Outdiffusion through silicon oxide and silicon nitride layers on gallium arsenide
TL;DR: Backscattering of MeV 4He ions has been used to analyze the Ga and As content in SiO2 and Si3N4 dielectric layers deposited on singlecrystal GaAs substrates.
Abstract: Backscattering of MeV 4He ions has been used to analyze the Ga and As content in SiO2 and Si3N4 dielectric layers deposited on single‐crystal GaAs substrates. Changes in impurity concentrations and distributions are seen after isothermal annealing at both 750 and 800°C. Evidence for Ga outdiffusion is clear.
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TL;DR: In this paper, an experimental study of the alloying characteristics of a composite thin-film structure which is often used as an ohmic contact to GaAs is presented, and the specific contact resistance of the Ni/AuGe/GaAs system is measured for a wide range of alloy temperatures and times.
Abstract: An experimental study of the alloying characteristics of a composite thin-film structure which is often used as an ohmic contact to GaAs is presented. A AuGe layer of eutectic composition covered by a thin-film of Ni and deposited on n-type epitaxial GaAs is investigated in order to better understand the relationship between the alloying behavior and the electrical properties of the contact. The barrier energy ϕBn and the specific contact resistance of the Ni/AuGe/GaAs system is measured for a wide range of alloy temperatures and times. The metallurgical properties of the Ni/AuGe/GaAs system are obtained with Auger electron spectroscopy and scanning electron microscopy. Auger spectroscopy combined with in situ sputter etching is used to determine depth-composition profiles for all constituents of both as-deposited and alloyed Ni/AuGe/GaAs contacts. In samples heat-treated below the AuGe eutectic temperature, Ni is found to move rapidly through the intervening AuGe layer to collect at the GaAs interface, and the effective value of ϕBn rises to the value characteristic of Ni/GaAs Schottky diodes. For heat-treatment above the AuGe eutectic temperature, ohmic contact behavior is observed, and uniform alloyed contact surfaces are found to result from the presence of Ni at the GaAs interface. Ga outdiffusion and surface accumulation resulting from GaAs dissociation occurs for all alloy temperatures and times. The Ga outdiffusion appears to be characterized by a very low activation energy.
141 citations
TL;DR: In this paper, the low-temperature properties of the excitationdependent (moving) emissions in Mg, Be-, Cd, and Zn-implanted GaAs layers are investigated with respect to changes in temperature and excitation intensity.
Abstract: The low‐temperature properties of the excitation‐dependent (moving) emissions in Mg‐, Be‐, Cd‐, and Zn‐implanted GaAs layers are investigated with respect to changes in temperature and excitation intensity. The substrates used were epitaxial layers, melt‐grown n‐type crystals, and Cr‐doped semi‐insulating crystals. Donor concentrations of the n‐type substrates were in the range 5×1013 to 2×1018 electrons cm−3. Models explaining a large energy shift are presented for both Cr‐doped and n‐type substrates. The moving emissions are classified into three different cases: (a) donor‐acceptor‐pair emission in relatively pure weakly compensated crystals; (b) donor‐acceptor‐pair emission in impure strongly compensated crystals; and (c) a radiation transition from the conduction‐band tails to the valence band. The donor‐acceptor‐pair emission in the impure compensated crystals shows the shift to lower energy with an increase of temperature in the temperature range 4–50 °K, while the donor‐acceptor‐pair emission in pu...
140 citations
TL;DR: In this paper, the important parameters that affect the electrical characteristics of ion implanted layers in compound semiconductors are discussed and applications of this technology to the fabrication of microwave and electrooptical devices are discussed.
127 citations
TL;DR: In this article, the authors examined the different aspects of ion implantation in semiconductors and found that multivacancies rather than single vacancies are normally produced by ion implantations because of the high flux density and high total dose of the implanted ions.
Abstract: Publisher Summary This chapter examines the different aspects of ion implantation in semiconductors Ion implantation is a superior technique for producing new materials, which are very difficult or impossible to produce by chemical methods Ion implantation is the introduction of foreign atoms or lattice irregularities in the solid An important feature of the introduction of foreign atoms by ion implantation is that this method is applicable to all kinds of materials Depth profiles of the implanted ions can be calculated reasonably well by the Lindhard theory in the case of amorphous material Apart from the bombardment techniques, which can move the atom during the measurement, possible methods for detecting the existence of impurity atoms and their location consist of nuclear magnetic resonance and electron spin resonance measurements It is found that multivacancies rather than single vacancies are normally produced by ion implantation because of the high flux density and high total dose of the implanted ions In the case of single crystals, enhancement of the penetration was observed The radiation enhanced diffusion is assumed to result from the increase of radiation induced vacancies, the occurrence of the secondary channeling and interstitial migration
99 citations
TL;DR: In this paper, the authors used the amphoteric nature of silicon in gallium arsenide (GaAs) to develop diffusion and electrical compensation mechanisms, based on the formation and diffusion of nearest neighbor donor-acceptor pairs.
Abstract: The amphoteric nature of silicon in gallium arsenide is used to develop diffusion and electrical compensation mechanisms. The diffusion mechanism is based on the formation and diffusion of nearest‐neighbor donor‐acceptor pairs. General solutions are presented that predict abrupt diffusion fronts for a wide range of pairing conditions. Experiments support the application of this mechanism to Si diffusion in GaAs at high concentrations. A compensation mechanism for amphoteric dopants is developed as well. The compensation process is driven primarily by the free‐electron concentration. Nearly complete compensation is predicted for large dopant concentrations.
89 citations
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TL;DR: In this paper, mass spectrometric and weight loss measurements of the species effusing from a Knudsen cell containing GaAs were used to obtain vapor pressures over the temperature range 900-1200°K.
350 citations
TL;DR: In this paper, backscattering and channeling effect measurements were used to determine the lattice disorder and distribution, lattice location, and diffusion of species (Rb, Cs, Zn, Cd, Hg, Se, I, and Sb) implanted in Si.
Abstract: Backscattering and channeling‐effect measurements were used to determine the lattice disorder and distribution, lattice location, and diffusion of species (Rb, Cs, Zn, Cd, Hg, Se, I, and Sb) implanted in Si. During anneal sequences we observed (1) enhanced diffusion towards the surface (Sb, Se, and Cd), (2) retardation or precipitation at the surface (Sb, Se, and Cd), and (3) a connection between out‐diffusion and reordering of the amorphous layer (Zn, Cd, Hg, and I). The data also suggest that release of atoms from trapping (precipitation) sites in the implanted layer can be the rate‐limiting process in some cases. These results indicate that out‐diffusion studies such as gas release, may not represent bulk diffusion properties in crystals.
48 citations
TL;DR: In this paper, the diffusion of gallium into silicon through an oxide layer was studied by a p-n junction technique, and the two-boundary diffusion model was estimated to be 5.3 × 10−11 cm 2 sec (√D = 4·4 μ √hr ) at 1100°C and 1.7 × 10 −9 cm 2sec (∆D) = 25.5 μ ∆hr ) in 1250°C.
45 citations
TL;DR: In this paper, a broad-range magnetic spectrograph has been used to study the diffusion of gold into copper in the temperature range 360-500 C by elastic scattering of protons and deuterons.
Abstract: A broad-range magnetic spectrograph has been used to study the diffusion of gold into copper in the temperature range 360-500\ifmmode^\circ\else\textdegree\fi{}C by elastic scattering of protons and deuterons. This is a new technique in solid diffusion measurements and should have fairly wide applicability in intermetallic diffusion. This investigation extends the data a factor of ${10}^{6}$ below the sectioning range. These results together with data of sectioning observers, show the Arrhenius law to be approximately valid over a range in $D$ of 5\ifmmode\times\else\texttimes\fi{}${10}^{8}$. A precise fit to all the data requires a slight upward curvature. In the temperature range studied here, we obtain $Q=45$, 750\ifmmode\pm\else\textpm\fi{}750 cal/mole and ${D}_{0}=0.104\ifmmode\pm\else\textpm\fi{}0.06$ ${\mathrm{cm}}^{2}$/sec. This represents a decrease of about 4000 cal/mole from the most precise data in the sectioning range. This curvature is attributed to diffusion along internal surfaces, although the possibility of multiple diffusion mechanisms still remains.
32 citations
TL;DR: In this paper, the energy spectra of 1 −MeV He+ ions backscattered 150° from a silicon surface have been used to identify and measure the contamination on the surface.
Abstract: Experiments are described in which the energy spectra of 1‐MeV He+ ions backscattered 150° from a silicon surface have been used to identify and measure the contamination on the surface. Contamination from hydrofluoric acid solutions containing gold and copper in concentrations ranging from 0.1 to 100 parts per million was studied. Less than one half a monolayer of contaminant was easily resolved and identified. Coverages of this order were obtained from solutions containing 0.1 ppm of the contaminant.
28 citations