Process dependence of AlAs/GaAs superlattice mixing induced by silicon implantation

Abstract

Silicon implantation induced mixing of a 400‐Å period AlAs/GaAs superlattice grown by organometallic chemical vapor deposition is examined using secondary ion mass spectrometry and transmission electron microscopy. The depth dependence of Al and Si diffusion for a 180‐kV 3×10¹⁵ cm⁻² Si⁺ implant is measured as a function of implantation temperature, annealing temperature, and annealing time. The room‐temperature implanted sample exhibits a near‐surface mixing inhibition following anneal. No mixing inhibition is observed in samples implanted at higher temperatures. Si segregates rapidly into the GaAs layers during the anneal. Si diffusion is inhibited near the peak of the implant. Mixing depths and defect distributions are strongly dependent on the processing conditions employed. The results are consistent with a divacancy model for Al diffusion.