Finite element simulations of compositionally graded InGaN solar cells
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Finite element simulations of compositionally graded InGaN solar cells G.F. Brown a,b,* , J.W.AgerIIIb, W.Walukiewicz b , J.Wua, b,a Advisor: H.C. Kuo Reporter: H.W. Wang Solar Energy Materials & Solar Cells 94 (2010) 478– 483 a Department of Materials Science&Engineering , University of California , Berkeley,California94720,USA b Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley,California94720,USA
description
Finite element simulations of compositionally graded InGaN solar cells . G.F. Brown a,b ,* , J.W.AgerIIIb , W.Walukiewicz b , J.Wua, b,a. a Department of Materials Science&Engineering , University of California , Berkeley,California94720,USA - PowerPoint PPT Presentation
Transcript of Finite element simulations of compositionally graded InGaN solar cells
Finite element simulations of compositionally graded InGaN solar
cells G.F. Brown a,b,* , J.W.AgerIIIb, W.Walukiewicz b, J.Wua,b,a
Advisor: H.C. KuoReporter: H.W. Wang
Solar Energy Materials & Solar Cells 94 (2010) 478–483
a Department of Materials Science&Engineering , University of California , Berkeley,California94720,USAb Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley,California94720,USA
1. Introduction
2. Properties of InxGa1-xN used in simulations 3. Simulation results
Outline:
4. Conclusions
Broad band InN - 0.7eV GaN - 3.42eV
Cheep fabrication process Grown on Si substrates by a low temperature
processHigh effiency
Advantage
DisadvantageIndium composition (<30%)
P-type doping
High absorption
Large lattice mismatch between InN and GaN alloysValence band discontinuity
Introduction
Properties of InxGa1-xN used in simulations
Caughey–Thomas approximation
Absorption Coefficient
APSYS simulation toolSelf-consistancePoisson equationCarrier drift diffusion equation
InGaN - wurtzite crystal structureFermi level at the InGaN/GaN - un-pinnedNo reflection and light trapping effects No surface recombination losses
Simulation results
P-GaN
In0.5Ga0.5N
100nm
1mm
AM 1.5
Optical carrier generation rate
p-GaN
n-In0.5Ga0.5N
100nm
1mm
AM 1.5
5x1018cm-3
1x1017cm-3
Band diagram
I–V curve
P-GaN
InXGa1-XN
AM 1.5
Efficiency
Fill factor and Short-circuit current V.S. Indium composition
p-GaN
n-In0.5Ga0.5N
100nm
1mm
AM 1.5
5x1018cm-3
1x1017cm-3
50nm1x1017cm-3
n-InXGa1-XN
Band diagramEfficiency
p-GaN
n-In0.5Ga0.5N
100nm
1mm
AM 1.5
5x1018cm-3
1x1017cm-3
n-InXGa1-XN
Efficiency
Band diagram
p-GaN
n-In0.5Ga0.5N
100nm
1mm
AM 1.5
5x1018cm-3
1x1017cm-3
50nm1x1017cm-3
n-InXGa1-XN
Minority hole life time in InGaN layer
p-GaN
n-In0.5Ga0.5N
100nm
1mm
AM 1.5
5x1018cm-3
1x1017cm-3
50nm1x1017cm-3
n-InXGa1-XN
p-Si
n-Si
n-Si
5x1019cm-3
1x1016cm-3
1x1019cm-3
100nm
495mm
5mm
Efficiency
Conclusions
Simulate graded p-GaN/InxGa1-xN heterojunctionGraded layer between
hetrojunctionImprove valence band discontinuity
Doping and widthLight doping & thin layer → high efficencyDouble junction – InGaN/Si28.9% → high efficiency & low cost substrate
