Nonstructural acousto-injection luminescence in metalized lithium niobate wafers

TL;DR

This study reports nonstructural acousto-injection luminescence in metalized lithium niobate wafers, revealing how acoustic stresses and piezoelectric fields induce charge injection and luminescence at room temperature.

Contribution

It provides the first detailed experimental analysis of NAIL in LiNbO3 wafers, linking microstructural non-uniformity to luminescence effects and charge injection mechanisms.

Findings

NAIL observed above a threshold strain of 10E-5

Luminescence spectra linked to point defects and micro-regions

Charge injection driven by acoustic stresses and piezoelectric fields

Abstract

We report the observations of nonstructural acousto-injection luminescence (NAIL) from tantalized LiNbO3 wafers. The samples under study are the X cut or Y cut wafers with the silver paste electrodes on opposite surfaces. The thickness is 1 to 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 10E-5. The involvement of the microstructural non-uniformity 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.