Epi-n-IZO thin films/Æ1 0 0æ Si, GaAs and InP by L-MBE––a novel feasibility study for SIS type solar cells

High quality epitaxial indium zinc oxide (heavily indium oxide doped) (epi-n-IZO) thin films were optimized by laser-molecular beam epitaxy (L-MBE) i.e., pulsed laser deposition (PLD) technique for fabricating novel isoand hetero-semiconductor–insulator–semiconductor (SIS) type solar cells using Johnson Matthey ‘‘specpure’’grade 90% In2O3 mixed 10% ZnO (as commercial indium tin oxide (ITO) composition) pellets. The effects of substrate temperatures, substrates and heavy indium oxide incorporation on IZO thin film growth, opto-electronic properties with Æ1 0 0æ silicon (Si), gallium arsenide (GaAs) and indium phosphide (InP) wafers were studied. As well as the feasibility of developing some novel models of isoand hetero-SIS type solar cells using epi-IZO thin films as transparent conducting oxides (TCOs) and Æ1 0 0æ oriented Si, GaAs and InP wafers as base substrates was also studied simultaneously. The optimized films were highly oriented, uniform, single crystalline approachment, nano-crystalline, anti-reflective (AR) and epitaxially lattice matched with Æ1 0 0æ Si, GaAs and InP wafers without any buffer layers. The optical transmission T (max)P 95% is broader and absolute rivals that of other TCOs such as ITO. The highest conductivity observed is r 1⁄4 0:47 10 X 1 cm 1 (n-type), carrier density n 1⁄4 0:168 10 cm 3 and mobility l 1⁄4 123 cm/V s. From optoelectronic characterizations, the solar cell characteristics and feasibilities of fabricating respective epi-n-TCO/Æ1 0 0æ wafer SIS type solar cells were confirmed. Also, the essential parameters of these cells were calculated and tabulated. We hope that these data be helpful either as a scientific or technical basis in semiconductor processing. 2004 Elsevier Ltd. All rights reserved. PACS: 68.55; 81.15.G; 73.60.F; 72.20; 72.80.E