The mixed Group V ternary alloyGaAs1−yPy(y<0.17)has been grown by metal organic vapor phase epitaxy and doped with oxygen using the oxygen precursor, diethylaluminum ethoxide[C2H5OAl(C2H5)2].Controlled oxygen doping was accomplished over the range of0<y<0.17.Deep level transient spectroscopy measurements reveal the presence of several oxygen-related deep levels. These levels, previously found in GaAs:O, vary with alloy composition over the investigated range. An additional deep level, most probably associated with the presence of misfit-related defects, has been identified. Photoluminescence performed on the oxygen-doped samples indicates that band edge emission is reduced and lower energy emission features are introduced over the wavelength range of 1000–1200 nm as a result of oxygen incorporation. ©1997 American Institute of Physics.