COMPOSITION CHANGE OF INDIUM OXIDE FILM BY TRIETHYLGALLIUM IRRADIATION PREPARED FOR IN-SITU SELECTIVE EPITAXY USE

Selective epitaxy of GaAs was examined by the chemical beam epitaxy (CBE) technique on indium oxide masks. The indium oxide films were prepared in vacuum with an alternating supply of trimethylindium (TMIn) and H2O2. The irradiation of triethylgallium (TEGa) and AsH3 on the indium oxide films was performed to examine whether or not GaAs deposition takes place on the oxide films. After irradiation for 30 min above 450-degrees-C, drastic change in the chemical composition of the oxide films was observed. That is, indium atoms in the oxide films were replaced by gallium atoms. It was found that gallium atoms released on the oxide surfaces by TEGa decomposition promoted the sublimation of indium oxide through reduction. Two probable reactions are proposed for this sublimation process. The difference between indium oxide and gallium oxide in the suppression of TEGa decomposition is briefly discussed as well. The investigation shows that selective epitaxy of GaAs on the indium oxide masks can be achieved by the CBE technique using TEGa and AsH3, although the sublimation of the oxide limits the film thickness of epitaxial GaAs.