High-quality a-Si:H growth at high rate using an expanding thermal plasma

An expanding thermal arc plasma is used to deposit amorphous hydrogenated silicon films. The thermal arc is operated in an argon–hydrogen mixture and SiH4 is injected downstream in the plasma jet. In this contribution, we report the results of substrate temperature variation keeping the arc settings constant. It is observed that the growth rate is more or less independent of the substrate temperature at a value of 7 nm s−1 and that the hydrogen content decreases with increasing substrate temperature to a value around 7% at 350 °C. The defect density decreases with increasing substrate temperature to a solar grade quality value of around 5×1015 cm−3. These results are compared with results obtained using a classical RF glow discharge and are interpreted through a deposition model based on the SiH3 radical which is first physisorbed on the hydrogenated surface, diffuses to a dangling bond and then sticks.