Accurately nonselective and selective etching of GaAs/Al_(0.8)Ga_(0.2)As/AlAs structure for making air-gap cavity

摘要

We have demonstrated a wet etching technique capable of fabricating air-gap cavity. The process utilizes nonselective and selective etchants respectively to form air-gap cavity. The etching characteristics of GaAs/Al_(0.8)Ga_(0.2)As/AlAs structure in different nonselective and selective etchants are investigated. The volumetric 3:2:20 ratios of H_3PO_4/H_2O_2/H_2O solution and volumetric 600:1 ratio of DI water/buffered oxide [mixture of 7:1 NH_4F(36%)-HF(6.4%)] solution are better nonselective and selective etchants respectively. We have used this process technique to form a tunable air-gap cavity optical filter. The measure results of the transmission spectral show that the air-gap cavity has high optical quality. These simple etching processes can be applied to fabricate the air-gap cavity devices.