THE EFFECT OF Ge CONTENT ON THE OPTICAL AND ELECTRICAL PROPERTIES OF a-SiGe:H THIN FILMS

Abstract

The effect of Ge content on the optical and electrical properties of Si-Ge-H thin films deposited by HWCPECVD

had been investigated. The Si- Ge-H films ware grown on corning glass 7059 substrate using 10% diluted
GeH4 and SiH4 gas mixture, respectively. The GeH4 gas flow rate was varied from 2.5 to 12.5 sccm, while the flow
rate of SiH
was kept constant at 70 sccm. The results showed that the deposition rate of Si-Ge-H thin films was
increases with the increasing of GeH4 gas flow rate. Beside, the Ge content in the film also increased, and the optical
band gap decreased. The dark conductivity of Si- Ge-H films was relatively constant, whereas the photo ’s
conductivity decreased with increasing of Ge content.