Composition inhomogeneity and structural defects in Czochralski grown Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript> solid solution crystals

The relationship between the plastic strain and the inhomogeneity of germanium distribution in single crystals of Ge _x Si_{1 ? x} (x = 4–9 at %) solid solutions grown using the Czochralski method has been studied. It is established that plastic straining develops via the nucleation of dislocations at their sources occurring in the Ge segregation bands, while the inhomogeneous profile of Ge distribution across the growth direction is caused by thermoelastic stresses.     

Growth and properties of single crystals of Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> (0 < <Emphasis Type="Italic">x</Emphasis> < 0.35) solid solutions

Single-crystalline Si_{1 − x} Ge _x ingots with a germanium content of up to 35 at. %, a diameter of 10mm, and a length of up to 10 cm were grown using the crucibleless float-zone melting technique. The ingots had a homogeneous distribution of germanium and a low density of dislocations. The material was characterized with respect to the structure and electrical properties. The resistivity and the carrier lifetime, mobility, and concentration in Si_{1 − x} Ge _x single crystals have been studied as functions of the germanium content.     

Properties of amorphous Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>:H (<Emphasis Type="Italic">x</Emphasis> = 0−1) films

Plasma deposition has been used to grow Si_1?x Ge _x :H(x= 0 ? 1) films, undoped and doped with PH₃ or B₂H₆, for p-i-n solar cells and other optoelectronic applications. The optical, electrical, and photoelectric properties of the films have been studied at constant hydrogenation and doping levels. The films deposited under appropriate conditions are amorphous, and three-layer solar cells fabricated from such films offer an efficiency of 9.5% at an illumination of 100 mW/cm². The photoresponse of the a-Si_{1 ? x} Ge _x :H films strongly depends on Ge content. The hydrogen concentration in the films was controlled by varying the gas phase composition and was determined from the IR absorption in the films.     

Carrier mobility in Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> crystals

We have studied the 300-K carrier mobility in Czochralski-grown single crystals of undoped and heavily boron doped Si_{1 ? x} Ge _x (0 < x < 0.02) alloys. Comparison of our experimental data with theoretical predictions indicates that the Ge atoms in dilute Si_{1 ? x} Ge _x alloys do not act as neutral scattering centers. The carrier mobility related to the scattering by Ge atoms is governed by disorder (alloy) scattering. The carrier mobility in the boron-doped Si_{1 ? x} Ge _x alloys is much lower than that in the undoped alloys, depends very little on Ge content, and is governed by ionized impurity scattering.     

Cluster diagnostics in Si<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions using low-energy ion backscattering spectroscopy

The fraction of germanium clusters in solid solutions of the Si_1?x Ge _x system with a small germanium content (x ～ 5%) was determined using a method based on the energy analysis of argon ions scattered, upon single and double collisions in the sample, at an angle of θ = 129° relative to the primary beam of ions with an energy of several kiloelectronvolts. Using the proposed low-energy ion backscattering spectroscopy (LEIBS) technique, it was found that the fraction of germanium clusters in the samples studied was ≤20%. The LEIBS method provides a several-fold decrease in the detection threshold for a cluster component in the semiconductor compound as compared to the traditional method based on the measurements of ion scattering at small angles.     

Properties of YBaCuFe<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ni<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>5</Subscript> (0 < <Emphasis Type="Italic">x</Emphasis> ≤ 0.3) solid solutions

YBaCuFe_{1 – x}Ni_xO₅ solid solutions are shown to exist for x 0.3. Data are presented on the lattice parameters, thermal stability, thermal expansion, electrical conductivity, thermoelectric power, magnetic susceptibility, and dielectric properties of the solid solutions. Ni substitution for Fe notably increases the electrical conductivity of the solid solutions, reduces their thermoelectric power and thermal expansion, and shifts the antiferromagnetic—paramagnetic phase transition and dielectric anomalies in YBaCuFe_{1 – x}Ni_xO₅ to lower temperatures.Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1515–1519.Original Russian Text Copyright © 2004 by Chizhova, Klyndyuk, Bashkirov, Petrov, Makhnach.     

Thermal conductivity of Er<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Sn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Se (<Emphasis Type="Italic">x</Emphasis> ≤ 0.025) solid solutions

The thermal conductivity of Er _x Sn_{1 ? x} Se solid solutions has been measured at temperatures from 80 to 360 K. The results have been used to evaluate the electronic and lattice components of thermal conductivity for elastic carrier scattering, parabolic bands, and arbitrary degeneracy. With increasing erbium content and temperature, both the electronic and lattice components decrease considerably. Long-term annealing increases both components. It follows from the present experimental data that heat conduction in Er _x Sn_{1 ? x} Se is mainly due to phonons and that the observed rise in thermal resistance with Er content is due to phonon-phonon and paramagnetic-ion scattering.     

Segregation of aluminum and indium impurities in Ge<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> crystals

Crystals of aluminum-and indium-doped Ge_1?x Si _x (0<x≤0.25) solid solutions with a silicon concentration increasing linearly along the growth direction have been grown by a modified Bridgman method with the use of germanium seeds and continuous feeding of the melt with silicon. Using the Pfann approximation and virtual crystal model for solid solutions, we have evaluated the impurity distribution in melt-grown binary crystals with a linear axial composition profile. The aluminum and indium concentration profiles extracted from Hall effect measurements indicate that the segregation coefficients of these impurities in Ge_1?x Si _x crystals are linear functions of the solid-solution composition.     

Relaxation phenomena in EDAMn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Cl<Subscript>4</Subscript> perovskite; 0≤ <Emphasis Type="Italic">x</Emphasis> ≤ 1 perovskite

The electrical properties measurements were carried out for the complex (CH₂)₂Mn_1–xCd_xCl₄, 0.0 x 1.0 at different temperatures as a function of frequency (100–1000 kHz). Four transition points were obtained for x = 0.5, which were assigned as thermochroism, interlayer exchange interaction, order-disorder and chain melting transition. The presence of more than one straight line in the conductivity data clarifies the presence of more than one conduction mechanism, and the calculated values of the activation energy indicate the semiconducting characteristics of the investigated complexes. The values of the relaxation time depend on Cd-content as well as the heating temperature. The expected critical concentration at x = 0.5 agrees well with the percolation theory of Mont-Carlo group. The IR spectra indicate that, the force constant of the bonds and the atomic mass vibration are affected by Cd-content.     

Photoelectric properties of TlIn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Pr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>2</Subscript> (0 ≤ <Emphasis Type="Italic">x</Emphasis> ≤ 0.04) single crystals

TlIn_{1 ? x} Pr _x Se₂ (0 ≤ x ≤ 0.04) single crystals have been grown, and their photoelectric properties have been studied. The results have been used to determine the band gap and photosensitivity range of the crystals.     

Approaches to improving the accuracy in X-ray fluorescence analysis of Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> films

This work examines approaches to improving the accuracy in the X-ray fluorescence determination of the composition and thickness of thin Si_{1 − x} Ge _x films on Polikor alumina substrates. We calculate correction coefficients that take into account the interelement effects in the films and demonstrate the possibility of reaching the required accuracy level in determining film composition and thickness. The results are used to optimize conditions for the preparation of films with tailored electrical properties.     

Effect of high-pressure high-temperature processing on the phase composition of Mn<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>Cr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Sb (0 ≤ <Emphasis Type="Italic">x</Emphasis> ≤ 1) alloys

High-pressure high-temperature processing (p = 7 GPa, T = 2300 K) has been shown to alter the phase composition of Mn_2?x Cr _x Sb alloys, resulting in a two-phase state: Mn₃Sb (sp. gr. Pm3m, no. 221) and a hexagonal phase of variable composition (sp. gr. P6₃/mmc, no. 194). With increasing chromium concentration, the content of the hexagonal phase increases, while that of the cubic phase drops. In addition, the occupancy of the bipyramidal interstitial sites in the hexagonal phase increases, reaching a maximum in the single-phase alloy MnCrSb (Ni₂In structure).     

Mechanism of AC charge transport in TlSb<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ga<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>S<Subscript>2</Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0 and 0.03)

The dielectric properties and ac electrical conductivity of TlSb_1–xGa _x S₂ (x = 0, 0.03) single-crystals have been measured in the frequency range 5 × 10⁴ to 3.5 × 10⁷ Hz. Experimental data on the frequency dispersion of the dielectric coefficients and electrical conductivity of the TlSb_1–xGa _x S₂ (x = 0, 0.03) single crystals have allowed us to identify the nature of the dielectric loss and the mechanism of charge transport and evaluate parameters of localized states in the band gap. The incorporation of gallium atoms into the crystal lattice of TlSbS₂ crystals has been shown to lead to an increase in the Fermi-level density of states and mean hop time and distance.     

Crystal Structure of Nb<Subscript>5</Subscript>Si<Subscript>3 − <Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript>0.5 + <Emphasis Type="Italic">x</Emphasis></Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0–0.5)

The structure of the ternary compound Nb₅Si_{3 ? x}P_{0.5 + x} (x = 0–0.5) is determined by single-crystal x-ray diffraction: sp. gr. P6₃mc, a = 1.32350(5) nm, c = 0.52954(1) nm; R _F = 0.028, R_w = 0.081 for 547 reflections with F _hkl > 4.0σ(F _hkl ). Relations between the structure of Nb₅Si_{3 ? x}P_{5 + x}, the Mn₅Si₃ structure type, and its derivatives are discussed.     

Reverse recovery of Si/Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> heterodiodes fabricated by direct bonding

We have studied the process of reverse recovery of Si/Si_{1 − x} Ge _x heterodiodes fabricated by direct bonding of (111)-oriented n-type single crystal silicon wafers with p-type Si_{1 − x} Ge _x wafers of the same orientation containing 4–8 at. % Ge. An increase in the germanium concentration N _Ge in p-Si_{1 − x} Ge _x layer is accompanied by a decrease in the reverse recovery time of heterodiodes. The presence of a sharp drop in the reverse current on the diode recovery characteristic can be explained by the existence of a narrow region with decreased minority carrier lifetime at the bonding interface (compared to carrier lifetime in the bulk), which is caused by the accumulation of misfit dislocations (generated by bonding (in this region). The results demonstrate the principal possibility of creating fast-recovery diodes based on the Si/Si_{1 − x} Ge _x heterosystem for high-power semiconductor devices manufactured using the direct bonding technology.     

Hydrochemical synthesis of AgCl<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Br<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript> solid solutions

A phase-component model is proposed for the hydrochemical conversion of silver chloride to AgCl _x Br_{1 − x} solid solutions, and the corresponding quantitative relations are derived. Experimental data are used to obtain a relation between the equilibrium composition of solid solutions and that of the liquid phase at different temperatures. The possible mechanisms of solid-solution formation are considered.     

Anomalous Hall effect in Co<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> granular films deposited by magnetron co-sputtering

In this research, Co _x Si_1?x granular films with Co volume fraction (x) varying from 0.36 to 1 were prepared by using a magnetron co-sputtering method. The influence of x on the temperature-dependent longitudinal resistivity (\({\rho _{xx}}\)) and anomalous Hall effect (AHE) in Co _x Si_1?x granular films were systematically studied. The dependence of \({\rho _{xx}}\) on measuring temperature could be explained by the superposition of fluctuation-induced tunneling (FIT) process and temperature-dependent scattering. Interestingly, the contribution from scattering and FIT can be distinguished. The saturated Hall resistivity (\(\rho _{{xy}}^{A}\)) increased monotonically with decreasing x. In addition, the \(\rho _{{xy}}^{A}\) amplified nearly 26-fold as x decreased from 1 to 0.4. For the pure Co film (x?=?1), the intrinsic and side jump mechanisms dominated the Hall transport. However, the deviation of classical scaling relation was observed in other samples, which was mainly ascribed to the influence of interfacial scattering.     

Homogeneity of high-resistivity <Emphasis Type="Italic">p</Emphasis>-Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>〈Au〉 crystals

p-Si_{1 ? x} Ge _x crystals have been diffusion-doped with gold. Gold diffusion in the p-Si_{1 ? x} Ge _x 〈Au〉 samples and their electrical properties have been studied. The results demonstrate that the highest gold concentration in the crystals can be achieved in the temperature range 1000–1050°C. An expression has been derived which indicates that, all other factors being the same, compensation with Au, an amphoteric impurity, insures better homogeneity compared to codoping with acceptor and donor impurities. The hole concentration homogeneity in gold-compensated samples is at the same level as or even better than that in the uncompensated material.     

Boron doping of Si<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>/Si heterostructures grown by silicon sublimation in germane medium

Controlled boron doping of Si_{1 − x} Ge _x epilayers has been achieved during low-temperature growth of SiGe/Si(100) heterostructures by sublimation of boron-doped silicon in a germane medium. Boron-doped single-crystalline silicon plate was sublimed by resistive heating to ∼1300°C. Using this source, heterostructures with selectively doped layers, sharp dopant concentration profiles, and a maximum boron concentration of ∼1 × 10¹⁹ cm⁻³ were obtained.     

Structural and magnetic properties of Cr<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>V<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Te (<Emphasis Type="Italic">x</Emphasis> = 0−0.4) solid solutions

Cr_1?x V _x Te solid solutions with a hexagonal structure (NiAs type) have been obtained in the composition range x = 0?0.4 by direct melting of elemental mixtures, followed by annealing and quenching. The 80-K magnetic moment is found to decrease from 2.4μ_B in CrTe to 1.52μ_B in Cr_0.6V_0.4Te. The Curie temperature varies from 342 K to 321 K, respectively.