Modification of CdTe–HgTe defect substructure and carrier concentration by laser irradiation

Abstract

Studies of the structure defects arising in the HgTe, (Cd,Hg)Te and CdTe crystals under both ruby laser pulse irradiation of ms duration and change carriers concentrations profiles of the (Cd,Hg)Te near-surface layers disturbed by laser were conducted. The threshold density of laser irradiation energy is defined, when it exceeds the structural defects are formed in a near-surface layer. The dislocation generation is connected with thermomechanical stresses caused by large temperature gradients (up to 10 K/μm) and nonuniform thermal crystal extension in the zone of laser pulse action. The change carrier concentration profiles are studied by the field effect method in electrolytes used in combination with layer-by-layer etching. The carrier concentration has its maximum for a depth h that increases when irradiation energy density increases. The possibility to form reproducibly in the near-surface region of CdTe crystals a layer with high dislocation density not changing the volume properties opens new prospects in using such layers for gettering undesirable dopants and structure defects.