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The Ta–Ge system was thermodynamically modeled for the first time using the CALPHAD method incorporating both literature-derived phase equilibria data and new enthalpy of formation values for the intermetallic compounds. Density Functional Theory (DFT) calculations were employed to accurately determine enthalpy of formation values for key Ta–Ge compounds. The stable intermetallic phases (i.e., αTa 3 Ge, βTa 3 Ge, βTa 5 Ge 3 , and TaGe 2) were described as stoichiometric phases while the Liquid (L), Ta-rich solid solution (BCC-A2), and Ge-rich solid solution (Diamond-A4) were modeled as solution phases using the Compound Energy Formalism. Excess terms were described by the Redlich-Kister polynomials. The present thermodynamic model accurately describes phase equilibria and thermodynamic data, providing a reliable guide for designing alloys containing Ta and Ge. [ABSTRACT FROM AUTHOR]

The magnetic properties and magnetic structures of the R 2 TGe 6 compounds (T = Ni and Cu, R = Tb, Ho and Er) were studied by magnetometric and neutron diffraction measurements. All compounds have an orthorhombic crystal structure of the Ce 2 CuGe 6 -type and are antiferromagnetic with the Néel temperatures ranging from 6 K for Er 2 CuGe 6 up to 42 K for Tb 2 NiGe 6. Based on the neutron diffraction data the magnetic structures were determined for R 2 NiGe 6 (R = Tb, Er) and R 2 CuGe 6 (R = Ho, Er). In these compounds the magnetic moments localized on the rare earth element form a collinear commensurate magnetic structure. The magnetic unit cell is equal to the crystal one in R 2 NiGe 6 (R = Tb, Er) while it is doubled along the a-axis (propagation vector k = (½, 0, 0)) in R 2 CuGe 6 (R = Ho and Er). The obtained magnetic structures are discussed on the basis of competition between the RKKY-type interactions and influence of Crystalline Electric Field (CEF). • Neutron diffraction and magnetic data for R 2 TGe 6 are reported. • The compounds crystallize in the orthorhombic Ce 2 CuGe 6 -type structure. • R 2 TGe 6 (R = Nd, Tb, Ho, Er; T = Ni, Cu) are collinear antiferromagnets. • Magnetic structure depends on the R and T elements involved. [ABSTRACT FROM AUTHOR]

Abstract A systematic study on the existence of R 2 Pd 3 Ge 5 intermetallics with heavy rare earth metals (R = Gd–Lu) was conducted; only the Yb 2 Pd 3 Ge 5 was revealed to exist. Its crystal structure was established by X-ray powder diffraction and refined by means of Rietveld method. This compound crystallizes in the orthorhombic U 2 Co 3 Si 5 structure type (Ibam , oI 40, Z = 4, a = 10.2628(1), b = 12.0580(1), and c = 5.98251(6) Å), which represents an ordered derivative of the tI 10-ThCr 2 Si 2 prototype, ubiquitous among intermetallics. Magnetization and susceptibility measurements indicate that Yb 2 Pd 3 Ge 5 is a paramagnet with μ eff close to 0.8 μ B /Yb-atom, suggesting a nearly divalent Yb state. Electrical resistivity and Seebeck coefficient of the studied compound as a function of temperature confirm its metallic-like behavior. Highlights • Only Yb 2 Pd 3 Ge 5 was revealed to exist among R 2 Pd 3 Ge 5 intermetallics (R = Gd÷Lu). • Yb 2 Pd 3 Ge 5 crystallizes in the orthorhombic U 2 Co 3 Si 5 structure type (Ibam , oI 40, Z = 4). • Magnetic properties measurements confirm a nearly divalent Yb state in Yb 2 Pd 3 Ge 5. • Electrical resistivity studies confirm metallic-like behavior of Yb 2 Pd 3 Ge 5. [ABSTRACT FROM AUTHOR]

Magnetic and transport properties of triangular-lattice Ni 1.8 Ge single crystal have been studied. The results reveal that Ni 1.8 Ge is a metal with an obvious magnetic anisotropy. The compound exhibits ferrimagnetic correlations along both directions. However, the long-range magnetic order was not observed due to the geometrical frustration arising from the triangular nickel lattice. At low temperature, the electron-magnon scattering and spin fluctuation have obvious contributions to the resistivity and magnetoresistance, indicating the existence of short-range dynamic magnetic ordering. [ABSTRACT FROM AUTHOR]

We investigated nano-floating gate memory having a charge trap layer (CTL) composed of cobalt germanide nanostructure (ns-CoGe). A tunneling oxide layer; a CTL containing Co, Ge, and Si; and a blocking oxide layer were sequentially deposited on a p-type silicon substrate by RF magnetron sputtering and low-pressure chemical vapor deposition. We optimized the CTL formation conditions by rapid thermal annealing at a somewhat low temperature (about 830 °C) by considering the differences in Gibbs free energy and chemical enthalpy among the components. To characterize the charge storage properties, capacitance–voltage ( C – V ) measurements were performed. Further, we used X-ray photoelectron spectroscopy for chemical analysis of the CTL. In this work, we not only report that the C – V measurement shows a remarkable opening of the memory window for the ns-CoGe compared with those of nanostructures composed of Co or Ge alone, but also clarify that the improvement in the memory characteristics originates in the nanostructure formation, which consists mainly of Co-Ge bonds. We expect ns-CoGe to be a strong candidate for fabrication of next-generation memory devices. [ABSTRACT FROM AUTHOR]

URu 0.29 Ge 2 is a new germanide crystallizing in a monoclinic structure (C2/c space group, lattice parameters: a  = 4.098(1) Å, b  = 15.936(3) Å, c  = 4.045(1) Å and β  = 90.091(2)°) derived from the CeNiSi 2 -type. It undergoes a ferromagnetic ordering at T C  = 63 K, which manifests itself as distinct anomalies in temperature variations of the magnetization, specific heat and electrical resistivity. Just below T C , the T-dependent resistivity exhibits a broad hump, which hints at complex magnetic structure of the compound, while below 5 K it shows an upturn that likely arises due to atomic disorder in the crystal lattice. [ABSTRACT FROM AUTHOR]

Experimentally studied F-43m structured Li 2 ZnGe ternary germanide is investigated theoretically by evaluating the electronic structure, thermodynamic stability and thermoelectric efficiency using the full-potential method. The calculated lattice parameter and structural characterization agree well with the experimental results. The thermoelectric properties are calculated within the temperature range of 0–1200 K. The computed value of figure of merit is 0.40 at 1200 K and Seebeck coefficient is 150 μV/K specifying n-type nature. The electrical conductivity is high mainly due to high carrier mobility, while total thermal conductivity is moderate due to low lattice thermal conductivity. The estimated figure of merit projects it as a potential thermoelectric material for high temperature power generation. [ABSTRACT FROM AUTHOR]

A novel ternary intermetallic germanide CeIrGe 2 has been studied by means of x-ray diffraction, magnetization, specific heat and electrical resistivity measurements, performed in wide ranges of temperature and external magnetic fields. The compound crystallizes in an orthorhombic structure of the CeNiSi 2 -type (space group Cmcm ). It exhibits a Kondo lattice behavior and orders antiferromagnetically at 4 K. [ABSTRACT FROM AUTHOR]

The electrical properties of Cu-germanide(Cu 3 Ge)/n-type Ge Schottky contacts formed as a result of a solid state reaction between Cu and n-type Ge were investigated as a function of the rapid thermal annealing (RTA) temperature and correlated with its microstructural evolution driven by the RTA process. The variations of the barrier height of Cu 3 Ge/n-type Ge Schottky rectifiers caused by the RTA process were determined using current-voltage ( I - V ) and capacitance-voltage ( C - V ) methods. The Cu 3 Ge film formed after annealing at 400 °C exhibited a relatively uniform surface and interface morphology. This led to the formation of a laterally homogenous Schottky barrier in the Cu 3 Ge/n-type Ge Schottky diode, resulting in an improvement of its rectifying I - V behavior. On the other hand, after annealing above 500 °C, the Cu 3 Ge film was severely agglomerated without film continuity and eventually evolved into isolated islands at 600 °C. Such structural degradation of Cu 3 Ge led to a rapid decrease in the barrier height and an increase in the reverse leakage current of the Cu 3 Ge/n-type Ge Schottky diode. The electric field dependence of the reverse current showed that the reverse leakage current in the Cu 3 Ge/n-type Ge Schottky diodes was dominated by a Poole-Frenkel emission mechanism, regardless of the RTA temperatures. [ABSTRACT FROM AUTHOR]

The new ternary intermetallic with high content of germanium, CeRuGe 5 , was found in the course of reinvestigation of the Ce-Ru-Ge system at 700 °C. The compound crystallizes in the tetragonal structure of new type (space group I 4/ mcm ) with the unit cell parameters: a = 6.1414(6) Å, c = 13.751(3) Å, Z = 4, Pearson symbol tI 28. The structure of CeRuGe 5 can be presented as [CeGe 3 ] and [RuGe 2 ] slabs alternating along the tetragonal c -axis. It is shown that the new structure of CeRuGe 5 and the known before structure of Sm 2 Ru 5 Ga 9 are derivatives from the common prototype – HoCoGa 5 . By means of magnetic, heat capacity and electrical transport measurements, the novel compound CeRuGe 5 was established to be a metallic Curie-Weiss paramagnet due to stable 4 f 1 electronic configuration of trivalent Ce ions. No intrinsic long-range magnetic ordering was found down to 1.7 K. [ABSTRACT FROM AUTHOR]

The structure and the chemical composition of Pd germanides formed on Ge(100) were investigated using transmission electron microscopy (TEM), in-situ X-ray diffraction (XRD), and atom probe tomography (APT). An ultrathin Si film used as a marker was deposited on Ge(100) prior to Pd film deposition in order to identify the diffusing species during the Pd 2 Ge growth. The observations evidenced the formation of a thin interfacial polycrystalline Pd 2 Ge layer during Pd room-temperature deposition on Ge(100). In-situ XRD thermal treatments ranging from 50 to 400 °C revealed that the Si marker had no influence on the sequential formation of Pd 2 Ge and PdGe. Ex situ APT and TEM characterizations showed that the Si marker layer was located closer to the Pd 2 Ge/Ge interface than to the Pd 2 Ge surface, after reaction. This result indicates that Ge and Pd self-diffusion are in the same order of magnitude during Pd 2 Ge growth. [ABSTRACT FROM AUTHOR]

Pd-Ge reactive-diffusion in two different samples Pd/Ge(001) and Pd/PdGe/Ge(001) was studied experimentally and theoretically, in order to clearly identify the driving force controlling the first-phase selection in the sequential phase formation regime. The experimental and theoretical results both show that only the atomic transport kinetic in the phases controls the first-phase selection: the phase exhibiting the fastest atomic self-diffusion forms first, even if its formation energy is not the lowest. [ABSTRACT FROM AUTHOR]

We have investigated the microstructural and electrical properties of Cu-germanides formed by the deposition of Cu on Ge wafer, followed by rapid thermal annealing (RTA) process at the temperatures in the range of 300–700 °C. Regardless of RTA temperature, the Cu 3 Ge was the only phase formed as a result of solid-state reaction between Cu and Ge driven by RTA process. The RTA temperature dependency of specific contact resistivity of Cu 3 Ge was explained in terms of its structural evolution caused by RTA process. The RTA process at 400 °C led to the formation of Cu 3 Ge film having highly uniform surface and interface morphologies, allowing the minimum value of the specific contact resistivity. The samples annealed above 500 °C underwent the severe structural degradation of Cu 3 Ge, resulting in a rapid increase in the specific contact resistivity. After RTA at 700 °C, pyramidal Cu 3 Ge islands standing on a corner, distributed along Ge <110> direction were formed with epitaxial relationship on underlying Ge. [ABSTRACT FROM AUTHOR]

The crystal structure of a novel CePd 12 Ge 2 intermetallic was determined and refined from single-crystal X-ray diffraction data. The compound crystallizes in a tetragonal structure of a new type: space group I 4 1 md (No. 109), cell parameters a = b = 12.0819(9) Å, c = 6.4554(7) Å, V = 942.3(2) Å3, Z = 4. In a crystallographic unit cell, Ce atoms occupy one Wyckoff site (4 a). Two (16 c) sites and two (8 b) sites are filled with Pd atoms. One more position (8 b) is occupied by Ge atoms. An analysis of the features of the crystal structure revealed its relationship with the known binary type BaCd 11. Magnetic and transport properties of CePd 12 Ge 2 were studied. The results obtained show no signs of long-range magnetic ordering down to 1.7 K. However some hints on magnetic ordering below T ≈ 1.7 K may be proposed from magnetoresistance data. We also register low temperature logarithmic rise of resistivity indicating the main role of Kondo interactions in CePd 12 Ge 2. • New ternary germanide CePd12Ge2 found. • CePd 12 Ge 2 crystallizes in a tetragonal structure of a new type. • CePd 12 Ge 2 is a pronounced Kondo system. [ABSTRACT FROM AUTHOR]

The 3 × 3 R 30 ° structures of 2-D nickel silicide and nickel germanide surface alloys on Ni(111) were investigated using quantitative low-energy electron diffraction analysis. The unit cells of the determined silicide and germanide structures contain two Ni atoms and one Si or Ge atom, corresponding to the chemical compositions Ni 2 Si and Ni 2 Ge, respectively. Both the Si and Ge atoms adopt substitutional face-centered cubic hollow sites to sit on the Ni(111) substrates, and the alloy surfaces exhibit a slight corrugation. The Ni Si and Ni Ge distances were 2.44 and 2.56 Å, respectively, and corresponded well to their respective empirical radii. It was also found that the Ni atoms in the second and third layers moved toward the Si or Ge atom sites from their bulk crystal positions. These results indicate rather strong interactions of the Ni atoms with both the Si and Ge atoms at the surface, leading to trapping of the Si and Ge atoms at the substitutional sites without diffusion into the bulk. [ABSTRACT FROM AUTHOR]

We investigated the crystalline structure of a NiGe layer grown on Ge(0 0 1) substrate through the reactive deposition method. NiGe layers grown at 350 °C are a single crystalline, provided that they are thin enough—below 22 nm. The epitaxial relationship with the Ge(0 0 1) substrate is then as follows: NiGe(1 1 1)//Ge(0 0 1), and NiGe[0 1 ¯ 1]//Ge[1 1 0]. However, the NiGe layer becomes polycrystalline when the thickness reaches 22 nm or thicker. We proposed a two-step deposition method combined with solid-phase reaction to suppress the polycrystalline formation and successfully achieved an epitaxial NiGe layer over 22 nm-thick with an atomically flat interface. We also clarified that the Ge atom is the dominant diffusion species during the reactive deposition and that the Ni atom dominates during the solid-phase reaction. [ABSTRACT FROM AUTHOR]

In this work, the effect of dopant segregation on the NiGe/n-Ge contact is studied by experiments and first-principles calculations. Both Al-contacted and NiGe-contacted n + /p junctions were fabricated. Phosphorus and arsenic ions were Implanted Before Germanide (IBG) formation or Implanted After Germanide (IAG) formation. The NiGe-contacted junction always exhibit higher forward current than the Al-contacted junction due to dopant segregation. First principles calculations predict that phosphorus atoms tend to segregate on both NiGe side and Ge side while arsenic atoms tend to segregate at Ge side. Since phosphorus has higher activation level and lower diffusion coefficient than arsenic, we propose a phosphorus IBG + arsenic IAG process. Shallow n + /p junction with junction depth 90 nm below the NiGe/Ge interface is achieved. The lowest and average contact resistivity is 2 × 10 −6 Ω cm 2 and 6.7 × 10 −6 Ω cm 2 , respectively. Methods which can further reduce the junction depth and contact resistivity are suggested. [ABSTRACT FROM AUTHOR]

Phase relations have been established by electron probe microanalysis (EPMA) and X-ray powder diffraction (XPD) for the Sr-poor part of four ternary systems: Sr–{Pd,Pt}–Si at 900 °C and Sr–{Pd,Pt}–Ge at 700 °C. In the Sr–Pd–Si system the formation of the silicide SrPdSi 3 (BaNiSn 3 -type) was confirmed and a small homogeneity region was found. Furthermore, two novel compounds were detected and their crystal structure was refined from X-ray powder patterns: SrPd 0.3 Si 1.7 (AlB 2 -type) and SrPd 5.9 Si 6.1 (own-type). In the Sr–Pt–Si ternary system a novel compound with AlB 2 -type was discovered (SrPt 0.3 Si 1.7 ), whereas SrPtSi 3 with the BaNiSn 3 -type was confirmed. Two more compounds were detected by EPMA, but their crystal structure remains unknown. In the Sr–{Pd,Pt}–Ge systems no new compounds were observed, but the existence of SrPdGe 3 and SrPtGe 3 (both adopt the BaNiSn 3 structure type), and SrPt 4 Ge 12 , crystallizing in the LaFe 4 Sb 12 structure type, was corroborated. For selected ternary silicides the electronic structure was evaluated by DFT calculations. [ABSTRACT FROM AUTHOR]

The germanides Sc T Ge ( T = Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au) were obtained in X-ray pure form by arc-melting of the elements. The structures of the members with T = Co, Ni, Cu, Rh, Pd, Ag, Ir, and Pt were refined on the basis of single crystal X-ray diffractometer data. The germanides with T = Cu, Ru, Pd, Ag crystallize with the hexagonal ZrNiAl type structure, space group P 6 ¯ 2 m and those with T = Co, Ni, Rh, Ir, Pt adopt the orthorhombic TiNiSi type. ScAuGe is isotypic with NdPtSb. All germanides exhibit single scandium sites. A simple systematization of the structure type according to the valence electron concentration is not possible. The 45 Sc solid state NMR parameters (Knight shifts and nuclear electric quadrupole coupling constants) of those members crystallizing in the TiNiSi structure show systematic trends as a function of valence electron concentration number. Furthermore, within each T -group the Knight shift decreases with increasing atomic number; this correlation also includes previously published results on the isotypic silicide family. The 45 Sc quadrupolar interaction tensor components are generally well-reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code. [ABSTRACT FROM AUTHOR]

The germanide ScFe 6 Ge 4 was synthesized from the elements by arc-melting. Its crystal structure was refined from single crystal X-ray diffractometer data: LiFe 6 Ge 4 type, R 3 ¯ m , a = 507.9(3), c = 2000.9(1) pm, wR 2 = 0.0737, 242 F 2 values, 16 variables. The structure has two main building units. The iron atoms form double-layers of Kagomé networks (248–297 pm Fe–Fe) which are separated by layers of edge-sharing Sc@Ge 8 hexagonal bipyramids (265–293 pm Sc–Ge). Chemical bonding has been studied based on DFT calculations for the A Fe 6 Ge 4 ( A = Li, Sc, Zr) series and isotypic LuTi 6 Sn 4 . Existence of MgFe 6 Ge 4 is proposed on the basis of full geometry optimization. Major differences are observed between the electronic structures and the magnetic properties and bonding of LuTi 6 Sn 4 on the one hand and the A Fe 6 Ge 4 family on the other hand whereby the iron Kagomé substructure develops magnetization in all A Fe 6 Ge 4 compounds, in contrast to LuTi 6 Sn 4 . The Ti–Ti Kagomé substructure is found with bonding character throughout the valence band whereas Fe–Fe interactions are both bonding and antibonding with characteristic spin-dependent bonding. Spin-polarized calculations hint for magnetic ordering in the iron containing representatives. This was proven experimentally for ScFe 6 Ge 4 . Temperature-dependent susceptibility measurements show a Curie temperature of T C = 491(3) K. 57 Fe Mössbauer spectroscopic measurements at ambient temperature show a single resonance at an isomer shift of 0.22(1) mm s −1 with a magnetic hyperfine field of 19.1(1) T . [ABSTRACT FROM AUTHOR]

We report on the determination of the crystal structure of Mn 9 Co 3 Ge 5 from single crystal X-rays diffraction (SG: R32; a = 6.9697 Å; c = 16.4707 Å). The new phase is isotypic of the binary compound Mn 12 Ge 5 and it is also observed in the ternary diagrams Mn–Fe–Ge and Mn–Ni–Ge. According to powder X-rays diffraction, the compound Mn 12 Ge 5 corresponds to the unknown Mn 7 Ge 3 ( κ ) phase previously reported in the Mn–Ge binary phase diagram. The new type may be viewed as a Ge deficient Ni 2 In-type Mn 2 Ge 1 − x structure with an ordering of the Ge vacancies in a rhombohedral 9-times larger cell. [ABSTRACT FROM AUTHOR]

Highlights: [•] RE3Mn2Ge3 are the first Mn-containing members of Hf3Ni2Si3-type germanides. [•] Crystal structures of Ce3Mn2Ge3 and Nd4Mn2Ge5O0.6 were determined. [•] Double-chains of MnGe4 tetrahedra are an important building block. [•] RE3Mn2Ge3 exhibits complex antiferromagnetic ordering. [Copyright &y& Elsevier]

Abstract: The total and partial density of states, electronic charge density and optical properties of the monoclinic structure K10Ge18WO4 compound have been investigated using a full relativistic version of the full-potential augmented plane-wave method based on the density functional theory, within local density approximation (LDA), generalized gradient approximation (GGA) and Engel-Vosko GGA (EVGGA). Density of states discloses the semiconductor nature of the calculated compound. There exists a strong hybridization between K-p and K-s, W-d and O-p, W-f and K-p. The analysis of the chemical bonding shows that the bonding possesses strong covalent nature. The dielectric optical properties were also calculated and discussed in detail. The electrical transport coefficients of the under observation compound have been investigated using the density functional theory calculation within EVGGA. [Copyright &y& Elsevier]

Highlights: [•] We study phase formation in the Ni–Ge thin film system using in situ XRD and TEM. [•] We deposited Ni films with different Ge concentrations using combinatorial sputtering. [•] A metastable germanide was observed when adding between 36 and 48 at.‰Ge. [•] When adding between 36 and 42 at.% Ge, this phase is already present as-deposited. [ABSTRACT FROM AUTHOR]

Highlights: [•] Neutron diffraction study was performed on the germanides R15Ge9C (R=Ce, Pr, Nd). [•] The interstitial carbon atoms occupy mainly the site 2b in (1/32/3∼1/2). [•] The three compounds display canted ferromagnetic structures with k =[000]. [•] Carbon insertion strongly modifies the magnetic properties of the parent germanides. [Copyright &y& Elsevier]

We have investigated the epitaxial formation and electrical properties of Ni germanide/Ge(110) contacts. X-ray diffraction and transmission electron microscopy measurements have revealed that Ni5Ge3 and NiGe layers are epitaxially formed on a Ge(110) substrate after annealing at 200–350°C. An epitaxial Ni5Ge3 layer is formed after annealing with the relationships Ni5Ge3(001)//Ge(110) and Ni5Ge3[311]//Ge[001]. We found that the orientation relationship between an epitaxial NiGe layer and Ge(110) substrate depends on the annealing temperature. When annealed at 300–350°C, the orientation relationship is NiGe(100)//Ge(110) and NiGe[001]//Ge[001], while at 200–230°C, the relationship is NiGe(102)//Ge(110) and NiGe[010]//Ge[001]. We demonstrate that the Schottky barrier height of the epitaxial NiGe(100)/Ge(110) contact is as low as 0.44eV, as estimated from the current density–voltage characteristics, while that of polycrystalline NiGe/Ge(001) is 0.55eV. [ABSTRACT FROM AUTHOR]

Abstract: Solid state reactions between Ge and Mn films are systematically examined using X-ray diffraction, photoelectron spectroscopy, and magnetic and electrical measurements. The films have a nominal atomic ratio Ge:Mn=20:80 and are investigated at temperatures from 50 to 500ºC. It is established that after annealing at ~120ºC, the ferromagnetic Mn5Ge3 phase is the first phase to form at the 20Ge/80Mn interface. As the annealing temperature increases to 300ºC, the weak magnetic Mn5Ge2 +Mn3Ge phases simultaneously begin to grow and they become dominant at 400ºC. Increasing the annealing temperature to 500ºC leads to the formation of the ferromagnetic phase with a Curie temperature TC ~350–360K and magnetization 14–25kA/m at room temperature. The X-ray diffraction study of the samples shows the reflections from the Mn5Ge3 phase, and the photoelectron spectra contain the oxygen and carbon peaks. The homogeneous distribution of oxygen and carbon over the sample thickness suggests that the increased Curie temperature and magnetization are related to the migration of C and O atoms into the Mn5Ge3 lattice and the formation of the Nowotny phase Mn5Ge3СxOy. The initiation temperature (~120°С) is the same in the Mn5Ge3 phase with the solid-state reactions in the Ge/Mn films as well as in the phase separation in the GexMn1−x diluted semiconductors. Thus, we conclude that the synthesis of the Mn5Ge3 phase is the moving force for the spinodal decomposition of the GexMn1−x diluted semiconductors. [Copyright &y& Elsevier]

Abstract: The solid state reaction between 30nm Pd films and various Ge substrates (Ge(100), Ge(111), polycrystalline Ge and amorphous Ge) was studied by means of in situ X-ray diffraction and in situ sheet resistance measurements. The reported phase sequence of Pd2Ge followed by PdGe was verified on all substrates. The texture of the germanides was analysed by pole figure measurements on samples quenched in the Pd2Ge and in the PdGe phase on both Ge(100) and (111) substrates. We report an epitaxial growth of Pd2Ge on Ge(111) and on Ge(100). The formed PdGe has an axiotaxial alignment on Ge(111). On Ge(100), the axiotaxial texture is observed together with a fibre texture. The higher formation temperature of PdGe on Ge(111) could be related to the epitaxial alignment of the Pd2Ge parent phase on Ge(111). [Copyright &y& Elsevier]

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]

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]

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]

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]

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: 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]

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]

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]

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: 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]

Abstract: The new ternary mixed lanthanum stannide/germanide La55Sn36.6Ge24.4 (orthorhombic, space group Cmcm, a =2373.98(5), b =2375.52(6), c =2378.64(5)pm, Z =4, R1=0.0728) was synthesized from stoichiometric melts of the three elements. Its complex structure contains a great variety of different tetrel anions, some known from the binary border compounds and new unusual Ge/Sn structural units: isolated Ge atoms (octahedrally coordinated by La), isolated Sn atoms (coordinated by 10 La cations), bent trimers [Sn3] and four-membered planar rings [Sn4] are also present in binary La germanides and stannides (i.e. La11Sn10, La3Sn4 or l.t.-LaSn). New tetrele anions are the eight-membered planar chain pieces [M8] (M=Ge, Sn), which exhibit both cis, trans and also linear conformation. Despite the presence of several mixed Ge/Sn sites, a tendency towards an alternation of Ge and Sn in the chain is apparent. The only extended structural elements of the title compound are polyanions [M24] consisting of eight-membered Ge rings, in which all atoms are bonded in a trigonal-planar geometry. In two directions, these rings are connected via two-bonded M pairs to form ribbons. In the orthogonal direction, two five-membered chain pieces are connected, which are similar in conformation and Ge/Sn distribution to the [M8] chains. The remaining four Ge atoms of the ring are connected to terminal tin atoms. The diversity of the anions and particularly the different conformations of the planar chains in La55Sn36.6Ge24.4 allows not only a comparison with the respective binary La germanides and stannides but also a study on the ‘coloring’ in tetrelides and a detailed analysis of the bond lengths of two-bonded Ge and Sn atoms. Despite the complex structure and the variety of tetrelide anions, a simple electron count reveals the title compound to be an electron precise Zintl phase. [Copyright &y& Elsevier]

Abstract: Self-assembled iron germanide nanowires (NWs) were grown by directly depositing Fe onto a Ge (110) substrate, in an in situ ultra-high vacuum transmission electron microscope from 430 to 500°C. All observed NWs had a similar length/width aspect ratio (∼8:1) at all deposition temperatures, as well as the same elongation orientation with respect to the underlying Ge (110) substrate. The growth dynamics was investigated by real time observations of NWs growth at elevated temperatures. It is elucidated that the formation of NWs in similar shape at all deposited temperatures is attributed to the similar activation energy barriers in length and width of NWs, which can result in the constant growth rate independent of growth temperatures. Furthermore, the difference in pre-exponential factor along the length and width of growing islands arose due to the anisotropic constraint of the Ge (110) substrate, leading to the unique elongation of NWs. This growth dynamics suggests the possibility of uniform control of the morphology of self-assembled NWs, as well as other morphologies of bottom-up fabricated devices, at different deposition temperatures. [Copyright &y& Elsevier]

Abstract: We examined the formation and morphological evolution of germanide formed in a ternary Ni/Zr-interlayer/Ge system using ex situ and in situ annealing experiments. Ni germanide in the Ni/Zr-interlayer/Ge system remained stable at temperatures up to 550°C whereas Ni germanide in a Ni/Ge system agglomerated and was unstable. Microstructural and chemical analyses of the Ni/Zr-interlayer/Ge system during and after in situ annealing in a transmission electron microscope confirmed that the Zr atoms were retained uniformly on the top region of the Ni germanide layer during the diffusion reaction. Ultimately, the level of agglomeration in the Ni germanide film was reduced by the Zr-interlayer, and the thermal stability of Ni germanide was improved. [Copyright &y& Elsevier]

Abstract: We have investigated the rapid thermal annealing behavior of electrical and microstructural properties of Ti (30nm) and Pt (30nm) contacts to n-type Ge substrates before and after rapid thermal annealing (RTA) at the temperatures in the range of 500–700°C for 30s under N2 ambient. Despite low work function, Ti contacts exhibited Schottky behavior at low RTA temperatures due to strong Fermi level pinning (FLP) effect. However, the Ti contacts showed Ohmic behavior after annealing at 700°C. Similarly, the Pt contacts formed at low temperatures annealing showed Schottky behavior as usually expected from Schottky–Mott theory. However, the annealing of Pt contacts at higher temperature (700°C) resulted in the Ohmic behavior. For both contacts, the abrupt transition of Schottky to Ohmic behavior could be associated with the significant increase in the leakage current under reverse bias condition caused by structural degradation of Ti- and Pt-germanide films. [Copyright &y& Elsevier]

Abstract: Mg germanide nanorods were successfully fabricated by interdiffusion of the Mg into Ge nanorods on Si substrates at 425 oC for 0.5h. It was observed that the Mg2Ge nanorod structures were formed by an interdiffusion process between the deposited Mg atoms and the Ge nanorods. Moreover, Mg2Si nanorods were formed by additional interdiffusion between the Mg2Ge nanorods and the Si substrates at 425 oC for 4h. The structural properties of the Mg2Ge and Mg2Si nanorods were characterized, and the growth evolution of the structural and morphological properties of the nanorods was discussed. [Copyright &y& Elsevier]

Abstract: We report on the optical property investigation of SiGe nanocrystals (NCs) prepared by electrochemical anodization (ECA) of SiGe layer grown by ultrahigh vacuum chemical vapor deposition (UHVCVD). At room temperature, SiGe NCs with higher Ge content demonstrate a redshift of the photoluminescence (PL) peak compared to Si NCs. It was found that the surface chemical composition, density, and the size of the SiGe NCs were very sensitive to the annealing conditions. Various spectroscopy measurements such as PL, FTIR, and XPS have been carried out to reveal the mechanism of the PL peak transition. The results indicated that the PL peak position was determined by two major factors, namely, interface state density and the size of SiGe NCs. It was shown that the higher the interface state density, the more significant the redshift of the peak position. While the smaller the size of the SiGe NCs, the more significant the quantum size effects become, resulting in the blueshift of the PL peak position. [Copyright &y& Elsevier]

Abstract: A new ternary compound, U9Fe7Ge24, was synthesized by arc-melting the elements, followed by annealing at 900 °C. This compound was characterized by single crystal and powder X-ray diffraction, magnetization, specific heat and electrical transport measurements. It crystallizes in an original tetragonal structure type (space group I4/mmm), with lattice parameters a = 12.3789(2) Å and c = 18.2881(3) Å. Three uranium, eighth germanium, and three iron crystallographic sites exist in this structure, with the atoms making a stacking of infinite chains along the a and b axis. From their interatomic distances strong interactions between the uranium and germanium atoms can be predicted. The magnetic and specific heat measurements down to 2 K do not show any magnetic transition. The Curie–Weiss behaviour with a negative paramagnetic Curie temperature θp = −94 K and reduced effective magnetic moment of μ eff = 2.13 μB/U indicate that the compound is rather far from onset of magnetism, presumably due to a strong hybridisation of the 5f and ligand states. The electrical transport measurements show a metallic behaviour. [Copyright &y& Elsevier]

Abstract: We have investigated the crystalline orientation dependence of the electrical properties of Mn germanide/Ge(111) and (001) Schottky contacts. We prepared epitaxial and polycrystalline Mn5Ge3 layers on Ge(111) and (001) substrates, respectively. The Schottky barrier height (SBH) estimated from the current density-voltage characteristics for epitaxial Mn5Ge3/Ge(111) is as low as 0.30eV, while the SBH of polycrystalline Mn5Ge3/Ge(001) is higher than 0.56eV. On the other hand, the SBH estimated from capacitance–voltage characteristics are higher than 0.6eV for both samples. The difference of these SBHs can be explained by the local carrier conduction through the small area with the low SBH regions in the epitaxial Mn5Ge3/Ge(111) contact. This result suggests the possibility that the lowering SBH takes place due to Fermi level depinning in epitaxial germanide/Ge(111) contacts. [Copyright &y& Elsevier]