Phosphorus and antimony in GaAs as tracers for self-diffusion on the arsenic sublattice

For investigating arsenic self-diffusion, phosphorus (P) and antimony (Sb) were used. New P and Sb in-diffusion experiments show the same behavior as P and Sb interdiffusion experiments. This is in contradiction to results fr om the literature. By means of transmission electron microscopy we observed a phase transformation to polycrystalline GaAs1-xPx at the surface under e xperimental conditions similar to those described in the literature. This l eads to a penetration depth much higher than for the P in-diffusion without this phase transformation. The new diffusion coefficients of the P and Sb in-diffusion above 900 degrees C are in the same range as the interdiffusio n coefficients and self-diffusion coefficients from As-tracer diffusion. Fr om this result we conclude that P and Sb have tracer properties for arsenic self-diffusion in GaAs. Measurements of the diffusion coefficients at diff erent As-vapor pressures revealed that As self-diffusion is dominated by As self-interstitials. Furthermore, we performed annealing experiments on dif ferently doped samples. There is no indication of a Fermi-level effect. Hen ce, As self-diffusion is governed mainly by neutral defects. Between 900 an d 1100 degrees C, we obtain an Arrhenius expression D-As(SD)=75 exp(-4.4 eV /kT)cm(2)/s, which describes As self-diffusion. The P in-diffusion values b elow 900 degrees C show a weaker temperature dependence, which indicates a changeover to a different diffusion mechanism. (C) 2000 American Institute of Physics. [S0021-8979(00)06601-9].