Self-Diffusion in Isotopically Controlled Heterostructures of Elemental and Compound semiconductors

摘要

We report self-diffusion studies of silicon between 855 and 1388 deg C in highly enriched epitaxial ~28Si layers. diffusion profiles of ~30Si and ~29Si are determiend with high resolution secondary ion mass spectrometry (SIMS). The temeprature dependence of the Si self-diffusion coefficients is accurately descirbed with an activation enthalpy of 4.76 eV and a pre-exponential factor of 560 cm~2s~-1. The single activation enthalpy indicates that Si self-interstitials dominate self-diffusion over hta whole temperature range investigated. Self- and interdiffusion in buried Al~71GaAs/Al~69GaAs/~71GaAs isotope heterostructures with different Al composition is measured betwene 800 and 1160 deg C. Ga self-diffusion in AlGaAs and interdiffusion of Al and Ga at the AlGaAs/GaAs interface show that Ga diffusion decreases with increasing Al composition and that the interdiffusion coefficient depends linearly on Al concentration. Furthermore Al is found to diffuse more rapidly into GaAs than Ga diffuses in GaAs. the temperture dependence of Ga and Al diffusion in gaAs and of Ga diffusion in AlGaAs is described by a single activation enthalpy in the range of 3.6+-0.1 eV, but by different pre-exponential factors. Differences found for Ga and Al diffusion in GaAs and for Ga diffusion in AlGaAs with differnet Al concentrations are discussed.