Nonstructural acousto-injection luminescence in metalized lithium niobate wafers

Abstract

We report the observations of nonstructural acousto-injection luminescence (NAIL) 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 NAIL, photo-luminescence spectra, acousto-electric properties, X-Ray diffraction under NAIL. The NAIL 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.

Point defects in ZX-cut Lithium niobate and Lithium tantalate and their influence on acousto-electric properties

“…[1][2][3] Lithium tantalate (LiTaO3, abbreviated as LT) is a perovskite crystal with a similar crystal lattice as Lithium niobate (LN). It has unique piezoelectric and ferroelectric properties with applications in nonlinear optics, 4 infrared sensors, 5 terahertz detectors, 6 cell phones, 7 optical waveguides, 8 SAW substrates, 9 and others.…”