Investigation of Te-Doped GaAs Annealing Effects by Optical- and Channeling-Effect Measurements

Abstract

Backscattering and channeling-effect measurements with 2.5-MeV helium ions and measurements of the position of the infrared reflectivity plasma edge were used to investigate the absolute concentration of Te, the percentage of Te on lattice sites, and the free-carrier concentration in GaAs doped with [Te] ≈ 1019 cm−3 as a function of anneal. A 700°C anneal produced a reduction in carrier concentration [ne] by 20±2% (from the preanneal value of 5×1018 cm−3), and in the fraction of Te atoms on lattice sites. After an anneal at 1100°C, followed by quenching, [ne] rose to 7×1018 cm−3 while the Te distribution reverted to the original highly substitutional form. Throughout the experiment no measurable change from [Te]=9×1018 cm−3 was found. The correlations are discussed and related to existing models for anneal-dependent complexes.