Transport properties of vapor grown orthorhombic sulfur crystals

Abstract

Crystals of orthorhombic sulfur have been grown from the vapor phase and their electrical transport properties are compared with those of CS2 solution grown and natural sulfur crystals. The temperature dependence of the hole drift mobilities shows that the transport mechanism is trap controlled. The trap depth in the vapor grown crystals is 0.22 eV which is the same as that for the solution grown crystals. However, the trap density (1017 cm-3) in the vapor grown crystals is 1-4 orders of magnitude higher than found in the solution grown crystals. The trap is attributed to a structural defect in both types of crystal. The electron transport is by an intermolecular hopping process3 which becomes trap controlled at lower temperatures. The trap depth and density are 0.4±0.1 eV and 1014 cm-3 respectively. Thermally stimulated conductivity measurements have been made on vapor grown, solution grown and natural crystals. Peaks at 0.17 eV and 0.2 eV are correlated with electron and hole mobility activation energies respectively. © 1967.