Chemically-assisted ion-beam etching of (AlGa)As/GaAs: lattice damage and removal by in-situ Cl-2 treatment

We evaluated the lattice damage in Al0.4Ga0.6As/GaAs Single Quantum Well (S QW) structures caused by Chemically-Assisted Ion-Beam Etching (CAIBE) in co mparison with Ion-Beam Etching (IBE) and wet etching. The damage was analyz ed 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 de pth, BCl3/Cl-2-CAIBE (E-kin = 400 eV) damages to a depth of 10 nm. An in-si tu Cl-2-treatment (Cl-2-flow = 6 sccm, T-Substrate = 120 degrees C, p = 3 x 10(-4) mbar, without plasma) allows a pure chemical removal of the surface layer which was damaged by CAIBE. This combined process facilitates anisot ropic etching together with a lattice damage as low as with wet etching. (C ) 1999 Elsevier Science B.V. All rights reserved.