Cathodoluminescence studies of MOCVD grown, e-beam pumped, II-VI laser structures

摘要

Single and multiple quantum well structures composed of CdSe wells and ZnSe barriers have been grown onto GaAs (001) substrates, using Metal Organic Chemical Vapour Deposition, for the production of laser chips which will emit in the green / blue-green part of the electromagnetic spectrum. A purpose built electron-beam excitation system has been developed with the ability to excite luminescence in the sample and monitor its wavelength and intensity from the edge of the laser cavity. Low temperature (4K) scanning cathodoluminescence has been used to optimise the materials growth and structural parameters for laser applications. This paper presents results from this study which has allowed the determination of the optimum thickness and growth parameters for the CdSe well and the ZnSe buffer layers. Atomic scale non-uniformities of the quantum well thickness, on a lateral scale of 10 to 20/xm, have been observed using monochromatic cathodoluminescence imaging. Evidence of sample lasing is presented.