ELECTRICAL AND OPTICAL-PROPERTIES OF VACUUM-DEPOSITED LEAD-TELLURIDE LAYERS

Vacuum deposited polycrystalline PbTe layers are investigated. The car rier concentrations of the layers are stoichiometrically varied by con trolling the partial pressure of the tellurium source during growth. T he effects of this stoichiometric variation on the electrical and opti cal properties are reported. Measurements of Hall coefficient (R(H)), carrier concentration (p), resistivity (rho), conductivity (sigma), Ha ll mobility (mu(H)), energy band gap (E(g)). and the temperature depen dence 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 gr owth doping model based on the compensation of the layers by atmospher ic oxygen.