Surface morphologies of GaInP films grown on germanium (Ge) by metal–organic vapor-phase epitaxy (MOVPE) have been investigated for different pre-growth treatments. A high temperature pre-annealing to the Ge substrate results in a smooth surface of GaInP, while a surface degradation in the case of a low temperature annealing is obtained, which might come from an incomplete carbon and/or oxide desorption. An improved surface morphology of GaInP with silicon doping and with increasing Ge substrate misoriented angle was also observed, which indicates that the highly disordered GaInP film and the neat interface between Ge and GaInP were formed with the assistance of a high temperature pre-growth treatment.