Selective wet oxidation and selective wet etching of Al(Ga)As/GaAs and their use in device fabrication

Results are shown demonstrating that the selective characteristics of wet oxidation and wet etching in Al(Ga)As/GaAs structures strongly depend on the Al compositions. Especially, the oxidation length decreases rapidly with decreasing AlAs thickness in the range of <80 nm and oxidation nearly stops at a thickness of similar to 11 nm. The oxidation rate of AlxGa1-xAs decreases quickly with decreasing Al composition, providing a high degree of oxidation selectivity. In addition, the studies on the wet etching of AlxGa1-xAs/AlyGa1-yAs (x <0.5, y >0.7) structures show that the AlGa1-xAs layer is selectively etched in the citric acid/H2O2 solution and the AlyGa1-yAs layer in deionized H2O/buffered HF solution. Finally the selectivity of both wet oxidation and wet etching is applied to the VCSEL fabrication.