Oxygen doping of AlGaAs and GaAs was investigated during Metalorganic vapor phase epitaxy growth using trimethylgallium. trimethylaluminum and AsH3 as growth sources and triethoxyarsine (As(OC2H5)(3)) as an oxygen doping Source. The electrical properties were studied using samples that were simultaneously doped,kith silicon and oxygen. In the case of GaAs. no oxygen doping was observed, For AlGaAs. the electron concentrations of the samples were reduced and by increasing the flow rates of As(OC2H5)(3) and At compositions. AlGaAs layers having a high resistivity could be produced. The incorporation of oxygen measured by secondary ion mass spectroscopy increased from 3.5 x 10(16) to 3.5 x 10(18) cm(-3) with increasing At composition in the layers. The leakage Current characteristics for oxygen-doped AlGaAs buffer layers vas also demonstrated. These results show that controlled oxygen doping for AlGaAs is successfully achieved using As(OC2H5)(3). (C) 2002 Elsevier Science B.V. All rights reserved.