Effects of irradiation on the electrical and optical properties of PbSnTe

Radiation effects on the electrical conductivity, Hall mobility, and carrier density were studied on three different types of p-type PbSnTe samples. One type (sample 1) was vapor-grown with an initial carrier density of ∼4 &time; 10¹⁶ cm⁻³, and was irradiated with 30-MeV electrons at 78°K. Another type (sample 2), which was cut from a solid-state recrystallized boule and then annealed to lower its carrier concentration to ∼8 &time; 10¹⁷ cm⁻³, was also irradiated with 30-MeV electrons at 78°K. The other type of specimen (sample 3) was an epitaxially deposited thin film on a BaF2 substratum, with a carrier concentration of ∼4 &time; 10¹⁷ cm⁻³. It was electron-irradiated at 9°K and subsequently gamma- and neutron-irradiated at 78°K. Temperature dependence of the optical transmission for sample 3 was performed to determine the radiation dependence of the energy bandgap.