SI - Peidong Yang Group - University of California, Berkeley

SupportingInformationfor:
SolutionPhaseSynthesisofIndiumGalliumPhosphideAlloyNanowires
Nikolay Kornienko1, Desiré D. Whitmore1, Yi Yu1, Stephen R. Leone1,2,4, Peidong
Yang*1,3,5,6
1
Department of Chemistry, 2Department of Physics and 3Department of Materials Science Engineering,
University of California, Berkeley 94720, United States
4
Chemical Sciences Division and 5Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley
CA 94720, United States
6
Kavli Energy Nanosciences Institute, Berkeley, California 94720, United States
*
Correspondence to: [email protected]
TableofContents:
FigureS1.TEMIn/Gagrowthseeds.............................................................................................................................2
FigureS2.TEMofInPandGaPNWs.............................................................................................................................2
FigureS3.Compositionanddiametercontrol.........................................................................................................3
FigureS4.XRDofInxGa1‐xPNWs..................................................................................................................................4
FigureS5.ElectrondiffractionofInxGa1‐xPNWs...................................................................................................5
FigureS6.RamanspectraofInPandGaP..................................................................................................................6
FigureS7.UV‐VisabsorptionofInxGa1‐xPNWs.....................................................................................................7
FigureS8.EELSanalysis....................................................................................................................................................8
FigureS9.EELSdatafitting..............................................................................................................................................9
FigureS10.IndividualNWPL......................................................................................................................................10
FigureS11.NormalizedPLIntensity........................................................................................................................11
1
FigurreS1.STEMimageofIn//Gaalloyseed
ds(A)andth
heircorrespo
ondingEDSeelemental
mapss(B,C).
nIn,Ga,andP
Pprecursorssweremixed
dtogetherin
FigurreS2.TEManalysisofproductswhen
onestepbeforeheatingrevealsthatseparateInPandG
GaPNW’sforrm.EDSanallysisofwiress
dBshowspu
ureInPwhileecorrespondinganalysis ofwiresDan
ndCindicateespureGaP.
Aand
2
ositionoftheeresultingNW
Wsiscontroolledbythep
precursorrattioofTMIn
FigurreS3.Compo
andT
TEGa(A)and
dthediameteeriscontrolleedbythetottalprecursorrconcentration(B).TEM
imageesofNWsof
f increasingd
diameter(C‐F
F).
3
FigurreS4.XRDoffInP,InxGa1‐xxP,andGaP((A‐D)indicattethattheNW
Wsallconsisstofprimarilly
theziincblendecry
ystalstructure.
4
ondiffraction
nofInP,InxGa
G 1‐xPandGaaPNWsrotattedperpendiculartothe
FigurreS5.Electro
[011]]planeswith
hcomposition
nindicated((A‐E)revealssthattheNW
Wsgrowinth
he
[111]]directionSim
mulatedelecctrondiffracttionpattern((F)forzincbllendeInPvieewed
perpeendiculartotthe[011]planesmatcheestheexperim
mentaldata.Asimplestrructural
modeel(G)showsseverallowM
Millerindex planesoftheezincblendecrystalstruccture.
5
nspectraof((A)InPNWsandwaferan
nd(B)GaPN
NWsandwaffershow
FigurreS6.Raman
consistentphonon
nmodespossitionsandlin
neshapes.
6
d
FigurreS7.UV‐VissabsorptionspectrumforindirectbaandgapNWss(A)showsaabelowband
gapaabsorptionan
ndonlyashaarpriseinabsorptionateenergiesgreaaterthantheedirectband
gapo
ofthemateriaal.Incontrasst,directbandgapNWs( B)featureasharprisein
nabsorption
attheebandedge.
7
FigurreS8.EELSaanalysisofth
heNWswasp
performedu singamonocchromatedZ
ZLPwitha
FWHM
Mof0.17eV(A).Forpow
werlawfittin
ng(B,C)theb
backgroundw
wassubtracttedfromthe
rawd
dataandtheinelasticsign
nalwasextraacted.Bandggapextractio
onusingtheiinflection
pointtfromrawdaata(D)gaveslightlydiffeerentresults butthetrend
dofbandgap
pvs.
comp
positionwasconsistent(E
E).
8
FigurreS9.EELSo
onsetfittingo
ofGaP(A),In
nxGa1‐xP(B‐D
D)andInP(E
E)NWs.GaPaandInPEELSS
3/2
specttracanbeweellfittedwith
hindirectban
ndgap(E ))anddirectb
bandgap(E1//2)models
whileeInxGa1‐xPhaavecontributtionsfrombo
othdirectan
ndindirectbaandgaps.Astheindium
comp
positionisinccreased,theEELSdatareesemblesmooretheE1/2m
model,indicaatingagreateer
contrributionfrom
mthedirectb
bandgap.TheeEgdescribeestheextracttedbandgap
pvalue.
9
FigurreS10.PLm
measurementsscorrelatinggtothecomp
positionofin
ndividualNW
Wsweretaken
n
toobttainanexacttcomposition
n‐bandgaprrelation.The SEMimageo
ofanindivid
dualNW(A)
wasm
matchedwith
htheopticalimageoftheesameNWon
nasiliconsu
ubstrate(B)ttocorrelate
itsED
DSspectrum(C)andelem
mentalcompo
ositiontotheePLenergy((D).Thecom
mprehensive
measurementsarresummarizeedin(E)and
dfollowthessametrendasfigure5inthemaintexxt.
1
10
FigurreS11.PLin
ntensity,norm
malizedtoth
heNWvolum
me,wasusedasanotherm
methodto
pinpo
ointthedirecct‐indirectbaandgaptransition.SEMiimages(A)w
wereusedtomeasure
volum
meandcorreelatedtotheo
opticalimageeoftheNWoonasiliconssubstrate(B))andthePL
intensity(C).ThePLintensity
y,acquiredun
nderidenticaalconditionssforallsamp
ples,was
dividedbytheNW
Wvolumetogeneratetheenormalized
dPLintensityyvs.PLenerggydiagram
(D).T
Theyellowdo
ottedlinerep
presentstheexpectedPL
LintensityasstheΓvalleyymoves
higheerinenergytthantheXvaalley,whichsscalesas:
/
,whereB
Bisaconstan
nt
andE
EΓ(x)andEX(xx)arethebaandminimaaasafunction ofcompositiion.
1
11
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