Laser-Induced Modification of the Morphology and Defect Structure of Heterostructures Based on Detector-Grade CdTe Crystals

Abstract

The processes of laser manipulation of the defect-impurity system and laser transformation of the crystal morphology made it possible to increase the detection properties of CdTe-based structures with a Schottky barrier. The structural perfection of CdTe:Cl single crystals was assessed using high-resolution X-ray diffractometry. The contact efficiency depends both on the electrode material and the surface treatment of the CdTe crystal before its deposition, in addition, the characteristics of the formed electrodesemiconductor interface can be changed by various treatments. Irradiation of the surface of CdTe crystals or metal-CdTe structures with laser pulses led to a change in the morphology of the semiconductor surface, the formation and redistribution of defects in the surface region and modification of the characteristics of this region or interface. The effect of laser processing on the structure of impurity defects and electrical characteristics of X-ray/-detectors on Schottky diodes, developed by deposition of Ni and NiO on commercially available CdTe:Cl wafers, was studied. Using the methods of atomic force and scanning electron microscopy, the features of Ni and NiO thin films before and after laser irradiation were investigated. The effect of pulsed laser irradiation on Ni/CdTe and NiO/CdTe contacts and the mechanisms of transformation of their phase state has not been investigated; however, such processing of these Schottky contacts led to optimization of their electrical characteristics. It is shown that laser treatment of heterojunctions, both CdTe substrates and Ni and NiO films, can intentionally change the electrical properties and increase the sensitivity of Ni/p-CdTe/Au/Cu and NiO/p-CdTe/Au/Cu detectors. The effect of laser processing on the electrical and spectroscopic properties of CdTe-based Schottky diode X-ray/ detectors is also discussed.