Effect of radio frequency bias on the optical and structural properties of nanocrystalline SiC films deposited by helicon wave plasma enhanced chemical vapor deposition

摘要

Nanocrystalline cubic silicon carbide thin films have been fabricated by helicon wave plasma enhanced chemical vapor deposition (HWP-CVD) on Si and Corning 7059 glass substrates using the mix plasma of SiH_4, CH_4, and H_2. The effect of negative radio-frequency (rf) bias voltage on the optical and structural of the deposited hydrogenated nanocrystalline SiC (NC-SiC:H) films has been investigated by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-VIS) transmittance spectroscopy, and photoluminescence (PL) spectroscopy. It is found that with increasing the negative rf substrate bias, the NC-SiC:H thin films become denser and have fewer defects. The PL measurement indicates that all the deposited film present a strong light emission at the room temperature under an excitation of the 370 nm line of a Xe lamp. The blue-green PL peak can be ascribed to quantum confine effect of small size SiC nanocrystal in the film.