Title :
Optimization of LPE-grown high efficiency GaAs solar cells
Author :
Bett, A. ; Cardona, S. ; Ehrhardt, A. ; Lutz, F. ; Welter, H. ; Wettling
Author_Institution :
Fraunhofer-Inst. fuer Solare Energiesysteme, Freiburg, Germany
Abstract :
AlGaAs/GaAs heteroface solar cells were processed using the LPE etchback-regrowth method. Cells of 1 cm2 area with a single AR coating exhibit an average efficiency of 21% AM1.5 and peak values of 22.3% AM1.5. A series of 30 cells with emitter thickness varying between 0.2 and 4 μm was analyzed with respect to doping concentration by CV profiling measurements. The influences of Al and Zn concentration on the depth and profile of the emitter were investigated with the help of a concentration-dependent diffusion model. The homogeneity of the layers with respect to thickness and minority carrier recombination was analyzed by photoluminescence mapping and photoluminescence decay measurements. It was found that the optimal emitter thickness for the LPE etchback-regrowth process lies between 1.5 and 2 μm
Keywords :
III-V semiconductors; aluminium compounds; electron-hole recombination; gallium arsenide; liquid phase epitaxial growth; minority carriers; photoluminescence; semiconductor epitaxial layers; semiconductor growth; solar cells; 0.2 to 4 micron; 21 to 22.3 percent; AM1.5; Al; AlGaAs-GaAs; CV profiling measurements; GaAs; LPE etchback-regrowth method; LPE-grown; Zn; concentration-dependent diffusion model; emitter depth; emitter profile; emitter thickness; heteroface solar cells; high efficiency; layer homogeneity; minority carrier recombination; optimal emitter thickness; photoluminescence decay; photoluminescence mapping; solar cells; thickness; Epitaxial growth; Epitaxial layers; Etching; Gallium arsenide; Molecular beam epitaxial growth; Photoluminescence; Photovoltaic cells; Substrates; Thickness measurement; Zinc;
Conference_Titel :
Photovoltaic Specialists Conference, 1991., Conference Record of the Twenty Second IEEE
Conference_Location :
Las Vegas, NV
Print_ISBN :
0-87942-636-5
DOI :
10.1109/PVSC.1991.169197
