Self-Diffusion in gallium arsenide

The self-diffusion of arsenic in gallium arsenide has been studied over the temperature range 1000 to 1075δC using radiotracer techniques.⁷⁶As was diffused into GaAs samples at known arsenic pressures in sealed capsules. After diffusion, layers were removed from the surface using anodic oxidation followed by oxide dissolution. Diffusion profiles were obtained by measuring the⁷⁶As concentration in each sectioned layer by γ-radiation counting. Diffusion coefficients at P_{As 2} = 0.75 atm and over the temperature range 1000 to 1050δC were found to be 5.2 × 10^-16cm²s^-1 to 1.5 × 10^-15 cm²s^-1, leading to an activation energy of the order of 3.0^± 0.04 eV and a pre-exponential factor of 5.5 × l0^-4 ± 2.4 × 10^-4 cm²s^-1. Diffusion coefficients at P_{As 2} =3.0 atm were found to be 5.5 × 10^-15 and 9.8 × 10^-16 cm² s^-1 at 1050 and 1075δC, respectively. Results are discussed in terms of native point defect equilibria with the arsenic gaseous phase, and with respect to other work. It is deduced from our observed arsenic pressure dependence of the arsenic diffusivity that the most likely diffusion mechanism