Papers Published

1. Tan, T.Y. and You, H.M. and Yu, S. and Goesele, U.M. and Jager, W. and Zypman, F. and Tsu, R. and Lee, S.-T., Disordering and characterization studies of ⁶⁹GaAs/⁷¹GaAs isotope superlattice structures: the effect of outdiffusion of the substrate dopant Si, Defect Engineering in Semiconductor Growth, Processing and Device Technology Symposium (1992), pp. 873 - 80 .
   (last updated on 2007/04/10)

   Abstract:
   Undoped ⁶⁹GaAs/⁷¹GaAs isotope superlattice structures grown by MBE on n-type GaAs substrates, doped by Si to ~3×10¹⁸ cm^-3, have been used to study Ga self-diffusion in GaAs by disordering reactions. In the temperature range of 850-960°C, the SIMS measured Ga self-diffusivity values showed an activation enthalpy of 4 eV, and are larger than previously compiled Ga self-diffusivity and Al-Ga interdiffusivity values obtained under thermal equilibrium and intrinsic conditions, which are characterized by a 6 eV activation enthalpy. SIMS, CV, and TEM characterizations showed that the as-grown superlattice layers were intrinsic which became p-type with hole concentrations up to ~2×10¹⁷ cm^-3 after annealing, because the layers contain carbon. Dislocations of a density of ~10⁶-10⁷ cm^-2 were also present. However, the factor responsible for the presently observed larger Ga self-diffusivity values appears to be Si outdiffusion from the substrate, which was determined using CV measurements. Outdiffusion of Si decreases the n value in the substrate which causes the release of excess Ga vacancies into the superlattice layers where the supersaturated Ga vacancies enhance Ga self-diffusion

   Keywords:
   annealing;carrier density;chemical interdiffusion;diffusion in solids;dislocation density;enthalpy;gallium arsenide;III-V semiconductors;secondary ion mass spectra;semiconductor superlattices;silicon;surface diffusion;transmission electron microscope examination of materials;vacancies (crystal);