Organometallic chemical vapor deposition of ZnO on sapphire, using the reaction of diethylzinc with H20/H2, N20/N2, and CO2/H2 oxidizing gas systems, has been studied. Epitaxial films have been achieved at temperatures of 400 ~ and 730~ respectively, in the first two systems. The films have been characterized using scanning electron microscopy (SEM), reflection electron diffraction (RED), and surface acoustic wave techniques.* Electrochemical Society Active Member.

The potential difference between grain boundary and bulk and the concentrations of native and foreign point defects in the bulk, the grain boundary (gb), and the subgrain boundary space‐charge region (sg) of polycrystalline Al2O3 doped with acceptors are computed for the case that the dopants segregate at the grain boundaries, with either the ionized or the nonionized acceptor as the dominant species. Expressions are derived for the effective dc conductivity of a polycrystalline material on the basis of a model in which the grain has one or two shells with conductivities different from that of the bulk. Combination of the two results yields expressions for the effective ionic and electronic conductivity of doped A12O3 as a function of grain size with distribution coefficients gb/sg, mobility ratios in the various regions, and equilibrium constants as parameters. At impurity concentrations normally found in ceramics, the contribution by subgrain boundaries to conductivity may be neglected. The theoretical results are compared to published data for Al2O3:Mg, Fe, and Ti.

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This paper describes the regrowth and activation characteristics of Si-implanted GaAs resulting from rapid thermal annealing (RTA) using optical radiation heating. Activation of Si in GaAs by RTA is observed to increase with temperature up to a maximum value, then decrease sharply for additional increases in temperature. The optimum annealing temperature is dependent on both implant dose and annealing time. This activation behavior in RTA time regimes is explained by the competition between kinetic and thermodynamic factors. From Arrhenius plots of the activation data, regrowth under these conditions is shown to be a thermally activated process. Electrical and photoluminescence measurements demonstrate that Si self-compensation limits activation at high annealing temperatures.Ion implantation has become the most viable method available for controllably and reproducibly introducing shallow conductive layers into GaAs for application to digital and monolithic microwave integrated circuit fabrication. A requisite step in ion implantation processing is a high temperature anneal to reduce the ion damage produced in the crystal during implantation and to activate the implanted dopant. Furnace annealing at about 850~ for 15-20 rain with the use of arsenic overpressure or encapsulating layers is normally employed for activating implants. Rapid thermal annealing (RTA) has been shown to yield higher peak carrier concentrations and sharper dopant profiles than furnace annealing (1). More importantly, RTA has greater application for annealing selfaligned n + implants in MESFET and HEMT devices and for implanted contact layer activation in other structures where long duration furnace anneals can cause degradation. Silicon has been studied here, as it is the most commonly employed n-type species for GaAs implantation. Because of the amphoteric nature of Si in GaAs, its activation behavior can be strongly dependent on the parameters of the annealing process. In this work, the regrowth and activation characteristics of Si-implanted GaAs and the carrier loss due to self-compensation under RTA conditions are studied and discussed.

A chemical vapor deposition system for the growth of epitaxial (112̄0) ZnO films on (011̄2) sapphire, employing the reaction of zinc vapor and carbon dioxide, was investigated. Growth rates as high as 30 μm/h at a substrate temperature of 700-750 °C were achieved. Films grown on substrates with thin presputtered layers exhibited smooth surfaces and improved crystal perfection as determined by SEM, reflection electron diffraction, and acoustic evaluation. Films had high resistivity which eventually degraded on exposure to atmosphere. Surface acoustic wave interdigital transducers were fabricated on lithium-diffused films, and the electromechanical coupling coefficient of 1.39% was measured for a film thickness to wavelength ratio of 0.13.