Fabrication and characterisation of solid-phase crystallised plasma-deposited silicon thin films on glass for photovoltaic application

Abstract

n-type poly-Si films with very large grains, exceeding 30 ?m in width, and with high Hall mobility of about 71.5 cm2/Vs are successfully prepared by the solid phase crystallization (SPC) technique on glass through control of the PH3(2% in H2)/SiH4 gas flow ratio. A significant improvement in the efficiency of p-type poly-Si thin-film solar cells is demonstrated through the improvement of the material quality of the n+ emitter layer. A high-rate (up to 146 nm/minute) conformal PECVD a-Si:H deposition process is established. SPC poly-Si thin films prepared from high rate deposited (146 nm/min) a-Si:H films are shown to have the same (or even slightly better) crystal quality than those deposited at lower deposition rate (~20 nm/min). In addition, a highly absorbing p-type ?-FeSi2(Al) semiconductor film is successfully integrated with n-type SPC poly-Si on glass, creating a functional solar cell device.