Modification of CdTe-HgTe defect substructure and carrier concentration bylaser irradiation

Studies of the structure defects arising in the HgTe, (Cd,Hg)Te and CdTe cr ystals under both ruby laser pulse irradiation of ms duration and change ca rriers concentrations profiles of the (Cd,Hg)Te near-surface layers disturb ed by laser were conducted. The threshold density of laser irradiation ener gy is defined, when it exceeds the structural defects are formed in a near- surface layer. The dislocation generation is connected with thermomechanica l stresses caused by large temperature gradients (up to 10 K/mu m) and nonu niform thermal crystal extension in the zone of laser pulse action. The cha nge carrier concentration profiles are studied by the held 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. (C) 1998 Published by Elsevier Science B.V. All rights reserved.