We have systematically studied the dependence of the electrical properties of Si‐doped (311)A GaAs on the growth conditions in molecular beam epitaxy and have established a phase diagram for the conduction type as functions of the growth temperature and the V4/III flux ratio. A sharp boundary is observed for the transition between thep‐ andn‐type conduction, on both sides of which the activation efficiency of Si is close to unity. Furthermore, it is found that, in contrast to the case of the (111)A GaAs, the conduction‐type conversion in Si‐doped (311)A GaAs does not show a clear correlation with the macroscopic surface morphology, suggesting that the mechanism for the conduction‐type conversion in Si‐doped (311)A GaAs is different from that for the (111)A orientation. ©1995 American Institute of Physics.