Study On A-Si: H Films Prepared By Dielectric Barrier Discharge Plasma-Enhanced Hot-Wire CVD

Dielectric barrier discharge (DBD) plasma enhanced hot wire chemical vapor deposition (HWCVD) technique remains characteristic features of Plasma enhanced (PE)-HWCVD with high deposition rate, whereas film damage caused by high-energy ions bombardment is avoided. In this paper, DBD-PHWCVD was used to deposit a-Si:H thin films, the properties of Si films were analyzed by Raman scattering spectroscopy, transmission spectroscopy, X-ray diffraction, Scanning electron microscopy and Hall, including:the structural and electrical effect of different DBD peak voltage, deposition pressure, doping concentration, distance between hot-wire and substrates on Si film's structure were studied systematically, the results have been shown:1. The deposition rate of Si films increased with increasing of the gas pressure. At the same time when the peak voltage DBD increased, the deposition rate increased.2. With the deposition pressure increased, the optical band gap of the Si film decreased. And the optical band gap will further decrease with increasing of the pressure, or importing of DBD, or increasing of DBD peak voltage.3. With the deposition pressure increased, or with taking effect of DBD, or the DBD peak voltage increased, the crystallization ratio are between 58-68% and overall trend increased. The results showed from the crystallization ratio, or with taking effect of DBD, or the DBD peak voltage increased, the structure of the film did not show amorphous due to ion bombardment, but has been enhanced crystallization ratio.4. With the pressure increased under 80Pa, the film grain size is from 6.3nm down to 4.4nm (down 30%). With taking effect of DBD, or the DBD peak voltage increased, the grain size is reduced. In the 100Pa, because H atom etching weakened, DBD peak voltage is a leading role in dissociation of gas-phase molecule, so the grain size increased.5. With the B2H6 doping concentration increased, the deposition rate increased. When B2H6 concentration is less than 7%, the carrier concentration and electrical conductivity increased; when B2H6 concentration more than 7%, the carrier concentration and conductivity decreased. 6. With the distance Dsc between hot-wire and the substrate increased, the deposition rate and the carrier concentration decreased. Because the number of H atoms increased, the surface etching effect increased, so the film growth rate reduced.