Anomalous tensoelectric effects in gallium arsenide tunnel diodes

Anomalous tensoelectric phenomena induced in a tunnel p-n junction by a concentrated load and by hydrostatic compression were studied. The anomalous tensoelectric effects are caused by the action of concentrators of mechanical stresses in the vicinity of the p-n junction, giving rise to local microplastic strain. Under the conditions of hydrostatic compression prolate inclusions 100–200 å long play the role of concentrators. Analysis of irreversible changes in the current-voltage characteristics of tunnel p-n junctions made it possible to separate the energy levels of the defects produced with plastic strain of gallium arsenide.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 84–88, August, 1987.     

Appearance of flaws in layers of AlxGa1−xSb solid solutions during epitaxial growth from the liquid phase

Layers of Al_xGa_1–xSb (x0.7) solid solutions were grown epitaxially from the liquid phase on substrates of gallium antimonide. Aluminum was added to the melt during the buildup of an epitaxial layer. In these layers were found inclusions of the solvent as well as regions of localized chemical inhomogeneities. It is shown here that the appearance of such flaws is intimately related to the relief which the GaSb substrate has formed by the time aluminum enters into the solution. A mechanism of this flaw formation is suggested.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 75–80, June, 1976.     

Electrical and luminescent properties of gallium phosphide with radiation defects

The energy spectrum of local levels and the effect of radiation damage on intensity and character of cathode luminescence lines in the visible region of the spectrum in gallium phosphide single crystals prepared from a solution-melt by the Chochralski method are examined. It is shown that as a result of irradiation by fast electrons with E_e=1 Mev and Co 60 -quanta, both donor and acceptor centers are introduced into the original crystals. New radiation centers producing lines in the spectral range studied (500–600 nm) were not observed after irradiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 49–54, June, 1976.     

Forbidden band width and optical properties of thin gallium phosphide films

The temperature dependence of the forbidden band width of gallium phosphide films deposited by a discrete method on various substrates has been investigated in the present work. The influence of the material and temperature of the substrate on the forbidden band width and its change with thickness, are determined. This latter is treated as the appearance of a quantum dimensional effect. The dispersion of gallium phosphide films is measured in the visible band of the spectrum.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 9, pp. 88–92, September, 1971.     

Electrical and optical properties of gallium phosphide films

The electrical and optical properties of gallium phosphide films, prepared by the explosive evaporation and three-temperature methods, are studied. It is shown that film properties are strongly dependent on method of preparation and substrate temperature. Gallium phosphide films prepared by explosive evaporation having perfect structure possess the best electrical and optical properties.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 6, pp. 54–58, June, 1971.     

Structure and properties of interphase boundaries of gallium arsenide-metal (dielectric)

To study the nature and properties of potential barriers in gallium arsenide devices, we have investigated structural phase transitions in GaAs contacts with multilayer films containing refractory transition-metal borides (TiB₂, LaB₆). We verified the important role in degrading Schottky barrier device performance played by local mechanical stresses introduced at the interface by lateral nonuniformities in interphase interactions. We examine the electrical properties of MIS gallium arsenide devices, taking into account the high density of electronic surface states (ESS). We show it is possible to control the density of ESS by selecting the dielectric, and we discuss its deposition and annealing with a pulsed laser. We discuss the nature of potential barriers in gallium arsenide devices, drawing upon our data and previously published data and modern theoretical models.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 10, pp. 52–62, October, 1993.     

Electroluminescence of gallium phosphide in the visible spectrum region

The effect of doping impurities and the container material on the color and intensity of electroluminescence (EL) of gallium phosphide crystals grown from the melt in gallium is considered. It is found that the maximum efficiency of red EL is observed in crystals grown in quartz containers, and of green EL — in crystals produced in alundum containers having aluminum nitride coatings. The optimal doping-impurity concentrations are determined for producing diodes with red, yellow, and green radiation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 12–16, April, 1973.     

The effect of carrier concentration in the semiconductor on the voltage-current characteristics of Schottky barrier diodes at low temperatures

We report the results of a study of voltage-current characteristics of gallium arsenide metal-semiconductor Schottky barrier structures, in which palladium and W-Ni alloy were electrochemically deposited in SiO₂ windows to form the barrier. It is demonstrated that the voltage-current characteristics are significantly distorted at low temperatures. The observed behavior of the voltage-current characteristics at low temperatures —the appearance of excess current and the increase in the ideality factor with carrier concentration in the excess current regime —is explained by a model in which peripheral mechanical stresses in the contacts lower the potential barrier height on the periphery of the contacts.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No, 10, pp. 87–93, October, 1986.     

Microwave–assisted synthesis of <Emphasis Type="Italic">submicrometer</Emphasis> GaO(OH) and Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> rods

Submicrometer sized gallium oxide hydroxide (GaO(OH)) and gallium oxide (Ga₂O₃) rods have been successfully fabricated on a large scale by refluxing an aqueous solution of Ga(NO₃)₃ and NH₄OH in a simple domestic microwave oven (DMO). The structures, morphologies, compositions and physical properties of the as–synthesized and calcined products have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), selected area energy dispersive X-ray spectroscopy (SAEDS), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), and energy dispersive X-ray (EDX) analysis. TEM images show that submicrometer sized as–synthesized Ga O(OH) rods have diameters of 0.3–0.5 m and lengths of 3.2–3.5 m. The calcined product consists of submicrometer rods with diameters of 0.4–0.5 m and lengths of 5–5.5 m. XRD, EDX and SAED analysis together indicate that the as–synthesized product has an orthorhombic gallium oxide hydroxide (GaO(OH)) crystal structure, and that the calcined product is rhombohedral Ga₂O₃. A possible mechanism for the formation of submicrometer sized GaO(OH) rods is discussed briefly.     

Some photoelectric and electrical properties of copper-doped gallium arsenide

A study has been made of the conditions for the formation of impurity centers having an ionization energy E _v + 0.1 eV in copper-doped gallium arsenide. Photoconductivity is demonstrated at 10.6 . The results of the photoconductivity study are used to calculate the absorption coefficient and cross section for photon capture by these impurity centers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 40–44, September, 1970.The authors thank V. N. Detinko, A. S. Petrov, and A. P. Vyatkin for constant interest in this study.     

Temperature dependences of the flow and critical shear stresses of dispersion-hardening alloys

A study was made of the temperature dependences of the flow stress _0.1 (T) and of the critical shear stress _cr(T) of Cu-15% A1-(1–2)% Co, Cu-8% A1-(2–2.8)% Co, and Cu-4% A1–2% Co alloys containing noncoherent intermetallic particles. In the case of single crystals at temperatures 77–673° K there was a good agreement between the theoretically calculated values of the Orowan hardening and those found experimentally, so that the dependence _cr(T) was governed by the temperature dependence of the shear modulus G(T). For polycrystalline samples the usual dependence of the mechanical propertiesties on the grain size was not observed. At temperatures from 77 to 473–573°K the dependence _0.1 (T) was similar to the dependence G(T) and a good agreement was observed between the theoretically calculated dispersion hardening effects with those found experimentally. At temperatures T > 473–573°K the deformation was influenced greatly by grain-boundary glide, which enhanced the dependence _0.1 (T) compared with that expected theoretically.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 85–91, June, 1980.     

Low-temperature internal friction of modified Ti50Ni42Co8 alloy

In this work we have investigated the internal friction of the alloy Ti₅₀Ni₄₂Co₈ with Hf (0.5–0.8 at. %) and Y (0.1 at. %) additives in the temperature range 4.2–293 K at frequencies of 200–600 Hz. We see two peaks on the temperature dependence of the internal friction for the alloy oxidized in an air atmosphere at 1100 K: the first peak at T=40 K is connected with movement of interphase boundaries during the thermoelastic phase transformation occurring according to the scheme B2 R B19'; and the second peak at 220–240 K is mainly connected with diffusion under the pressure of hydrogen adsorbed on the oxide particles. The hydrogen penetrates the alloy during sample preparation upon etching and electropolishing in acid solution. Support for the latter hypothesis comes from internal friction vs temperature data for the alloy hydrogen-charged at 1073 K in a gaseous atmosphere and then subjected to vacuum annealing at the same temperature, as well as the results of x-ray diffraction analysis.Voronezh Polytechnical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 14–20, December, 1992.     

Measurement of specific transient resistances of ohmic contacts to thin semiconductor layers

A method is described for measuring specific transient resistances of ohmic contacts to thin semiconductor layers by experimentally taking into account the spreading resistance. Studies are performed by this method on the way in which the specific transient resistances of AuGe-Ni and Au-Ni contacts to n-type gallium phosphide depend on the brazing temperature.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 80–83, June, 1976.     

Anomalous polarization dependence of the photon drag and optical rectification fields inn-type gallium phosphide

The photon drag and optical rectification response fromn-type gallium phosphide containing 2.4×10¹⁶ electrons cm^–3 has been studied using laser sources at 10.61 and 2.83m. By using different contact configurations, the existence of an additional electric field term in the propagation direction has been deduced. This field is shown to arise from the spatial derivatives of the photon drag and optical rectification field components caused by absorption of the radiation. The importance of this effect in detector design is considered.     

Behavior of copper in gallium arsenide with a high tellurium concentration

The electrophysical properties and cathode luminescence spectra of gallium arsenide with a high tellurium concentration (n = 2·10¹⁸ cm^–3) alloyed with copper are investigated under different diffusion conditions. Centers are determined from measurements of the Hall effect with an ionization energy of 0.190 ± 0.006 eV whose concentration does not depend on the arsenic vapor pressure (0.1 and 1 atm) and the cooling rate of the samples from the diffusion temperature. A band with h_m = 1.30–1.32 eV whose intensity depends on the cooling conditions of the samples was observed in the cathode luminescence spectra of these samples. The nature of the observed defects is discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 93–99, July, 1979.In conclusion of this article the authors express their gratitude to L. K. Tarasova for preparation of the samples.     

Influence of the temperature and structural state on the systematic features of plastic deformation in Mo-Re-based alloys

The salient aspects of the formation of a dislocation structure during plastic deformation of the alloys Mo-47 wt. % Re and Mo-47 wt. % Re-1 vol. % ZrO₂ at T=300 K in previously recrystallized and polygonalized structural states have been studied with an electron microscope. The studies revealed the systematic features of rotational modes of plastic deformation in these alloys under conditions of substructural hardening and high-temperature grain-boundary slip. An analysis is made of the effect that the substructure and highly dispersed particles of the oxide phase have on the plastic deformation and mechanical properties of Mo-Re-based alloys at T=300-1500 K.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 96–104, December, 1994.     

Efficiency of the formation of radiation defects in heat-treated dislocation-free zone n-silicon

A study was made of processes involved in the formation of radiation defects (RD) in n-type dislocation-free silicon subjected to high-temperature heat treatment at T_t = 600–1300°C. It was established that the effectiveness of introducing compensating RDs changes significantly with an increase in T_t. It is proposed that interstitital inclusions present in the crystal are transformed during heat treatment, these inclusions creating strain fields around themselves and thus influencing the efficiency with which radiation defects are formed.A. N. Sevchenko Scientific Research Institute of Applied Physical Problems. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 93–95, November, 1993.     

Epitaxy of AlxGa1−xSb films from a molten metal.

Conclusions Crystallization from a solution of antimony in a gallium-aluminum melt has been used to produce epitaxial Al_xGa_1–xSb films with x=0 to 0.4; isothermal (T = 450, 500, 550°C) and isoconcentration (0; 1; 2.4 at. % Al) sections have been drawn for the liquidus surface on the composition plane. X-ray microspectral analysis has been used to examine the composition of the Al_xGa_1–xSb films in relation to aluminum content in the melt, as well as the distribution of Al and Ga over the epitaxial film. These films had a perfect structure. The results enable one to determine the solution composition needed to grow Al_xGa_1–xSb epitaxial films at 450–550°C on gallium antimonide substrates, and it is shown to be possible to make heterostructures in the Al_xGa_1–xSb-GaSb system.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 9, pp. 146–148, September.We are indebted to Zh. I. Alferov and V. I. Shveikin for attention and support in this work.     

Mechanism and kinetics of the mass transfer of impurities in polar A3B5 compounds

The effect of the electric current and the crystallographic orientation of the samples on the rate of displacement of molten inclusions in gallium arsenide is examined in detail. It is shown that the melting of these inclusions is associated with thermoelectric effects developing at the interphase boundaries between the inclusions and the matrix, and also with the electric transport of the impurities in the molten drop.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 40–46, May, 1976.     

Large-scale crystalline GaN nanowires synthesized through a chemical vapor deposition method

Large-scale, high-density gallium nitride nanowires were successfully synthesized by the direct reaction of gallium and ammonia using gold as initiator. The as-synthesized product was characterized by XRD, SEM, TEM, SAED, and EDS. The results showed that the product is hexagonal wurtzite GaN with high purity. The nanowires have diameters in the range of 60–100 nm and are a few tens of micrometers in length. A remarkable feature is that catalyst particles were observed at the ends of the nanowires, indicating that the growth process can be controlled by the vapor–liquid–solid mechanism. The present results revealed that gold is an effective and advantageous catalyst for the growth of GaN nanowires. PACS 81.05.Ea; 81.10.Bk; 68.65.-k