Showing papers by "Shuit-Tong Lee published in 1992"
TL;DR: In this paper, the authors used secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) to study self-diffusion in GaAs by disordering reactions.
Abstract: Undoped 69GaAs/71GaAs isotope superlattice structures grown by molecular beam epitaxy 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 secondary ion mass spectrometry (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. Characterizations by SIMS, capacitance‐voltage (C‐V), and transmission electron microscopy showed that the as‐grown superlattice layers were intrinsic which turned into p type with hole concentrations of ∼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...
40 citations
TL;DR: Carbon films have been prepared on copper crystals by implantation of carbon at 50-390 keV and at implantation temperatures of 25-100 °C as mentioned in this paper. But no diamond formation was observed.
6 citations
TL;DR: In this paper, the authors measured self-diffusivity values of 69GaAs/71GaAs isotope superlattice structures grown by MBE on n-type GaAs substrates, doped by Si to ~3x1018 cm−3, have been used to study Ga selfdiffusion in GaAs.
Abstract: Undoped 69GaAs/71GaAs isotope superlattice structures grown by MBE on n-type GaAs substrates, doped by Si to ~3x1018 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 AI-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 ~2x1017 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.
TL;DR: In this article, a mass-separated BF 2 + ion beam was used in an ultrahigh vacuum low energy ion beam system for fabrication of shallow junctions, where the temperature of the silicon crystal during bombardment was kept either at room temperature or 500°C.
Abstract: Fluoroboron (BF 2 + ) ion implantation into silicon is frequently used for fabrication of shallow junctions. For scaling down of the junction dimensions, one of the efficient approaches is to lower the implantation energy. This work reports fluoroboron ion interactions with (100) oriented silicon at 10 to 500 eV ion energy. Ion bombardment was carried out using a mass-separated BF 2 + ion beam in an ultrahigh vacuum low energy ion beam system. The temperature of the silicon crystal during bombardment was kept either at room temperature or 500°C. The reactions (both etching and incorporation) were characterized by x-ray photoemission spectroscopy (XPS), Rutherford backscattering (RBS) and Raman scattering. The results show that BF 2 + ions dissociated on the silicon surface at an energy as low as 10 eV and most of fluorine segregated to the surface and desorbed. Both the physical and chemical etching rate of the beam were energy dependent but much lower than the accumulation rate. For beam fluences higher than 1 × 10 18 /cm 2 , continuous amorphous boron films were deposited on silicon.