Selective wet oxidation and selective wet etching of AI(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 ∼11 nm. The oxidation rate of Al _xGa _1-xAs decreases quickly with decreasing Al composition, providing a high degree of oxidation selectivity. In addition, the studies on the wet etching of Al _xGa _1-xAs/Al _yGa _1-yAs ( _x <0.5, y >0.7) structures show that the Ali _xGa _1-x As layer is selectively etched in the citric acid/H ₂O ₂ solution and the Al _yGa _1-yAs layer in deionized H ₂O/buffered HF solution. Finally the selectivity of both wet oxidation and wet etching is applied to the VCSEL fabrication.