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 a-SiGe:H thin films deposited by HWC-PECVD had been investigated. The a-SiGe:H films ware grown on corning glass 7059 substrate using 10% diluted mixture of GeH 4 and SiH 4 gases, respectively. The GeH 4 gas flow rate was varied from 2.5 – 12.5 sccm, while the flow rate of SiH 4 was kept constant at 70 sccm. The results showed that the deposition rate of a-SiGe:H thin films increased by increasing of GeH 4 gas flow rate. In addition, the Ge content in the film increased and the optical band gap decreased. The dark conductivity of a-SiGe:H films were relatively constant, whereas the photo conductivity decreased with increasing of Ge content.