Title :
Carrier Transport in Microcrystalline Silicon-Germanium Alloy Films and Solar Cells
Author :
Matsui, T. ; Ogata, K. ; Ozawa, T. ; Isomura, M. ; Kondo, M.
Author_Institution :
Res. Center for Photovoltaics, Nat. Inst. of Adv. Ind. Sci. & Technol., Ibaraki
Abstract :
We report on carrier transport properties of microcrystalline silicon-germanium (muc-Si1-xGex:H) alloy films and solar cells prepared by SiH4/GeH4/H2 glow-discharge. Conductivity and Hall-effect measurements reveal a transition from weak n-type to strong p-type conduction for x>0.75, while the photoconductivity decreases monotonically with x, indicating an increased photocarrier recombination upon Ge incorporation. In fact, spectral response of p-i-n solar cells exhibits poor carrier collection behavior and strong thickness dependence as the x increases in the i-layer. Nevertheless, quantum efficiencies can be raised remarkably by applying an external bias voltage. As a result, a 0.9 mum-thick muc-Si0.6Ge0.4:H solar cell yields a photocurrent of 27.4 mA/cm2 with infrared sensitivities greater than those of thicker muc-Si:H solar cells
Keywords :
Ge-Si alloys; Hall effect; carrier lifetime; hydrogen; photoconductivity; semiconductor junctions; semiconductor materials; semiconductor thin films; solar cells; 0.9 micron; Hall-effect; Si1-xGex:H; bias voltage; carrier transport; glow-discharge; microcrystalline silicon-germanium alloy films; n-type conduction; p-i-n solar cells; p-type conduction; photocarrier recombination; photoconductivity; photocurrent; quantum efficiency; solar cells; Conductivity measurement; Germanium alloys; Germanium silicon alloys; PIN photodiodes; Photoconductivity; Photovoltaic cells; Radiative recombination; Semiconductor films; Silicon alloys; Silicon germanium;
Conference_Titel :
Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on
Conference_Location :
Waikoloa, HI
Print_ISBN :
1-4244-0017-1
Electronic_ISBN :
1-4244-0017-1
DOI :
10.1109/WCPEC.2006.279798
