Photoluminescence and Hall‐effect measurements on neutron transmutation doped liquid‐phase‐epitaxial GaAs layers were performed. The obtained results clearly point out that at least a part of the Ge atoms introduced by transmutation of Ga leave their original lattice site behaving as acceptors. The probable cause of these displacements are the recoils during &ggr; and &bgr; emissions from the unstable Ga isotopes.