Chemically-assisted ion-beam etching of (AlGa)As/GaAsf lattice damage and removal by in-situ Cl_2 treatment

摘要

We evaluated the lattice damage in Al_0.4Ga_0.6As/GaAs Single Quantum Well (SQW) structures caused by Chemically- Assisted Ion-Beam Etching (CAIBE) in comparison with Ion-Beam Etching (IBE) and wet etching. The damage was analyzed by measuring the Photoluminescence (PL) of the SQWs as a function of the etch depth. While IBE (E_kin = 400 eV) causes a damaged region of 27 nm depth, BCl_3/Cl_2-CAIBE (E_kin = 400 eV) damages to a depth of 10 nm. An in-situ Cl_2-treatment (Cl_2 -flow = 6 sccm, T_Substrate = 120℃, P = 3 × 10~(-4) mbar, without plasma) allows a pure chemical removal of the surface layer which was damaged by CAIBE. This combined process facilitates anisotropic etching together with a lattice damage as low as with wet etching.