Electrical properties of evaporated silicon films

The Hall coefficient and conductivity of silicon films vacuum deposited on 0° and 60° sapphire at 850°C to 1050°C were measured from 100°K to 550°K. Films made from 0.094 Ω-cm p type and 1 Ω-cm n type silicon sources were prepared by electron bombardment heating of the source in a vacuum of 5 x 10⁻⁷ to 10⁻⁶ torr. The orientation and crystallinity of the films were investigated using electron diffraction. It was found that defects in the films introduced both donor and acceptor levels. The heavy compensation thus produced in films deposited at lower temperatures lead to a very low hole concentration. All films were p type at room temperature showing that the acceptor levels slightly dominated the donor levels. The films deposited on 0° sapphire indicated fewer defects than those deposited on 60° sapphire. At high temperature (> 950°C) doping of the silicon by aluminum atoms from the substrate was appreciable. The Hall mobility of the films made from the p type source material decreased with increasing temperature of deposition. This apparent anomaly is explained by the use of the polycrystalline film model suggested by Volger (1950).Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat