Effect of Laser Irradiation on Low‐Temperature Photoconductivity and Photoluminescence Spectra of Gallium Selenide

Abstract

Features of photoluminescence (PL) and photoconductivity (PC) spectra, taken at 4.2 to 60 K, of GaSe crystals of stoichiometric composition and grown with an excess and with a lack of Ga atoms are analyzed. It is shown that the presence of excessive Se atoms in the matrix of GaSe crystals results in the formation of centres where triplet excitons are bound. Excessive Ga atoms formed in a crystal both, in the process of its growth and under the effect of laser irradiation give rise to regions with another polytype composition (γ‐modification). The presence of such (γ‐polytype) regions is shown to produce packing defects whre localization of excited electron states (n > 1) occurs. An effect of PC signal increase with increasing exposure dose is found, which is attributed to the formation of acceptor centres.

Optical and Electrical Properties of p-GaSe Doped with In

“…8) Moreover, the origins of such defects have been investigated using GaSe crystals with excess Ga or Se atoms. 9,10) The level due to interstitial Se atoms was formed near the energy region as free and bound exciton lines in the PL spectrum.…”

Defect Luminescence in Some Layered Binary Chalcogenide Semiconductors

“…Impurity levels in other binary III-VI chalcogenides such as InSe [27,28] have also been studied using photoluminescence techniques. While much can be learned from near band edge emission of semiconductors, recombination luminescence from states lower in energy (i.e: deep level photoluminescence) can also be very informative in the information it provides about impurity levels and defect states [29]. Typically, both the temperature and excitation intensity dependence of the PL peak energies, linewidths and intensities are analyzed to identify the nature of the transitions involved in the recombination processes.…”