GaNxP1-x and related materials are promising for light-emitting and solar cell devices grown on silicon, but have shown less-than-ideal performance. The transport properties of these materials, though, can be greatly influenced by growth conditions. We study the effects of metal-organic chemical vapor deposition growth conditions of GaN0.02P0.98 on the unintentional incorporation of carbon and hydrogen and the room-temperature photoluminescence (PL) decay lifetime. We find the incorporation of carbon to be dominated by either the gallium source (trimethylgallium or triethylgallium) or the nitrogen source (dimethylhydrazine), depending on growth conditions. The PL decay lifetime is found to be correlated to both the carbon and hydrogen concentration. Growth temperature, gallium source, group V flux, and growth rate can all strongly influence the carbon and hydrogen impurity incorporation, and thus, the PL lifetime. In the samples with the lowest hydrogen and carbon concentrations (similar to10(17) cm(-3)), we have achieved room-temperature PL lifetimes as high as 3.0 ns. Published by Elsevier B.V.