Title :
High-efficiency drift-field thin-film silicon solar cells by liquid-phase epitaxy and substrate thinning
Author :
Zheng, Guang Fu ; Zhang, Wei ; Shi, Zhengrong ; Thorp, David ; Green, Martin A.
Author_Institution :
Centre for Photovoltaic Devices & Syst., New South Wales Univ., Sydney, NSW, Australia
Abstract :
Silicon films of 20-35 μm thickness were grown by LPE on electrically inactive heavily doped p++-type CZ silicon substrates from In/Ga solutions. A Ga doping gradient was introduced throughout the film to produce a drift-field in the base of the solar cell, thus enhancing the effective minority-carrier diffusion length and increasing the long-wavelength response. An independently confirmed efficiency of 16.4% was achieved on an LPE drift-field thin-film silicon solar cell with total cell area of 4.11 cm2. Substrate thinning, combined with light-trapping, is demonstrated to improve the long-wavelength response of cells and further increase the efficiency of the LPE cells. Cell efficiency increased by a factor of up to 23.7% when thinned to a total cell thickness of 30 μm
Keywords :
carrier lifetime; elemental semiconductors; liquid phase epitaxial growth; minority carriers; semiconductor epitaxial layers; semiconductor materials; semiconductor thin films; silicon; solar cells; substrates; 16.4 percent; 20 to 35 mum; Ga doping gradient; In/Ga solutions; LPE growth; Si; Si:Ga; drift-field; heavily doped p++-type CZ silicon substrates; high efficiency solar cells; light-trapping; liquid-phase epitaxy; long-wavelength response; minority-carrier diffusion length; substrate thinning; thin-film silicon solar cells; Doping; Epitaxial growth; Optical films; Photovoltaic cells; Semiconductor films; Semiconductor thin films; Silicon; Substrates; Temperature; Transistors;
Conference_Titel :
Photovoltaic Specialists Conference, 1996., Conference Record of the Twenty Fifth IEEE
Conference_Location :
Washington, DC
Print_ISBN :
0-7803-3166-4
DOI :
10.1109/PVSC.1996.564224
