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Highlights: [•] A synthesizing of a new compound LaPdGe3 with the BaNiSn3 type crystal structure. [•] Refinement of the crystal structures of LaPd2Ge and LaPdGe3. [•] LaPd2Ge proved by heat capacity and thermopower to be as a new superconductor. [•] In opposite to LaPdSi3, the lack of superconductivity in its germanide analogue. [•] Large differences in the resistivity and thermopower between both studied germanides. [ABSTRACT FROM AUTHOR]

In this Letter, NiGe/SiO2/n-Ge ohmic contacts were demonstrated with Ge, rather than Ni, diffusion through the ion-implanted SiO2 films to form NiGe. The equivalent Schottky barrier height reduced from 0.58 eV for NiGe/n-Ge to ohmic contact. The anomalous diffusion behavior and accumulation of Ge in the SiO2 near the NiGe/SiO2 interface can be explained by vacancy-enhanced Ge diffusion. It is proposed that the presence of vacancies and Ge atoms embedded in the SiO2 layer play a significant role in the current enhancement by generation of multiple levels in the SiO2 band gap. [ABSTRACT FROM AUTHOR]

Iron–germanium(Fe–Ge) is a complex alloy systemthat includes several structurally and compositionally diverse phasesthat exhibit a range of interesting magnetic properties that can changesignificantly when reduced to nanoscale dimensions. Fe–Ge nanostructureshave been synthesized using chemical and physical deposition methodsbut have not previously been accessible as solution-synthesized colloidalmaterials. Here, we show that colloidal Fe–Ge nanostructurescan be synthesized via the hot injection of an oleylamine solutionof Fe(CO)5into a solution containing GeI4,oleylamine, oleic acid, and hexamethyldisilazane. This approach effectivelymerges recent advances in the synthesis of colloidal Ge nanocrystalswith methods routinely used to synthesize metal and alloy nanoparticles.At 260 °C, spherical nanocrystals of Ni2In-type Fe3Ge2form. Heating the solution at 300 °C transformsthe spherical Fe3Ge2nanocrystals into CoGe-typeFeGe nanowires. The Fe3Ge2nanocrystals areferromagnetic with Tc≈ 265 K,whereas the FeGe nanowires are only weakly magnetic. [ABSTRACT FROM AUTHOR]

The ternary germanides RERh6Ge4 ( RE = Y, La, Pr, Nd, Sm-Lu) were obtained by arc-melting of the elements and subsequent annealing. Single crystals were grown from bismuth fluxes. The samples were studied by X-ray diffraction on powders. The structures of five members were refined from single crystal diffraction data: LiCo6P4 type, P $\bar{6}$ m2, a = 715.8(1), c = 387.33(8) pm, wR = 0.0238, 332 F2 values for LaRh6Ge4, a = 715.0(1), c = 384.96(7) pm, wR = 0.0211, 329 F2 values for PrRh6Ge4, a = 714.28(9), c = 382.57(6) pm, wR = 0.0136, 327 F2 values for SmRh6Ge4, a = 714.2(1), c = 381.6(1), wR = 0.0270, 327 F2 values for GdRh6Ge4, and a = 714.2(2), c = 379.0(1) pm, wR = 0.0273, 324 F2 values for HoRh6Ge4 with 19 variables per refinement. The RERh6Ge4 structures have two crystallographically independent germanium sites in trigonal prismatic coordination, manifesting the close structural relationship with metal-rich phosphides. Together, the rhodium and germanium atoms build up three-dimensional [Rh6Ge4] networks, which leave large channels for the rare earth atoms. Each rare earth atom has coordination number 20 with 12 Rh, 6 Ge, and 2 RE neighbors. Temperature dependent magnetic susceptibility measurements indicate Pauli paramagnetic behavior for YRh6Ge4, LaRh6Ge4, and LuRh6Ge4. The compounds RERh6Ge4 ( RE = Gd-Yb) are Curie-Weiss paramagnets. Antiferromagnetic ordering was observed at 8.4(5) K (GdRh6Ge4), 13.6(5) K (TbRh6Ge4), 5.1(5) K (DyRh6Ge4), and 8.9(5) K (YbRh6Ge4). DyRh6Ge4 and YbRh6Ge4 show metamagnetic transitions at 2.5(5) and 45(2) kOe, respectively. [ABSTRACT FROM AUTHOR]

The quaternary germanides RE4Mn2InGe4 (RE = La-Nd, Sm, Gd-Tm, Lu) have been prepared by arc-melting reactions of the elements and annealing at 800°C and represent the second example of the RE4M2InGe4 series previously known only for M = Ni. Single-crystal X-ray diffraction studies conducted on the earlier RE members of RE4Mn2InGe4 confirmed that they adopt the monoclinic Ho4Ni2InGe4-type structure [space group C2/m, a = 16.646(2)-15.9808(9) Å, b = 4.4190(6)-4.2363(2) Å, c = 7.4834(10)--7.1590(4) Å, β = 106.893(2)-106.304(1)° in the progression of RE from La to Gd]. The covalent framework contains Mn-centered tetrahedra and Ge2 dimers that build up [Mn2Ge4] layers, which are held weakly together by four-coordinate In atoms and outline tunnels filled by the RE atoms. This bonding picture is supported by band-structure calculations. An alternative description based on Ge-centered trigonal prisms reveals that RE4Mn2InGe4 is closely related to RE2InGe2. The electrical resistivity behavior of Pr4Mn2InGe4 is similar to that of Pr2InGe2. [ABSTRACT FROM AUTHOR]

In this paper, state-of-the-art laser thermal annealing is used to form germanide contacts on n-doped Ge and is systematically compared with results generated by conventional rapid thermal annealing. Surface topography, interface quality, crystal structure, and material stoichiometry are explored for both annealing techniques. For electrical characterization, specific contact resistivity and thermal stability are extracted. It is shown that laser thermal annealing can produce a uniform contact with a remarkably smooth substrate interface with specific contact resistivity two to three orders of magnitude lower than the equivalent rapid thermal annealing case. It is shown that a specific contact resistivity of 2.84\times 10^-7~\Omega\cdotcm^2 is achieved for optimized laser thermal anneal energy density conditions. [ABSTRACT FROM AUTHOR]

Abstract: The title compounds were prepared by induction levitation melting of the elemental components and subsequent annealing. UMnGe (Pnma, a = 686.12(9), b = 425.49(6) and c = 736.5(1) pm) adopts the orthorhombic structure of TiNiSi and U2Mn3Ge (P63/mmc, a = 524.3(2) and c = 799.2(3) pm) possesses the hexagonal Mg2Cu3Si-type structure (ordered variant of the hexagonal Laves phase MgZn2). Both structures were refined from X-ray powder data to residuals of R I = 0.021 and 0.014 for UMnGe and U2Mn3Ge, respectively. The manganese and germanium atoms in UMnGe build up a three-dimensional [MnGe] network of ordered Mn3Ge3 hexagons with Mn–Ge distances ranging from 248 to 259 pm. The uranium atoms are coordinated by two tilted Mn3Ge3 hexagons. The manganese atoms in U2Mn3Ge build up Kagomé networks with 252 and 272 pm Mn–Mn distances which are connected via the germanium atoms (254 pm Mn–Ge) to a three-dimensional network. A remarkable feature of the U2Mn3Ge structure is a short U–U distance of 278 pm between adjacent cavities of the [Mn3Ge] network. From DFT based electronic structure calculations both germanides are found more cohesive than the Laves phase UMn2, thus underpinning the substantial role of Mn–Ge bonding. Calculations for both germanides show ferrimagnetic ground states with antiparallel spin alignments between U and Mn. The valence bands show bonding characteristics for interactions of atoms of different chemical natures and significant Mn–Mn bonding in U2Mn3Ge. Preliminary investigation of UMnGe by magnetization measurements confirms an antiferromagnetic arrangement below T N = 240 K. [Copyright &y& Elsevier]

Abstract: Phase analytical studies in the rare earth metal–zinc–germanium systems led to the synthesis of eight new ternary germanides. The compounds RE 4Zn5Ge6 (RE = Y, Dy, Ho, Er) crystallize with the orthorhombic Gd4Zn5Ge6 type structure, space group Cmc21. Er5Zn4−x Ge6 and the low-temperature modification of Tm5Zn4−x Ge6 adopt the Eu5Cd4−x Bi6 structure, while HT-Tm5Zn4−x Ge6 and Lu5Zn4−x Ge6 crystallize with a new type. All eight structures were refined on the basis of single crystal diffractometer data. The common structural motif is the distorted tetrahedral germanium coordination of the zinc atoms. The ZnGe4 tetrahedra are condensed via common edges and/or corners, leading to a two-dimensional polyanionic network in LT-Tm5Zn4−x Ge6 and three-dimensional ones in HT-Tm5Zn4−x Ge6 and Y4Zn5Ge6. In all three structure types part of the germanium atoms form dumb-bells with single bond character. The RE 4Zn5Ge6 germanides are electron-precise Zintl phases with an electron partitioning . This is different in the RE 5Zn4−x Ge6 phases. Both structure types of that composition show systematic defects on one zinc site. These zinc defects compensate the excess electron that would remain according to an electron partitioning . These crystal chemical features are supported by electronic structure calculations that reveal optimization of Zn–Ge and Ge–Ge bonding through lowering the Fermi energy. [Copyright &y& Elsevier]

The new equiatomic nickel germanides MgNiGe, SrNiGe, and BaNiGe have been synthesized from the elements in sealed tantalum tubes using a high-frequency furnace. The compounds were investigated by X-ray diffraction both on powders and single crystals. MgNiGe crystallizes with TiNiSi-type structure, space group Pnma, Z = 4, a=6A742(2) Å, b = 4.0716(1) Å, c = 6.9426(2) Å, wR2 = 0.033, 305 F² values, 20 variable parameters. SrNiGe and BaNiGe are isotypic and crystallize with anti-SnFCl-type structure (Z = 4, Pnma) with a = 5.727(1) Å, b = 4.174(l) Å, c = 11.400(3) A, wRz = 0.078, 354 -F² values, 20 variable parameters for SrNiGe, and a = 5.969(4) Å, b = 4.195(l) Å, c = 11.993(5) Å, wR2 = 0.048, 393 F² values, 20 variable parameters for BaNiGe. The increase of the cation size leads to a reduction of the dimensionality of the [NiGe] polyanions. In the MgNiGe structure the nickel and germanium atoms build a ∞³[NiGe] network with magnesium atoms in the channels. In SrNiGe and BaNiGe the ∞¹[NiGe] ribbons are separated by strontium/barium atoms, whereas in the known CaNiGe structure the ribbons are fused to two-dimmensional atom slabs. The crystal chemistry and chemical bonding in AeNiGe (Ae = Mg, Ca, Sr, Ba) are discussed. The experimental results are reconciled with electronic structure calculations performed using the tight-binding linear muffin-tin orbital (TB-LMTO-ASA) method. [ABSTRACT FROM AUTHOR]

Through arc-melting reactions of the elements and annealing at 800°C, the ternary rare-earth germanides RE 3Ru2Ge3 and RE 3Ir2Ge3 have been prepared for most of the smaller RE components (RE=Y, Gd–Tm, Lu). In the iridium-containing reactions, the new phases RE 2IrGe2 were also generally formed as by-products. Powder X-ray diffraction revealed orthorhombic Hf3Ni2Si3-type structures (space group Cmcm, Z=4) for RE 3 M 2Ge3 (M=Ru, Ir) and monoclinic Sc2CoSi2-type structures (space group C2/m, Z=4) for RE 2IrGe2. Full crystal structures were determined by single-crystal X-ray diffraction for all members of RE 3Ru2Ge3 (a=4.2477(6)Å, b=10.7672(16)Å, c=13.894(2)Å for RE=Y; a=4.2610(3)–4.2045(8)Å, b=10.9103(8)–10.561(2)Å, c=14.0263(10)–13.639(3)Å in the progression of RE from Gd to Lu) and for Tb3Ir2Ge3 (a=4.2937(3)Å, b=10.4868(7)Å, c=14.2373(10)Å). Both structures can be described in terms of CrB- and ThCr2Si2-type slabs built from Ge-centred trigonal prisms. However, band structure calculations on Y3Ru2Ge3 support an alternative description for RE 3 M 2Ge3 based on [M 2Ge3] layers built from linked MGe4 tetrahedra, which emphasizes the strong M–Ge covalent bonds present. The temperature dependence of the electrical resistivity of RE 3Ru2Ge3 generally indicates metallic behaviour but with low-temperature transitions visible for some members (RE=Gd, Tb, Dy) that are probably associated with magnetic ordering of the RE atoms. Anomalously, Y3Ru2Ge3 exhibits semiconductor-like behaviour of uncertain origin. Magnetic measurements on Dy3Ru2Ge3 reveal antiferromagnetic ordering at 3K and several unusual field-dependent transitions suggestive of complex spin reorientation processes. [ABSTRACT FROM AUTHOR]

Abstract: TbScGe is obtained as pure phase after melting of the constituents followed by an annealing at 1173K. Contrary to what was suggested previously, this ternary germanide does not present a high temperature form with the hexagonal Ti5Ga4-type structure after melting and quenching; the as quenched sample is a mixture based on the two solid solutions (Tb1− x Sc x )5Ge3 and Tb1− x Sc x . TbScGe adopts the tetragonal CeScSi-type structure with a =4.219 and c =15.452Å as unit cell parameters. Its investigation by magnetization and specific heat measurements reveals a ferromagnetic behavior below TC =250K inducing a moderate magnetocaloric effect; for a magnetic field change of 2T, the magnetic entropy change ΔSm is equal to −1.6JK−1 kg−1 which corresponds to an adiabatic temperature change ΔTad of 1.25K. [Copyright &y& Elsevier]

Abstract: Band structures of the pressure-induced, heavy-fermion superconductor Ce2Ni3Ge5 and its non-superconducting, mixed-valence isostructural (Ibam) counterpart Ce2Ni3Si5 have been calculated employing the full-potential local-orbital code. Both the local density approximation (LDA) and LDA+ U approaches were applied. These investigations were focused particularly on the topology of the Fermi surfaces (FSs) of the compounds. The results show that the FSs are quite similar in these systems and exist in four bands, containing three-dimensional holelike and electronlike sheets. However, the specific FS nesting properties has been revealed only in Ce2Ni3Ge5. They support a previously postulated presence of antiferromagnetic spin fluctuations (SF) in the heavy-fermion superconducting state of this germanide under pressure. Such SF can be responsible for the pressure-induced unconventional superconductivity in this system. [Copyright &y& Elsevier]

Six new rare-earth metal germanides with m-- general formula RE2Al1-xGe2+x (RE = Tb-Tm, Lu; 0.13(2) ≤ x ≤ 0.37(2)) have been synthesized by direct fusion of the corresponding elements. Their structures have been estab-lished by single-crystal diffraction to crystallize with the orthorhombic space group Immm (no. 74), adopting the W2CoB2 structure type. The A1 and Ge atoms are arranged in alternating planar layers, made of rhombic- and hexagonal-fragments. The rare-earth metal substructure consists of puckered four-connected nets. Electronic structure calculations support the coloring of the Ge and A1 sites and account for the existence of a small homogeneity range. DC magnetization measurements for all specimens are also presented; based on the RKKY and mean-field theories for antiferromagnets, relationships between the chemical bonding and exchange interactions are discussed. [ABSTRACT FROM AUTHOR]

Abstract: We report on the synthesis of Cu3Ge films by exposing Cu films to germane (GeH4). The process window was established by investigating the influence of the GeH4 partial pressure, the soak temperature, and the soak time on Cu films of different thickness. It is shown that short exposures of germane led to Cu-rich germanides, while an excessive GeH4 supply resulted in a Cu3Ge/Ge mixed phase. The germanidation reaction was found to be selective and required the prior removal of the native Cu oxide by in situ plasma cleaning. X-ray diffraction and transmission electron microscopy showed that the Cu3Ge films were crystalline as deposited in the orthorhombic phase and were textured. The films were homogenous in composition. Thin films consisted of Cu3Ge islands connected by a thin wetting layer. Fully continuous layers were however found for larger film thicknesses. The continuity of the Cu3Ge film was also found to be influenced by the pseudosubstrate: the films were more continuous on TaN/Ta than on SiO2. The electric properties of the Cu3Ge films on both TaN/Ta and SiO2 pseudosubstrates are presented and compared. [Copyright &y& Elsevier]

We report on detailed polarized small-angle neutron scattering on cubic FeGe in magnetic fields applied either along (transverse) the scattering vector or parallel (longitudinal) to the neutron beam. The (H, T) phase diagrams for all principal axes contain a segmented A-phase region just below the onset of magnetic order. Hexagonal Bragg-spot patterns were observed across the entire A-phase region for the longitudinal geometry. Scattering intensity was observed in parts of the A phase for both scattering configurations. Only in a distinct pocket (A1) was vanishing scattering intensity found in the transverse geometry. [ABSTRACT FROM AUTHOR]

Rare-earth metal germanides with the general formula RE4Ge7 (RE = La, Ce, Pr, Nd, Sm) have been synthesized using the In-flux technique. Their structures have been established from single-crystal and powder X-ray diifraction, and the structural elucidation has been aided by electron diffraction. These compounds represent superstructures of the a-ThSi2 structure type through the longand/ or short-range vacancy ordering. RE4Ge7, (RE = Pr, Nd, Sm) appear to be commensurately modulated 4-fold superstructure of REGe2-x (x = 1/4), while coexistence of commensurate and incommensurate modulation is revealed in the La- and Ce-analogues. These results shed more light on the structural evolution of the REGe2-x phases as function of the vacancy concentration and nature of the rare-earth metal. Measurements of the magnetic susceptibilities on well-characterized single-crystals show ferromagnetic, antiferromagnetic, and even spin-glass-like behaviors. Mean-field theory is used to evaluate the correlations between structural and magnetic property data. Measurements on the electrical resistivities and the heat capacities are also presented and discussed. [ABSTRACT FROM AUTHOR]

The syntheses and single-crystal and electronic structures of three new ternary lithium rare earth germanides, RE5− xLi xGe4 (RE = Nd, Sm and Gd; x≃ 1), namely tetrasamarium lithium tetragermanide (Sm3.97Li1.03Ge4), tetraneodymium lithium tetragermanide (Nd3.97Li1.03Ge4) and tetragadolinium lithium tetragermanide (Gd3.96Li1.03Ge4), are reported. All three compounds crystallize in the orthorhombic space group Pnma and adopt the Gd5Si4 structure type (Pearson code oP36). There are six atoms in the asymmetric unit: Li1 in Wyckoff site 4 c, RE1 in 8 d, RE2 in 8 d, Ge1 in 8 d, Ge2 in 4 c and Ge3 in 4 c. One of the RE sites, i.e. RE2, is statistically occupied by RE and Li atoms, accounting for the small deviation from ideal RE4LiGe4 stoichiometry. [ABSTRACT FROM AUTHOR]

We herein describe our investigation of the superconducting and magnetic properties of the rare-earth ternary germanide intermetallic compounds La2Pt3Ge5 and Pr2Pt3Ge5. Single crystals of La2Pt3Ge5 and Pr2Pt3Ge5 were synthesized using the high-temperature metal flux method. Both types of crystal formed in a U2Co3Si5-type orthorhombic structure (space group I bam). La2Pt3Ge5 showed the onset of superconducting phase transition at Tc = 8.1 K, which, to the best of our knowledge, is the highest Tc of all the R2M3X5 (R = rare-earth elements, M = transition metal, and X = s-p metal) superconductors, and from the specific heat data, it was found to have multigap superconductivity. Pr2Pt3Ge5 showed both a superconducting phase transition at Tc = 7.8 K and two antiferromagnetic transitions at TN1 = 3.5 K and TN2 = 4.2 K, which indicates the coexistence of superconductivity and magnetism. However, the correlation between the superconductivity and the magnetism was too weak to be observed. In its normal state, Pr2Pt3Ge5 revealed strong magnetic anisotropy, probably due to the crystalline electric field effect. [ABSTRACT FROM AUTHOR]

Abstract: Si1−x Ge x films were epitaxially grown on Si(001) substrates at various ratios of flow rates of Si2H6 and GeH4. Si1−x Ge x films were also selectively grown on Si windows through modified alternating gas supply manner, repeating the unit cycle which consists of the Si1−x Ge x growth step and Cl2 exposure step. Injection of Cl2 enhanced the selectivity of the selective growth of Si1−x Ge x by etching away the spurious nuclei or deposits formed on oxide area. The separate addition of Cl2 resulted in decrease of the growth rate and Ge concentration of Si1−x Ge x film. Meanwhile, Ge concentration in Si1−x Ge x films was insignificantly affected by the variation of the flow rates and exposure durations of Cl2. [Copyright &y& Elsevier]

Abstract: Single-crystals of the novel rare-earth metal-bismuth digermanides with idealized formula RE[Bi x Ge1−x ]2 (RE=Y, Pr, Nd, Sm, Gd–Tm, Lu; x<0.16(1)) have been obtained using the Bi-flux technique. Their structures have been established by single-crystal X-ray diffraction; they can be divided into three classes, closely related to the ZrSi2 structure with the space group Cmcm (no. 63). The structural relationship and the variations with the type of the rare-earth metal have been explored and discussed. Temperature-dependent magnetization measurements on the single-crystals reveal magnetic behavior, which have been rationalized based on the mean-field theory. At cryogenic temperatures, the localized 4f electrons in most of the compounds exhibit antiferromagnetic ordering, mediated by the conduction electrons via Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange interactions. [Copyright &y& Elsevier]

Abstract: Metal oxide semiconductor field effect transistors (MOSFET) with SiGe channel and higher-k gate dielectric are studied in this work. Samples with TaON/HfO2 or TiON/HfO2 stacks show larger drain current, better transconductance, and smaller subthreshold swing than that with single HfO2 layer. In addition, the reliability for SiGe pMOSFET device is clearly improved with TaON/HfO2 stacks in terms of degradation of Gm and Vth after hot-carrier stress. The integration of SiGe channel with TaON higher-k dielectric is useful for high performance pMOSFETs. [Copyright &y& Elsevier]

We use a first-principles rational-design approach to identify a previously unrecognized class of ferroelectric materials in the P63mc LiGaGe structure type. We calculate structural parameters, polarization, and ferroelectric well depths both for reported and as-yet hypothetical representatives of this class. Our results provide guidance for the experimental realization and further investigation of high-performance materials suitable for practical applications. [ABSTRACT FROM AUTHOR]

This paper demonstrates a scalable electrothermal model for transient self-heating effects in trench-isolated SiGe heterojunction bipolar transistors (HBTs). The scalability of the thermal model has been investigated by considering pyramidal heat diffusion approximation between the heat source and the thermal ground. Three-dimensional thermal TCAD simulations have been carried out to obtain transient variations of the junction temperature and to extract the thermal impedance in the frequency domain. A recursive thermal network with scalable model parameters has been developed and added at the temperature node of the HBT compact model HiCuM. This network has been verified through numerical simulations and by low-frequency s-parameter measurements and found to be in excellent agreement for various device geometries. [ABSTRACT FROM PUBLISHER]

Abstract: The origin of anomalous thermomagnetic irreversibility in rare earth germanide has been addressed. Open hysteresis observed in magnetoresistance (MR) at low temperature is shown to decrease with increasing temperature which correlates with the corresponding isothermal magnetostriction (MS) measurements. These thermomagnetic irreversibilities are interpreted in terms of kinetic arrest of magnetic field induced first order transition. The minor loop study of isothermal MS suggests that open loop in MS and MR is associated with large magnetostriction across metamagnetic transitions. The magnetoresistance associated with the second metamagnetic transition at higher field is reversible where magnetostriction variation with field is negligible. [Copyright &y& Elsevier]

The intermetallic compound Ca5Ni17Ge8 was prepared by arc melting mixtures of the elements and subsequent annealing under argon atmosphere. The compound crystallizes in a new structure type with the space group Amm2, Z = 2, a = 4.0255(2) Å, b = 25.226(2) Å, c = 8.9861(6) Å and wR2 = 0.083 (all data).Ca5Ni17Ge8 consists of a $\rm^{3}_{\infty}$[Ni17Ge8] network in whose cavities the calcium atoms are situated. The three-dimensional network comprises a unusual large diversity of structural motifs that are known from other compounds of the systems Ae/Ni/Ge ( Ae: Ca, Sr, Ba), such as the coordination environments of the calcium atoms reminiscent to those in Ca7Ni49Ge22 and Ca15Ni68Ge37 as well as various Ni-Ge structural motifs which occur similarly in Ca2Ni3Ge2, BaNi2Ge, SrNi2Ge, Ni3Sn2 and Ni3Sn. [ABSTRACT FROM AUTHOR]

Abstract: Nanoscaled SiGe particles (NPs) are formed by ions implantation and annealing treatment methods. For any sample, the total dose of Si and Ge dopants is 3×1016 cm−2. Strong photoluminescence (PL) peaks centered around red emission region are observed. This PL peak red shifts from 653nm–695nm with the increase of Ge-doping dose, which is ascribed to the quantum confinement effect. The PL lifetime spectra exhibit a stretched exponential decay with characteristic decay time τ varying from 50.2–23.1μs and dispersion factor β in the range of 0.67–0.86. [Copyright &y& Elsevier]

The Gibbs energy, enthalpy, and entropy of formation of HoGe (HoGe) and HoGe (HoGe) from solid compounds are determined by emf measurement in the temperature range 770-965 K. The formation enthalpy of the higher holmium germanide is in good agreement with ∆ H° (HoGe) calculated from the limiting mixing enthalpy of Ho in liquid germanium on the assumption that $ \varDelta {\bar{H}_{Ho}} $ for solid alloys in the [HoGe + Ge] region remains the same as $ \varDelta \bar{H}_{Ho}^\infty $ for liquid alloys. [ABSTRACT FROM AUTHOR]

Abstract: Non-equilibrium molecular dynamics (NEMD) simulation is performed to investigate thermal conductivities of two kinds of SiGe heterostructure nanowires (NWs), core(Si)/shell(Ge) and core(Ge)/(Si) NWs, using different interaction potentials between core and shell atoms. The influence of the proportion of core particles on the overall thermal conductivity of NWs is studied as well. Simulation results demonstrate that thermal conductivities of each kind of NWs with strong potential between core and shell atoms are higher than those of their counterparts with weak interaction between Si and Ge atoms. It is also found that thermal conductivities of both kinds of Si/Ge heterostructure NWs reduce with the decrease of the proportion of core atoms when the shell is not very thick. [Copyright &y& Elsevier]

Abstract: A large new family of rare-earth metal–cadmium–germanides RE2CdGe2 (RE=Y, Pr, Nd, Sm, Gd–Yb) has been synthesized and structurally characterized. All eleven structures have been established from single-crystal X-ray diffraction data and have been found to belong to the tetragonal Mo2FeB2 structure type (ordered ternary variant of the U3Si2 structure type—space group P4/mbm (No. 127), Z=2; Pearson symbol tP10). The structural variations among the three series of isostructural RE2MgGe2, RE2InGe2, and RE2CdGe2 compounds are discussed, as well as the crystal chemistry changes as a function of the decreasing size of the rare-earth metals (lattice constants a=7.176(2)–7.4589(12)Å and c=4.1273(14)–4.4356(13)Å). The experimental results have been complemented by tight-binding linear muffin-tin orbital (TB–LMTO) electronic structure calculations. [Copyright &y& Elsevier]

In this study we report the vortex-glass behavior of superconducting ternary germanide SrPd2Ge2 single crystals with a ThCr2Si2-type structure. We observed flux trapping and its nonexponential decay with time after the magnetic field was turned off at T = 2 K. In addition, we found that the diamagnetism in the zero field cooling (ZFC) mode below Tc was irreversible, depending on the temperature and field history, whereas the diamagnetism in the field-cooled warming (FCW) mode was reversible if the applied magnetic field was parallel to the c-axis. An irreversibility line Tr.(H) was determined by the ZFC and FCW measurements at various magnetic fields, and the temperature dependence of Tr.(H) was found to agree with the de Almeida-Thouless relation, H = H0[1 - Tr.(H)/Tc.(0)]&bgr;, where &bgr; 3/2. Including these vortex-glass behaviors, we discuss the critical current density, Jc.(T), determined from isothermal magnetization measurements at various temperatures, and the pinning potential, determined from the slope of an Arrhenius plot, ln R.(T, B) versus 1/T. [ABSTRACT FROM AUTHOR]

The intermetallic compound CeGe exhibits unusual magnetic behavior owing to the interplay between Kondo and antiferromagnetic coupling. This system is interesting because the Kondo temperature is close to the Néel temperature, so there is a close competition between the low-temperature interactions, which can be tuned by varying external parameters such as pressure and applied magnetic field. Interestingly, magnetization measurements up to 12 kbar reveal that the Néel temperature is not affected by pressure. Measurements of the electrical resistivity show, however, that the sharp upturn below TN is sensitive to pressures up to 15 kbar. This suggests that pressure may change the complex antiferromagnetic spin structure. The validity of an explanation based on the magnetic superzones seen in the rare earths is discussed here. [ABSTRACT FROM AUTHOR]

Abstract: The Pr-based ternary germanide Pr2Cu0.8Ge3 has been characterized by means of magnetization, heat capacity and electrical resistivity measurements. The compound has been found to order magnetically at T 1 = 13.4 K and then undergo two subsequent magnetic phase transitions at T 2 = 11.8 K and T 3 = 11.2 K. The magnetization and specific heat data indicate that the electronic ground state in Pr2Cu0.8Ge3 has a ferromagnetic-like character. [Copyright &y& Elsevier]

Abstract: The electronic structures of BaAlGe and SrAlGe which are superconductors with hexagonal honeycomb layers have been studied by using a first principles method. Energy bands, Fermi surfaces, and density of states are presented. The two materials have topologically different Fermi surfaces. BaAlGe has two Fermi surfaces: one has a three dimensional spinning-top-like shape and the other has a cylindrical shape with two dimensional character. SrAlGe has only one connected Fermi surface. Two gap superconductivity for BaAlGe is suggested from the inherently different character of the two Fermi surfaces. The higher T c of SrAlGe than BaAlGe is related to the difference in both the topology of the Fermi surface and the band dispersions along the z direction. [Copyright &y& Elsevier]

Abstract: This paper investigates the pull-in instability and free vibration of functionally graded poly-SiGe micro-beams under combined electrostatic force, intermolecular force and axial residual stress, with an emphasis on the effects of ground electrode shape, position-dependent material composition, and geometrically nonlinear deformation of the micro-beam. The differential quadrature (DQ) method is employed to solve the nonlinear differential governing equations to obtain the pull-in voltage and vibration frequencies of the clamped poly-SiGe micro-beams. The present analysis is validated through direct comparisons with published experimental results and excellent agreement has been achieved. A parametric study is conducted to investigate the effects of material composition, ground electrode shape, axial residual stress and geometrical nonlinearity on the pull-in voltage and frequency characteristics. [Copyright &y& Elsevier]

An efficient scattering process between the electron system in the L valley and the hole system in the Γ valley in Ge/SiGe quantum wells is identified. Its dependencies on excitation energy and carrier density are analyzed using spectrally and time-resolved pump-probe experiments. This carrier scattering causes an ultrafast heating of the hole system leading to an additional bleaching signature appearing a few tens of picoseconds after the excitation. Our findings are supported by microscopic calculations of the absorption spectra for various carrier densities and temperatures based on the semiconductor Bloch equations. Additionally, this scattering mechanism explains the enhanced free carrier absorption observed in previously reported pump-probe experiments. [ABSTRACT FROM AUTHOR]

Semitransparent dark-red or ruby-red moisture- and air-sensitive single crystals of A10+x[Ge9]2[W1-xNbxO4] (A = K, Rb; x = 0, 0.35) were obtained by high-temperature solid-state reactions. The crystal structure of the compounds was determined by single-crystal X-ray diffraction experiments. They crystallize in a new structure type (P21/c, Z = 4) with a = 13.908(1) Å, b = 15.909(1) Å, c = 17.383(1) Å, and β = 90.050(6)° for K10.35(1)[Ge9]2[W0.65(1)Nb0.35(1)O4]; a = 14.361(3) Å, b = 16.356(3) Å, c = 17.839(4) Å, and β = 90.01(3)° for Rb10.35(1)[Ge9]2[W0.65(1)Nb0.35(1)O4]; a = 13.8979(2) Å, b = 15.5390(3) Å, c = 17.4007(3) Å, and β = 90.188(1)° for K10[Ge9]2WO4; and a = 14.3230(7) Å, b = 15.9060(9) Å, c = 17.8634(9) Å, and β = 90.078(4)° for Rb10[Ge9]2WO4. The compounds contain discrete Ge94- Wade's nido clusters and WO42- (or NbO43-) anions, which are packed according to a hierarchical atom-to-cluster replacement of the Al2Cu prototype and are separated by K and Rb cations, respectively. The alkali metal atoms occupy the corresponding tetrahedral sites of the Al2Cu prototype. The amount of the alkali metal atoms on these diamagnetic compounds corresponds directly to the amount of W substituted by Nb. Thus, the transition metals W and Nb appear with oxidation numbers +6 and +5, respectively, in the vicinity of a [Ge9]4- polyanion. The crystals of the mixed salts were further characterized by Raman spectroscopy. The Raman data are in good agreement with the results from the X-ray structural analyses. [ABSTRACT FROM AUTHOR]

Reported are the syntheses, crystal structures, and magnetic susceptibilities of two series of closely related rare-earth metal-lithium germanides RE2Li2Ge3 and RE3Li4Ge4 (RE = La-Nd, Sm). All title compounds have been synthesized by reactions of the corresponding elements at high temperatures, and their structures have been established by single-crystal X-ray diffraction. RE2Li2Ge3 phases crystallize in the orthorhombic space group Cmcm (No. 63) with the Ce2Li2Ge3 structure type, while the RE3Li4Ge4 phases crystallize in the orthorhombic space group Immm (No. 71) with the Zr3Cu4Si4 structure type, respectively. Both of their structures can be recognized as the intergrowths of MgAl2Cu- and AlB2-like slabs, and these traits of the crystal chemistry are discussed. Temperature-dependent direct-current magnetization measurements indicate Curie-Weiss paramagnetism in the high-temperature regime for RE2Li2Ge3 and RE3Li4Ge4 (RE = Ce, Pr, Nd), while Sm2Li2Ge3 and Sm3Li4Ge4 exhibit Van Vleck-type paramagnetism. The data are consistent with the local-moment magnetism expected for RE3+ ground states. At temperatures below ca. 20 K, magnetic ordering transitions have been observed. The experimental results have been complemented by tight-binding linear muffin-tin orbital electronic-band-structure calculations. [ABSTRACT FROM AUTHOR]