Annealing effects on the microstructural and optical properties of Hg0.7Cd0.3Te epilayers grown on CdTe buffer layers

Abstract

Listen

Translate article

nand p-type HgxCd1−xTe epilayers have many potential applications, such as infrared detectors, infrared photovoltaic detectors, and infrared focalplane technologies [1–3]. Even though HgxCd1−xTe epitaxial films at high temperatures have been grown by using liquid-phase epitaxy and metalorganic chemical vapor deposition methods for many years [4, 5], interdiffusion or intermixing problems have occurred due to possible cross-doping effect. Recently, p-type HgxCd1−xTe epitaxial films were grown at low temperature by using an in-situ doping process utilizing molecular beam epitaxy [6]. However, high carrier concentrations have not been consistently achieved in p-type HgxCd1−xTe epilayers grown by using in-situ doping [7]. Even though some work concerning the formation of p-type HgxCd1−xTe epilayers through in-situ annealing has been performed [8, 9], ZnTe or ZnSe capping layers were used to avoid surface degradation. Since the growth of capping layers on HgxCd1−xTe epilayers is a complicated process, the formation of p-type HgxCd1−xTe epilayers of high quality and without any capping layer by using in-situ annealing is still necessary. Since the electrical, microstructural, and optical properties of HgxCd1−xTe epilayers significantly affect the quality of high efficiency devices, studies of the physical properties of HgxCd1−xTe epilayers are indispensable when attempting to understand the performance of optoelectric devices based on HgxCd1−xTe epilayers. Furthermore, since thermal treatment is necessary for the fabrication of optoelectronic devices utilizing HgxCd1−xTe epilayers, the role of the thermal annealing is very important in achieving high-performance devices [9]. Therefore, studies of in-situ annealing effects on the electrical, microstructural, optical properties play a very important role in enhancing efficiency. This letter reports the effect of in-situ annealing on the electrical, microstructural, and optical properties of HgxCd1−xTe thin films which were grown by using molecular beam epitaxy (MBE), utilizing CdTe buffer layers on GaAs substrates. The carrier concentration and the mobility of the as-grown and the in-situ annealed Hg0.7Cd0.3Te epilayers were investigated by us-