Electron bombardment induced enhancement of luminescence from ZnCdMgSe quantum well light emitting diodes

Abstract

Electron bombardment enhancement of luminescence from ZnCdMgSe quantum well (QW) light emitting diodes has been studied by time-resolved and bias- and temperature-dependent cathodoluminescence (CL) spectroscopy and mapping. Effects of electron bombardment are seen as bright regions in CL images. The enhancement of CL intensity decays with time after electron bombardment for tens and hundreds of hours, and the rate of decay is faster for higher temperatures in the range studied, 20–200°C. We propose that the enhancement of QW CL intensity results from buildup of internal fields due to persistent charge trapping at pre-existing or electron bombardment created defects. A simple trapping-detrapping model involving two types of traps with different activation energies reproduces most aspects of the observed time and temperature dependence of decay of the luminescence enhancement.