Some properties of intrinsic and phosphorus doped amorphous silicon thin films

Abstract

The dark conductivity σ_D and the photoconductivity σ_Ph of intrinsic and n-type (phosphorus doped) a-Si: H films prepared by rf glow discharge of silane gas has been studied. The samples have been prepared under different experimental conditions which include change of rf power, substrate temperature and dopant concentration. The most significant result has been the change in dark conductivity and photoconductivity with the change of rf power within a limited range of 2 to 30 Watts. As shown by infrared spectroscopy the chances in σ_D and σ_Ph with rf power are mainly due to the change of hydrogen content. The appearance of a kink in σ_D vs 1/T plot (at T' with higher slope at T>T') has been explained as due to the effect of statistical shift of the Fermi level E_F.