Photoelectric properties of Si2Te3 single crystals

Silicon telluride Si2Te3, which crystallizes in a hexagonal layer defect structure, is a p-type semiconductor with an optical band gap Eg = 2.2 eV. The electrical conductivity at 300 K shows strong anisotropy. The hole mobility parallel to the c-axis is very low (μ∥︁ = 2 X 10-3 cm2/Vs). The analysis of the photocurrent as a function of generation rate and temperature indicates a trap level Ey — Ev = 0.45 eV and a broad energy distribution of recombination centers ER — Ev ≈ ≈ 0.9 eV above the valence band. The hole lifetime is found to reach a constant value τ = 10-7 s at high generation rates. These results are in good agreement with a broad luminescence spectrum exhibiting a maximum at 1.1 eV. From response time measurements a trap density Y = 1017 cm−3 is deduced.