Diffusion mechanism of implanted Be in GaAs

Abstract

The transient enhanced diffusion of low and high dose implanted beryllium in undoped gallium arsenide during post‐implant rapid thermal annealing in the temperature range of 700–900 °C for 60–240 s has been studied and successfully simulated by the kick‐out diffusion model, involving singly positively charged Be interstitials and doubly positively charged Ga self‐interstitials. Using the “plus one” approach for Ga interstitial generation after implantation with the local Ga interstitial sink concept as well as the appropriate initial and boundary conditions for involved mobile species, and taking into account Fermi‐level and built‐in electric field effects, the obtained partial differential equations have been solved numerically by means of an explicit finite difference method. The thermal equilibrium concentrations and the diffusivities of Be and Ga interstitials, all as a function of temperature, have been deduced from the fits of the experimental profiles obtained by the secondary ion mass spectrometry technique. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)