Search

Ion milling rates of III-V nitrides have been measured as a function of Ar(+) ion beam. Ion channeling, AES and SEM enable the analysis of the influence of nitride surfaces. Ion milling rates for these samples are smaller than those of GaAs and InP. Ion milling has no influence on the surface morphology of the nitride. All these nitrides exhibit more back-scattering for Ar(+) energies up to 500 eV.

Uncrystallized indium-gallium-zinc-oxide (InGaZnO) thin-film transistors (TFTs) combined with an aluminum nitride (AlN) dielectric have been used to promote performance and steadiness. However, the high deposition temperature of AlN films limits their application in InGaZnO flexible TFTs. In this work, AlN layers were deposited via low-temperature plasma-enhanced atomic layer deposition (PEALD), and InGaZnO films were fabricated via high-power impulse magnetron sputtering (HIPIMS). The band alignment of the AlN/InGaZnO heterojunction was studied using the X-ray photoemission spectrum and ultraviolet visible transmittance spectrum. It was found that the AlN/InGaZnO system exhibited a staggered band alignment with a valence band offset ΔEv of −1.25 ± 0.05 eV and a conduction band offset ΔEc of 4.01 ± 0.05 eV. The results imply that PEALD AlN could be more useful for surface passivation than a gate dielectric to promote InGaZnO device reliability under atmospheric exposure. [ABSTRACT FROM AUTHOR]

Implant isolation schemes, specifically used for dense and greatly doped III-V devices such as quantum well lasers and heterojunction bipolar transistors (HBT) generate extended defects, situated particularly at areas of strain. Diffusion of keV H+, MeV O+ and F+ ions is analyzed. MeV O+ ions are used for isolating strained quantum well lasers which work at 0.98 micrometers and keV H+ and F+ ions are used for isolating GaAs/AlGaAs HBTs.

Si+ and Be+ ions, implanted into InGaAsP grown lattice, matched to InP by molecular beam epitaxy, are experimented upon to determine the electrical activation characteristics as a function of ion dose, annealing time and annealing temperature. For both Si and Be ions, maximum doping concentrations were obtained with the electrical activation energies of 0.58 and 0.39 electron volts. High resistance layers for isolation is produced by multiple energy implant of F or H ions. The maximum sheet resistance for the InGAsP is determined for F implants by annealing at 450 degrees centigrade. Electron cyclotron resonance CH4/H2/Ar discharges at low direct (dc) basis is used in the determination of the smooth, anisotropic dry etching of the InGaASp.

The use of tantalum nitride thin films grown by reactive sputtering on diamond substrates as microelectronic resistors was investigated. The results showed that the thin films had excellent morphological properties and had excellent stability even at temperatures as high as 400 degrees celsius. Film resistance was stabilized by post-deposition sintering. This indicated that the material can be used as masks for self-aligned dry etching of the diamond.

The passivation of carbon-doped GaAs epilayers grown by molecular beam epitaxy and metalorganic vapor phase epitaxy was investigated using infrared absorption, secondary ion mass spectrometry and Hall measurements. The results showed that H2 in the growth and annealing ambients were very effective in the passivation of carbon. Annealing treatment at temperatures above 550 degrees celsius was able to activate carbon acceptors that were passivated by hydrogen.

Research was conducted on the effects of hydrogen plasma treatment and proton implantation on the electrical properties of AlGaAsSb layers. Results showed that hydrogen sourced from plasma is capable of producing electrically neutral complexes withdonors and acceptors in the AlGAAsSb material system. The system was also foundto transform into a p type upon heavy irradiation of AlGaAsSb protons.

The outcome of hydrogen passivation studies and the effect of proton implantation on InAs semiconductors is discussed. Hydrogen and deuterium plasma treatment were conducted on p-type InAs samples. Current-voltage characteristics at 77-300 K were measured in the preparation of the structures. An n-type layer at the surface of p-InAs was produced by the plasma and implantation treatments.

The use of tri-isobutylgallium (TIBG) and tri-isopropylgallium (TIPG) for enhancing the metalorganic molecular beam epitaxial growth of InGaP was investigated. The result showed that the incorporation rate of carbon decreased as the temperature increased. The measured lattice constant varied linearly with the flow. The band gap varied discontinuously with the lattice constant.

A study was conducted on the effectivity of using mega electronvolt (MeV) O+ ion implantation for isolation of GaAs/AlGaAs heterojunction bipolar transistors (HBTs). High sheet resistances were observed in the GaAs epitaxial layers. The presence of a residual conductivity was attributed to hopping processes with small activation energies. The study shows that MeV can effectively produce HBTs with optimal direct current properties. MeV application also proved to be clear due to the thick layer stuctures involved.

A study was conducted on the electrical properties of Schottky diodes produced by various metals with n- and p-type layers of AlGaAsSb and the effects of (Nh4)2S and hydrogen plasma treatments on these properties. Results showed that in AlGaAsSb the Fermi level at the surface is pinned closely to the valence-band edge. The deposition of Sb was also observed to have shifted the Fermi level close to mid gap. The study showed that hydrogen passivation of the native acceptors in AlGaAsSb coincides with an upward shift of the material's surface Fermi-level position.

A study on the formation of high-resistivity layers in initially high-doped n- and p-type epitaxial galliumarsenide show that the projected ranges of these ions are 14.0 and 28.8 micrometers at 25 and 50 MeV respectively. Sheet resistance of thin epitaxial surface layers exposed to these ions increases rapidly with fluence in the range of 10 raised to the 13th power to 10 raised to the 15th power centimeters (super -2). The values may decrease depending on initial doping density.

High quality Pnp heterojunction bipolar transistors can be obtained through the use of carbon: aluminum gallium arsenic and tin doping from tetraethylin during metalorganic molecular beam epitaxy growth. Large area devices with gains of 45 at a base doping level of 1.5 x 10 (super 9) cm (super -3) were demonstrated. The slight doping levels were obtained with carbon and tin reducing the parasitic resistances in the transistor.

A combination of ammonia gas, and titanium tetrakis liquid precursors were used to analyze the process kinetics, chemical composition, morphology, microstructures of rapid-thermal low pressure metalorganic chemical vapor deposited titanium nitride films. The results showed that carbon and oxygen impurity levels were as low as five percent, with some degree of epitaxial relation to the substrate.

A single-energy, MeV implant isolation method for thick II-V semiconductor device structures is presented. The process greatly simplifies conventional keV implant isolation, which uses ten separate ion energies in isolating HBT structures. Damage profile is constant over the primary part of the ions range. The damage usually found with the MeV ions end of range can be kept secure in the underlying substrate.

The implant activation efficiency of silicon (Si) and beryllium (Be) ions in undoped epitaxial layers of indium aluminum arsenate (InAlAs) and indium gallium arsenate (InGaAs) were measured in a study using organometallic vapor phase epitaxy. Compared to InAlAs, InGaAs obtained dopants with higher activation efficiencies. Low activation was observed in low dose Be implants due to lack of sites. Higher sheet carrier densities were obtained via Si in InAlAs and for both Si and Be saturations exist in the carrier density with increasing annealing temperature.