Electrical Conduction and Switching in Amorphous Semiconductors

Abstract

Electrical conductivity, thermally stimulated current, plaotoconductivity and switching effect have been investigated in amorphous semiconductors of As-Te, As-Te-Ga and As-Te-Ga-Ge-Si chalcogenides. The electrical conductivity σ is found to be expressed by σ=σ₀exp (Δ E/k T) with conductivity activation energy Δ E ranging from 0.12 eV to 0.47 eV depending on the compositions in the temperature range of 300°K to 500°K. A memory effect appears in conductivity vs. temperature curves of such a specimen that shows memory effect in the switching experiments; high conductivity state at T=500°K remains unchanged down to room temperature. Thermal quenching gives the initial low conductivity at room temperature. From thermally stimulated current measurements, the energy levels of trapping centers are found to be about 0.18 eV and 0.23 eV. Switching experiments are made in thin and thick specimens at room temperature.