Electrical and optical properties of vacuum deposited lead telluride layers

Vacuum deposited polycrystalline PbTe layers are investigated. The carrier concentrations of the layers are stoichiometrically varied by controlling the partial pressure of the tellurium source during growth. The effects of this stoichiometric variation on the electrical and optical properties are reported. Measurements of Hall coefficient (R(H)), carrier concentration (p), resistivity (rho), conductivity (sigma), Hall mobility (mu(H)), energy band gap (E(g)). and the temperature dependence of the mobility are made. The results indicate that a variation in the tellurium pressure during growth causes a corresponding change in the p-type carrier density and the energy band gap of the material. The change in the energy band gap, which is verified by observing the optical transmission properties of the layers, is explained by the growth doping model based on the compensation of the layers by atmospheric oxygen.