Hole centers in GaSe

Abstract

A systematic investigation of hole centers acting in p‐GaSe single crystals has been carried out by means of the following methods: (i) dark conductivity measurements as a function of temperature; (ii) space‐charge‐limited‐current measurements extended from 77 to 300 °K; (iii) thermally stimulated‐current measurements as a function of temperature. A series of hole centers has been found with energy depths ranging from 26 to 400 meV from the valence band and densities of about 10¹³ cm⁻³. A complete summary of the energy levels present in the forbidden gap of GaSe up to 600 meV from the valence band is given. A comparison is made between the results of this work, previously reported data, results obtained by Hall‐effect versus temperature measurements, and data quoted by other authors. Finally, the origin and nature of all the hole centers are discussed, taking into account their possible connections with the defective structure of GaSe.