Wet Oxidation Process to Al_0.98Ga_0.02As Layer for the Vertical-Cavity-Surface-Emitting-Laser Fabrications

Abstract

To study the wet oxidation process and mechanism in the Vertical-Cavity-Surface-Emitting-Laser (VCSEL) fabrications, a special material structure was designed and grown by the Metal-Organic Chemical Vapor Deposition(MOCVD) method. The samples formed by photolithography and dry etching were subjected to wet oxidation for different time, and the oxidation degree was determined by the surface morphology and the cross-sectional structure. In this study, a linear tendency was revealed between oxidation depth and oxidation time during a relatively short oxidation period, then it transformed into parabolic tendency and gradually became saturated with increasing oxidation time. Moreover, it was found that the oxidation rate of Al 0.98 Ga 0.02 As was higher than that of Al 0.9 Ga 0.1 As layer by one order of magnitude, and the speed of oxidation processing was accelerated as the Al 0.9 Ga 0.1 As layer thickened. Finally, the lateral oxidation process of Al 0.98 Ga 0.02 As layer in the confined space was interpreted by a modified one-dimensional Deal-Grove model.