The redistribution of Cr in doped semi-insulating material was studied by using secondary ion mass spectrometry. Marked Cr out-diffusion was observed from specimens which were annealed above 800C. The diffusion coefficient of Cr in GaAs could be described by:

D (cm2/s) = 6.3 x 105 exp[-3.4(eV)/kT]

J.Kasahara, N.Watanabe: Japanese Journal of Applied Physics , 1980, 19[3], L151-4