Microcrystalline Silicon Prepared by Hot-Wire Chemical Vapour Deposition for Thin Film Solar Cell Applications

The hot-wire deposition of muc-Si:H at low substrate and filament temperatures improves the material quality substantially. At a substrate temperature of 285degreesC and a filament temperature of 1530degreesC we prepared microcrystalline films with a spin density of N-s = 1 x 10(16)cm(-3) measured by electron spin resonance (ESR) and an oxygen and carbon concentration of 2 x 10(18)cm(-3) at a deposition rate of 2.5 Angstrom(.)s(-1). From infrared spectroscopy we calculated a hydrogen content of 5% in the best films. The spectra did not show absorption from SiO modes. which is typical for nonporous material. By incorporating this material into microcrystalline solar cells. we achieved an initial efficiency of 7%. By reducing the substrate temperature, an even higher efficiency of 7.5% was obtained.