Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 32: Photovoltaic
HL 32.5: Vortrag
Mittwoch, 29. März 2006, 15:30–15:45, BEY 118
Carrier recombination dynamics in 1 eV band gap (GaIn)(NAs)/GaAs solar cell material as a function of epitaxial growth conditions and post-growth annealing processes — •Swantje Horst, Kristian Hantke, Sangam Chatterjee, Kerstin Volz, Wolfgang Stolz, and Wolfgang Rühle — Faculty of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, D-35032 Marburg, Germany
We measure time-integrated as well as time-resolved photoluminescence (PL) at room temperature of series of as-grown and post-growth annealed Ga0.92In0.08N0.03As0.97/GaAs epilayers grown by metal-organic vapour-phase epitaxy (MOVPE) using either trimethylgallium (TMGa) or triethylgallium (TEGa) as Ga precursors in combination with tertiarybutylarsine (TBAs) and 1,1-dimethylhydrazine (UDMHy). The samples are nominally undoped or intentionally doped with Mg (p-doping) or Te (n-doping) with doping levels typically used for solar cell applications. Post-growth thermal annealing significantly improves the optical quality of the (GaIn)(NAs) material. The PL of the p-doped samples show, at low excitation densities, an increased initial PL intensity and a slightly faster PL decay compared to the undoped samples, whereas the n-doped samples have a reduced initial PL signal and a much faster PL decay. The p-doped layers thus have a larger minority carrier lifetime and therefore a longer minority carrier diffusion-length. In addition, the PL-characteristics in particular of the as grown (GaIn)(NAs) material is improved by annealing with intense laser light. Possible reasons for this observation will be presented and discussed.