Amplitude dependent damping in HgI2 wide band gap semiconductor

Amplitude dependent damping in crystals is considered as one of the methods of mechanical spectroscopy for investigating different mechanisms of dislo cation microplasticity. A short review of the amplitude dependent damping s tudies in semiconductors is presented. A new acousto-optic experimental tec hnique for studying a dislocation point defect interaction developed over t he last several years is described. Experimental data of photoacoustic inve stigations of HgI2 single crystals obtained in a wide amplitude range at fr equencies of longitudinal vibrations of about 100 kHz are reviewed. More re cent results an presented as well. Besides, acousto-electric and acousto-op tic (for a band of photoluminescence spectrum) effects which result from a high amplitude ultrasonic treatment (HAUT) with the amplitudes from the amp litude dependent damping range illustrate the possibilities of the techniqu e. A model of an electron or hole trapping center which transforms in a dis location pinning point during the sample illumination is assumed to be the most convenient to explain the experimental data. Under the influence of HA UT, one can destroy (due to dislocation depinning) the center which consist s of the dislocation, point defect (it is, surely, a lattice, iodine or mer cury, vacancy or interstitial) and the trapped electron or hole. A binding energy between the dislocation and the photosensitive pinning point defect has been estimated by displacement under the HAUT of specific points in the luminescence excitation spectrum. A possible practical use of HAUT for a r estoration of performance of gamma-ray HgI2 detectors is briefly discussed. (C) 2000 Elsevier Science S.A. All rights reserved.