Effects of Electric Fields on Cathodoluminescence from II-VI Quantum Well Light Emitting Diodes

Abstract

Effects of electrical bias on the cathodoluminescence (CL) have been investigated for a blue 1I-VI quantum well (QW) light emitting diode structure of ZnCdMgSe, lattice-matched to InP. In CL wavelength scans, the observed effects include largely reversible changes in QW CL intensity and wavelength and changes in cladding CL intensity. In CL time-based scans, the QW CL intensity showed both immediate and long term changes with bias. Irreversible, degradationrelated decreases in QW CL intensity were also observed. Effects of bias on CL were modeled by calculating the rates of carrier production by electron bombardment and the resulting electron and hole currents with different applied bias fields. These model calculations do not explain many of the experimental observations, because the model does not include effects of bias on carrier escape and redistribution in the QW and effects of bias on generation and transport of atomic scale defects.