The thermal stability of the silicon doping of (111)A GaAs, grown by molecular beam epitaxy under different As overpressures, is studied by electrical and photoluminescence measurements. Annealing treatments were performed at 1028 K for 8 hr in As‐poor conditions. It is found that the silicon doping of (111)A GaAs is unstable; annealing turns the doping fromptype tontype inp‐type doped samples and increases the compensation inn‐type doped samples. The role of the point defects in the process is discussed. ©1996 American Institute of Physics.