Chemically-assisted ion-beam etching of (AlGa)As/GaAs. Lattice damage and removal by in-situ Cl2 treatment

We evaluated the lattice damage in Al(0,4)Ga(0,6),As/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 (Ekin = 400 eV) causes a damaged region of 27 nm depth, BCl3/Cl2 -CAIBE (Ekin = 400 eV) damages to a depth of 10 nm. An in-situ Cl2- treatment (Cl2-flow = 6 sccm, Tsubstrate = 120 deg C, p = 3 X 10(exp -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.