Quantum wells of various widths were grown by using organometallic vapor phase epitaxy. An upper layer of GaAs was thermally oxidized at 450C, and rapid thermal annealing was performed at 950C under Ar. Photoluminescence data showed that an order of magnitude increase in interdiffusion occurred in the oxide-covered quantum wells, as compared to uncovered ones. However, when a thin layer of Al was evaporated over the oxide layer before rapid thermal annealing, the rate of interdiffusion was reduced by more than an order of magnitude as compared with that of uncovered quantum wells. The interdiffusion slowed because the oxide, which comprised mainly Ga2O3, was quickly reduced by Al during rapid thermal annealing so as to form atomic Ga plus Al2O3. The latter formed over the quantum wells and trapped the free Ga as interstitials in the GaAs. The excess Ga interstitial concentration reduced the group-III vacancy concentration, and this reduction then slowed the interdiffusion rate.

Native defect engineering of interdiffusion using thermally grown oxides of GaAs R.M.Cohen, G.Li, C.Jagadish, P.T.Burke, M.Gal: Applied Physics Letters, 1998, 73[6], 803-5