Abstract
We report the observations of nonstructural acousto-injection luminescence from metallized LiNbO3 wafers. The samples under study are the X-or Y-cut wafers with the silver paste electrodes on opposite surfaces. The thickness is 1-2 mm and other linear dimensions are in the range of 2 to 25 mm. Experiments are done at room temperature in the MHz-frequency range. Mainly the fundamental shear ultrasound modes are excited in the samples. Experimentally are measured the spectra of nonstructural acousto-injection luminescence, photo-luminescence spectra, acousto-electric properties, X-Ray diffraction under NAIL. The nonstructural acousto-injection luminescence and other effects appear above certain threshold amplitude of the acoustical strain that is about 10(5). The involvement of the microstructural non-uniformities in the effects observed is experimentally identified by the photo-luminescence of point defects taken from different micro-regions of the samples. The data are explained in terms of the considerable acoustic stresses and piezoelectric fields that are capable injecting charge carriers from the metal contacts into a crystal.