Effects of Hot Wire Temperature on Properties of GeSi:H Films with High Hydrogen Dilution by Hot-Wire Chemical Vapor Deposition

GeSi:H films are prepared by hot-wire chemical vapor deposition (CVD) with high hydrogen dilution, DH=98%. Effects of hot wire temperature (Tw) on deposition rate, structural properties and bandgap of GeSi:H films are studied with surface profilemeter, Raman spectroscopy, Fourier transformed infrared spectroscopy, and UV-VIS-NIR spectrophotometer. It is found that the deposition rate (Rd) goes up with increasing of Tw, but increasing rate of Rd declines when Tw⩾1 550 °C. High Tw is beneficial to the formation of Ge-Si, but it has little effect on relative contents of the hydrogen bonds (Ge-H, Si-H, etc.) in the films. In the Tw range of 1 400–1 850 °C, the maximum bandgap of the GeSi:H films is 1.39 eV at Tw =1 450 °C and the band gap decreases with Tw increasing when Tw⩾1 450 °C.