Highly selective etching (>150) of GaAs over Al0.2Ga 0.8As with low GaAs etch rates (<50 Å/s) can be performed using a newly developed CA/H2O2/H2O etchant (CA = citric acid: H2O of 1:1 by weight). Modulating the H 2O2 content in this etching system can overcome the weakness of previously nonselective etching inference using CA/H 2O2 + H2O, and solve the problem of excessive GaAs etch rates (>100 Å/s) associated with using traditional CA/H 2O2 solutions. When applied to pseudomorphic high electron mobility transistors (PHEMTs), high etching uniformity and a smooth surface (rms roughness of only 2.01 Å) are observed during gate recessing; the gate leakage currents are then suppressed, suggesting the applicability of the CA/H2O2 /H2O system to fabricating PHEMTs.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Science(all)
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering