Determination of arsenic diffusion parameters by sulfur indiffusion in gallium arsenide

Indiffusion profiles of sulfur in gallium arsenide were determined by secon dary ion mass spectroscopy. In order to evaluate the shape of the profiles, a set of coupled reaction-diffusion equations was solved numerically. From the simulated nonequilibrium indiffusion profiles of sulfur, which diffuse s into gallium arsenide via the kick-out mechanism, both the diffusion coef ficient and the equilibrium concentration of arsenic self-interstitials wer e simultaneously determined. Transmission electron microscopy revealed that , due to an arsenic supersaturation, extrinsic dislocation loops have forme d. The Fermi-level effect is more pronounced at lower diffusion temperature s and provides an additional driving force for the loop formation, agreeing well with the occurrence of larger faulted loops at a diffusion temperatur e of 950 degreesC rather than at 1100 degreesC. The complex behavior of the sulfur indiffusion can be quantitatively described by taking into account extended defects. (C) 2000 American Institute of Physics. [S0021-8979(01)01 901-6].