduced , microwave

reflectivity

pump energy per photon

Pump power 1-Reflectance

--Signal/ {pump

photons per second)

CD.a Cept1n Ceprg ( Cepo )x(photons! ~ec ) x ('I) ----- - = · = Ceprl] photo._n_s_/ s_ec __ P_h-...otons~~/~s=ec~~p:h~o:to:n:s~/ s:e:c ___ ~p:h~ot:o~n:s /~s:e~c -~~2~-=

Constant dependent on apparatus not sample or pump

Taking t he rat io of two measurements removes t he influe nce of the expe rimental apparatus (C cancels out)

TECHNOWGY DRIVEN. WARRGHTER FOCUSED.