Intrinsic defects in ZnO and GaN crystals

Abstract

The kinetics of defect formation in the system of a crystal with a nonmetal component in the activated gas phase has been investigated. The data obtained has made it possible to develop physicochemical methods of regulating the defect-formation processes depending on the adsorption-desorption-crystallization equilibrium on the surface of a crystal. A kinetic model of defect formation in the A II B VI and A III B V compounds is proposed. Results of the kinetic analysis of the intrinsic defects in the ZnO and GaN compounds are presented. The photoluminescence spectra of GaN films annealed in a flow of nonmetal-component radicals (atoms) have been considered.Introduction. Broad-band semiconductor compounds belonging to the A II B VI and A III B V groups have been intensively investigated in recent years. These investigations were carried out, first of all, with the goal of developing effective light sources, including stimulated-radiation sources operating in the short-wave visible range. The most promising material among the A II B VI compounds is ZnSe (E g = 2.7 eV). It was reported in some works [1-3] that there are laser diodes based on ZnSe, operating to advantage in the blue-green range, that have been developed. Great hopes are also pinned on ZnO (E g = 3.46 eV), because this material shows an effective exciton luminescence in the near-ultraviolet region of the spectrum and possesses an exciton binding energy of up to 60 meV, which makes it possible to obtain a stimulated radiation at high temperatures. In [4,5], light-emitting diodes based on ZnO were developed. The production of high-quality gallium nitride films of n-type and p-type conduction had made it possible to develop effective light-emitting diodes and semiconductor lasers operating in the blue region of the spectrum [6,7].The synthesis of crystals with a definite composition of intrinsic defects is a complex technological problem. The intrinsic atomic defects substantially influence the optical and electrical properties of the A II B VI and A III B V compounds -radiation spectra and type of conduction. The intrinsic defects in doped semiconductors determine the solubility of an impurity, the structure of the impurity centers, and the mechanism of conduction compensation. In this connection, it is important to develop methods of postgrowth treatment that would allow one to control the deviation from the stoichiometry of these compounds.We have developed a technology of thermal treatment of A II B VI (A III B V ) compounds in nonmetal-component radicals (atoms), called the gettering radical-beam epitaxy [8]. The possibility of conduction-type inversion has been demonstrated with the example of ZnS (ZnSe, ZnO).In the present work, the kinetics of defect formation in the system of a crystal with a nonmetal component in the activated gas phase is considered and results of the kinetic analysis of an ensemble of intrinsic point defects in ZnO and GaN are given.Experimental. The thermodynamic and kinetic factors responsible for the tendency of the A II B ...

Structural and optical properties of ZnO films obtained on mesoporous Si substrates by the method of HF magnetron sputtering

“…Earlier, we showed in [26] that the band at 370.2 nm in ZnO is caused by the recombination of excitons at the neutral acceptor of zinc vacancy, and 402 nm is associated with radiative transitions in the conduction band or the acceptor, where there is intrinsic defect of the zinc vacancy V Zn with a depth of~0.3 eV above the ceiling of the valence band. We also showed in [27] that the concentration of zinc vacancies, depending on the conditions of heat treatment, can be 10 17 to 10 19 cm −3 . This is supported by the data of [28], wherein the authors also associated the observed band of 401 nm with a zinc vacancy.…”

Systematical, experimental investigations on LiMgZ (Z = P, As, Sb) wide band gap semiconductors

“…Binary semiconductors can be realized from wide to low band gap (ZnO to HgTe). However very often the compounds show intrinsic defects [2,3] or indirect band gaps [4], which makes a search for new semiconducting compounds necessary. However ternary semiconductors were not investigated systematically up to date.…”