GaAs, GaP, and GaAs1−xPx films have been prepared by molecular beam epitaxy. The epitaxial temperatures without twins are found to be lower than 530 °C for GaAs and 550 °C for GaP with a depositiion rate about 100 Å/min. The crystallographic qualities of the deposited films are comparable to those of the crystals grown by LPE, and it is possible to control carrier concentration by simultaneous evaporation of dopant materials. The sticking coefficients of the dopants such as Sn, Mg, and Zn are measured and compared with the theoretical calculation. By simultaneous evaporation of As and P with Ga, GaAs1−xPx films are deposited epitaxially through all the molefractions.