SELECTIVE OXIDATION OF BURIED ALGAAS VERSUS ALAS LAYERS

We report significant differences between the properties of buried oxi des converted from AlGaAs and AlAs layers using selective wet oxidatio n. Layers of AlxGa1-xAs with x greater than or equal to 0.96 exhibit c rystallographic dependent oxidation rates, while for layers with x les s than or equal to 0.92 the oxidation rate is isotropic. Mesas contain ing partially oxidized layers of AlAs are unstable to rapid thermal cy cling and exhibit excessive strain at the oxide terminus, while mesas containing partially oxidized layers of AlGaAs are robust and lack evi dence of strain, Finally, the oxidation of AlGaAs layers, rather than AlAs, is found to provide robust oxide apertures for reliable vertical -cavity surface emitting lasers. (C) 1996 American Institute of Physic s.