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Abstract: In order to find the optimal conditions for sample preparation of the binary germanide Ba6Ge25, the germanium-rich part of the Ba–Ge phase diagram was redetermined by means of metallography, X-ray powder diffraction and differential thermal analysis. The temperature behavior of cubic Ba6Ge25 was investigated both on polycrystalline samples and single crystals. The temperature dependence of the lattice parameter exhibits two anomalies at about 180 and 230K, respectively, which are caused by a structure transformation in two steps with hysteresis. Powder (T=10–295K) and single-crystal (T=95–295K) X-ray diffraction studies confirm that the symmetry of Ba6Ge25 (space group P4132) remains unchanged within the entire temperature range. A reconstructive behavior of the structural transformation is observed, involving Ge–Ge bond breaking and barium cation displacements. Some Ge4 type atoms (∼28%) are so significantly displaced during cooling that Ge4–Ge6 bonds break and new three-bonded (3b)Ge− species (electron acceptors) are formed. Consequently, the number of charge carriers is reduced, affecting the physical properties. The reversible bond breaking involved in this process is a typical characteristic of a solid-state chemical reaction. [Copyright &y& Elsevier]

Abstract: The rare earth compounds RE2Ge2In (, Ce, Pr, Nd) were synthesized by arc-melting the elements under argon and investigated by X-ray diffraction on both powders and single crystals. The structures of the praseodymium and neodymium compounds have been refined on the basis of the single crystal data: Mo2FeB2 type, , , , , 272 values for Pr2Ge2In and , , , 317 values for Nd2Ge2In, with 12 variable parameters for each refinement. These structures can be considered as intergrowths of distorted AlB2 and CsCl related slabs of compositions REGe2 and REIn, respectively. The Geces within the AlB2 slabs are 253 pm for both Pr2Ge2In and Nd2Ge2In. Magnetic measurements have indicated that La2Ge2In is a diamagnet, whereas Ce2Ge2In, Pr2Ge2In and Nd2Ge2In exhibit localized magnetism of RE3+ ions with complex behavior at the lowest temperatures hinting at canted antiferromagnetism or spin glass freezing. All four compounds studied show metallic electrical conductivity. [Copyright &y& Elsevier]

The reaction of Ni with Ge, Si0.75Ge0.25 and Si using rapid thermal annealing (RTA) and in-situ annealing method at 400 °C produces different phases, as revealed by cross-sectional transmission electron microscopy (TEM). A uniform film of nickel germanide (NiGe) was formed at 400 °C for the Ni reaction with Ge using the in-situ annealing technique, whereas Ni3Ge2 and NiGe phases were found using the RTA method. For the reaction between Ni and Si, a highly textured NiSi film was obtained at 400 °C for RTA whereas Ni3Si2 and NiSi were found using the in-situ annealing method. On the other hand, a relatively uniform NiSiGe was formed using RTA; Ni3(Si1-yGey)2 and Ni(Si1-xGex) (x

CeCoGe, crystallizing in the tetragonal CeFeSi-type crystal structure, was studied by means of magnetization, electrical resistivity and neutron powder diffraction. The compound orders antiferromagnetically at TN=5.0(2) K. The magnetic structure is described by ferromagnetic (001) planes of Ce atoms, antiferromagnetically stacked along the c-axis with the sequence (+-+-). The cerium magnetic moments lie in the basal plane with a small value of μCe=0.38(5)μB at 1.5 K. This original structure is discussed in relation to those previously reported for other isotypic REMX compounds (RE=rare earth, M=Fe, Co, Ru and X=Si, Ge). [Copyright &y& Elsevier]

The ternary germanide CeCoGe and its hydride CeCoGeH crystallize in the tetragonal CeFeSi-type structure but the hydrogenation induces an anisotropic expansion of the unit cell parameters: a decreases (−3.1%) whereas c increases (+12.7%). These structural changes suggest that the hydrogen atoms occupy the [Ce4] tetrahedral sites empty in CeCoGe. Magnetization and electrical resistivity measurements evidence an interesting transition from antiferromagnetic ordering [CeCoGe; TN=5.0(2) K] to spin fluctuation behaviour [CeCoGeH; Tsf=13.3(5) K]. [Copyright &y& Elsevier]

Uranium manganese germanide, UMn2Ge2, crystallizes in body-centered tetragonal ThCr2Si2 structure with space group I4/mmm, a=3.993 A˚ and c=10.809 A˚ under ambient conditions. Energy dispersive X-ray diffraction was used to study the compression behavior of UMn2Ge2 in a diamond anvil cell. The sample was studied up to static pressure of 26 GPa and a reversible structural phase transition was observed at a pressure of 16.1 GPa. Unit cell parameters were determined up to 12.4 GPa and the calculated cell volumes were found to be well reproduced by a Murnaghan equation of state with K0=73.5 GPa and K′=11.4. The structure of the high-pressure phase above 16.0 GPa is quite complicated with very broad lines and could not be unambiguously determined with the available instrument resolution. [Copyright &y& Elsevier]

New germanides LuIrGe and Lu3Ir2Ge3 were synthesized by arc-melting of the elements under an argon atmosphere and subsequent annealing slightly below the melting point in water-cooled silica tubes in a high-frequency furnace. Both compounds have been investigated by X-ray diffraction on powders and single crystals: TiNiSi type, Pnma, a=668.10(8), b=420.15(6), c=754.4(1) pm, wR2=0.0913, 276 F2 values, 19 variables for LuIrGe and Hf3Ni2Si3 type, Cmcm, a=426.5(1), b=1019.1(2), c=1398.9(4) pm, wR2=0.0751, 515 F2 values, 28 variables for Lu3Ir2Ge3. Yb2IrGe2 was obtained by reaction of the elements in a sealed tantalum tube in a water-cooled sample chamber of a high-frequency furnace. This germanide adopts the Zr2CoSi2 type, C2/m, a=1027.1(8), b=422.8(2), c=1010.3(9) pm, β=116.64(9)°, wR2=0.1067, 630 F2 values, and 32 variables. Each germanide has one crystallographic iridium position with four germanium neighbours. The Ir&z.sbnd;Ge distances range from 246 to 268 pm. The strongly distorted IrGe4 tetrahedra are connected only by Ir&z.sbnd;Ge bonds in LuIrGe, while additional Ge&z.sbnd;Ge bonds occur in Yb2IrGe2 (255 and 269 pm) and Lu3Ir2Ge3 (268 pm). Together the iridium and germanium atoms built different three-dimensional [IrGe], [Ir2Ge3], and [IrGe2] polyanions in which the rare earth atoms fill channels. The crystal chemical similarities of the three structures are discussed. [Copyright &y& Elsevier]

The title compounds MxTa11−xGe8 (M=Ti, Zr, Hf) were prepared from the pure elements by arc-melting and subsequent induction heating at temperatures between 1200°C and 1400°C. X-ray powder diffraction studies of the samples were performed using the Guinier technique and the respective powder patterns were refined with a structure model based on the orthorhombic Cr11Ge8-structure type (oP76, Pnma). The homogeneity ranges of the compounds were determined to be 0.9 (M=Hf) by means of electron probe microanalysis. Chemical bonding, electronic structure and site preferences are discussed based on extended Hu¨ckel calculations performed on hypothetical binary Ta11Ge8. [Copyright &y& Elsevier]

Neutron powder diffraction investigations on Ce2Ni3Ge5 have been carried out. This compound adopts the U2Co3Si5-type structure (Ibam space group) with only one crystallographic site available for Ce atoms. Magnetisation measurements indicate that Ce2Ni3Ge5 undergoes two antiferromagnetic transitions at low temperature, at TN1=4.8(2) K and TN2=4.2(2) K, respectively. From our neutron diffraction experiments, only one transition is evidenced, below TN1, Ce2Ni3Ge5 is a collinear antiferromagnet with magnetic moments parallel to the a-axis and equal to 0.4(1) μB/Ce at T=1.4 K. [Copyright &y& Elsevier]

The germanides Ce 3 Rh 11 Ge 5 , Ce 6 Rh 30 Ge 19.5 , and CeRh 3 Ge 2 , which are new ternary Rh-rich phases in the Ce–Rh−Ge system, were prepared by reactions of the elements. Their crystal structures were determined by single-crystal and powder X-ray diffraction methods. Ce 3 Rh 11 Ge 5 adopts the Gd 3 Ru 4 Al 12 -type structure, which represents the fully stoichiometric version of the defect Sc 3 Ni 11 Ge 4 -type structure, in hexagonal space group P 6 3 / mmc with Z ​= ​2 and cell parameters a ​= ​8.6964 (12) Å and c ​= ​9.2209 (12) Å. Ce 6 Rh 30 Ge 19.5 is a filled derivative of the U 6 Co 30 Si 19 -type structure in hexagonal space group P 6 3 / m with Z ​= ​2 and cell parameters a ​= ​22.8480 (11) Å and c ​= ​3.9208 (2) Å. CeRh 3 Ge 2 is derived from a symmetry-lowered distortion of the hexagonal CeCo 3 B 2 -type (or substitutionally ordered CaCu 5 -type) structure, and crystallizes in orthorhombic space group Fmmm with Z ​= ​16 and cell parameters a ​= ​7.392 (6) Å, b ​= ​11.341 (9) Å, and c ​= ​19.66 (2) Å. As expected by their Rh-rich compositions, the three compounds exhibit extensive Rh–Rh bonding, but surprisingly, they also show some short Ge–Ge contacts. Analysis of the electron localization functions and Bader charges reveals that charge transfer takes place from Ce to Rh atoms, indicative of a polar character in the bonding in these intermetallic compounds. Examination of the Rh-rich region of the Ce–Rh−Ge phase diagram reveals the existence of three new phases with hexagonal (Ce 3 Rh 11 Ge 5 , Ce 6 Rh 30 Ge 19.5) and orthorhombic structures (CeRh 3 Ge 2). [Display omitted] • Ce 3 Rh 11 Ge 5 , Ce 6 Rh 30 Ge 19.5 , and CeRh 3 Ge 2 were prepared at 800 ​°C. • Ce 3 Rh 11 Ge 5 (Gd 3 Ru 4 Al 12 -type) contains a stacking of [Ce 3 Rh 3 Ge] and [Rh 8 Ge 4 ] nets. • Ce 6 Rh 30 Ge 19.5 (filled U 6 Co 30 Si 19 derivative) contains large triangular assemblies. • CeRh 3 Ge 2 (own type) adopts a unique orthorhombic distortion of CeCo 3 B 2 -type. • ELF analysis reveals Ce-to-Rh charge transfer and extensive Rh–Rh bonding. [ABSTRACT FROM AUTHOR]

The ternary rare-earth compounds exhibit interesting physical and structural properties. These structures changing composition and stoichiometry change drastically their magnetic properties. Some of them, based on chromium germanides were studied experimentally concerning their magnetic properties and up to our knowledge they were never studied theoretically explaining nature of their magnetic behaviour. In the presented work the nature and mechanism of the magnetic and electronic properties of rare-earth chromium germanides is presented. The magnetic and electronic properties of RCrGe2 and RCr0.3Ge2 (R = Tb, Dy, Ho or Er) were investigated theoretically applying plane-wave density functional theory/Pcrdcw-Burkc-Ernzcrhof methodology. The computational investigations were performed for the stoichiometric and nonstoichiomctric crystal structure with the space group Cmcm. The stoichiometry of the rare-earth chromium germanides compounds has significant effect on the magnetic properties of the investigated material. The theoretical predictions arc compared to the experimentally obtained results. [ABSTRACT FROM AUTHOR]

Investigates the conformation isomerism of nonagermanide ions. Isolation of brown and red form of the [K-([2.2.2]-crypt)]+ salts of naked polyhedral nonagermanide anions by dissolving the alloy K4Ge9 in ethylenediamine; Influence of the solvent molecules on the color of the crystals and the conformation of deltahedral anions; Paramagnetic properties of the anions.

• The A l B 2 -like structure is shown to be dynamically unstable for the S r A l G e compound. • A new dynamically stable strucural model with a doubled unit cell is proposed. • The correlation between electronic structure and dynamical stability is explored. • A peierls like distorsion is shown to primarly affect the A l − p z orbitals. • A puckring mode is shown to have the main contribution in the superconducting coupling mechanism. In the present investigation, based on density functional theory computational approach, we show how the experimentally accepted AlB 2 -like structure of the SrAlGe compound is suggested to be dynamically unstable at 0 K. We propose a stable configuration that is deduced from the detailed analysis of the phonon spectrum with a doubled unit cell and buckled AlGe layers. It allows to closely reproduce the experimental critical superconducting temperature assuming a phonon mediated superconductivity as described within BCS theory. A soft puckering mode is identified both as the cause for the structural instability and as the main contributor in the electron-phonon coupling constant. From the detailed study of the electronic structure, we show how a peierls-like distortion with the crystal symmetry lowering, affecting mainly the Al- p z orbitals, is correlated with the puckering and with the electron-phonon coupling mechanism. [ABSTRACT FROM AUTHOR]

Highlights: [•] We discovered that the new germanide superconductors of A8(Al,Ge)46 (A=Rb, Cs). [•] The superconducting transition temperature is confirmed at around 3.6 K for A = Rb and 4 K for A = Cs. [•] The M–H curve at 1.8K shows that the Rb8(Al,Ge)46 belongs to a type-II superconductor. [ABSTRACT FROM AUTHOR]

Poor ohmic contact by Fermi-level pinning to valence band (EV) edge is one of the major challenges for germanium (Ge) n-type metal-oxide-semiconductor field-effect transistor (nMOSFET). Using low work-function rare-earth ytterbium (Yb), good ohmic contact on n-type Ge with alleviated Fermi-level pinning was demonstrated. Such ohmic behavior depends strongly on the germanide formation condition, where much degraded ohmic contact at 600 °C rapid thermal annealing is due to the lower Yb/Ge composition found by energy-dispersive x-ray spectroscopy. The ohmic behavior of Yb-germanide/n-type-Ge has high potential for future high-performance Ge nMOSFET application. [ABSTRACT FROM AUTHOR]

We report high-performance p-channel \Omega-gate germanium (Ge) p-channel multigate field-effect transistor (MuGFET) with low-temperature \Si2\H6 surface passivation and Schottky-barrier nickel germanide (NiGe) metallic source/drain, fabricated on high-quality germanium-on-insulator (GeOI) substrates using sub-400 ^\circ\C process modules. As compared with other reported p-channel multigate Ge devices formed by top–down approaches, the Ge MuGFETs in this letter have a record-high on-state current ION of \sim \450\ \mu\A/\mu\m at VGS - VTH = -\1\ \V and VDS = -\1\ \V. High peak intrinsic saturation transconductance of \sim \740\ \mu\S/\mu\m and low off-state current are reported. We also study the effect of fin or channel doping on Ge MuGFET performance. The simple MuGFET process developed using GeOI substrate would be a good reference for future 3-D Ge device fabrication. [ABSTRACT FROM AUTHOR]

In this letter, we report the demonstration of an effective electron Schottky barrier height (ΦBn) reduction technology for NiGe/n-type Germanium (n-Ge) contacts using ion implantation of selenium (Se) followed by its segregation at NiGe/n-Ge interface. Se was found to segregate at NiGe/n-Ge interface after germanide formation. Nickel monogermanide was formed using a 350°C 30-s anneal. Se segregation gives ΦBn as low as ~0.13 eV. [ABSTRACT FROM PUBLISHER]

In this work, nickel germanide Schottky contacts have been fabricated on n-type germanium (n-Ge) with an optimum barrier height of 0.63 eV. For rapid thermal annealing (RTA) temperatures above 300 °C, all phases of nickel and germanium convert to nickel mono-germanide (NiGe). However, higher RTA temperatures are also found to cause agglomeration of the NiGe phase and higher leakage current. So, the optimum temperature for Schottky-based source/drain contact formation on n-Ge is ∼300 °C, where the nickel mono-germanide phase is formed but without phase agglomeration. [ABSTRACT FROM AUTHOR]

We report on the redistribution of Sn during Ni germanide formation on Ge1-xSnx/ and its influence on the thin film growth and properties. These results show that the reaction involves the formation of Ni5Ge3 and NiGe. Sn redistributes homogenously in both phases, in which the Sn/Ge ratio retains the ratio of the as-deposited Ge1-xSnx film. Sn continues to diffuse after full NiGe formation and segregates in two regions: (1) at the interface between the germanide and Ge1-xSnx and (2) at the surface, which has major implications for the thin film and contact properties. [ABSTRACT FROM AUTHOR]

Nickel germanide contacts are expected to play an important role in Ge-based electronics similar to that of their nickel silicide counterparts in Si devices. Here we have studied the solid state reaction between Ni contact pads and Ge nanowires. We observe the formation of axial nickel germanide segments after annealing at temperatures as low as 300 °C for 2 min. The nickel germanide segments are polycrystalline, without an epitaxial relationship to the Ge nanowire, in contrast to observations of epitaxial nickel silicide formation from Si nanowires. The crystal structure of the nickel germanide phase is consistent with the Ni2In prototype structure. Annealing above 400 °C results in fracture in the nickel germanide segment; however, nickel germanide segments as long as 1.7 μm can be formed by annealing at 400 °C for 5 min. [ABSTRACT FROM AUTHOR]

The thermal stability of a nickel germanide film formed on a tensile-strained Ge epilayer on a silicon substrate with a low-temperature Si0.77Ge0.23 (50-nm)/Ge (50-nm) buffer is investigated. A record temperature of 700 °C for the stability of sheet resistance of nickel germanide is reported, which is increased by about 150 °C compared to that on bulk Ge and comparable to the temperature for nickel silicide on the Si substrate. The improvement of the thermal stability is demonstrated due to the delay of the agglomeration of the nickel germanide film on Ge-on-Si, which is proposed to be attributed to the increase of the tensile strain in the Ge epilayer during thermal annealing due to the thermal mismatch between Si and Ge. [ABSTRACT FROM AUTHOR]

Abstract: Magnetization isotherms for polycrystalline TbMnGe and DyMnGe compounds were measured at the temperature 4.2K in pulsed magnetic fields (up to 360kOe). The received isotherms demonstrate the appearance of metamagnetic transitions at low temperatures. Both compounds crystallize in the orthorhombic TiNiSi-type structure. It was found that the magnetic phase transitions with a destruction of ferrimagnetic spiral structure occur in the TbMnGe and DyMnGe compounds in high magnetic fields. An attempt was undertaken to explain the nature of these transitions using the results of the powder neutron diffraction and the qualitative estimation of the exchange interaction values on the basis of the molecular field theory. [Copyright &y& Elsevier]

Abstract: The Grating Light Valve (GLV) is a microelectromechanical reflection grating. It operates on the principle of controlled diffraction of incident light due to electrostatic deflection of microbeams, thus producing bright and dark pixels in a display system. This unique approach offers significant advantages compared to other display systems in terms of speed, high optical efficiency, accuracy and ease of manufacturing. At the same time monolithic integration of MEMS on top of CMOS is getting more popular because CMOS-integrated MEMS exhibit less parasitics and have a reduced assembly and packaging cost over hybrid approaches. The relatively low deposition temperature (∼450°C) of poly-SiGe compared to poly-Si (∼800°C) makes poly-SiGe suitable for back end processing. Hence, in this work we report the fabrication and functioning of CVD poly-SiGe GLVs in terms of their response to the amplitude and frequency of the applied actuation voltage. [Copyright &y& Elsevier]

The reaction of GeBr with LiGe(SiMe3)3 yields the largest metalloid cluster compound of germanium Ge14[Ge(SiMe3)3]5Li3(THF)6, in which 14 germanium atoms are arranged as a hollow sphere in the cluster core, showing that in the case of germanium also fullerene-like compounds might be present in the borderland between the molecular and solid states. [ABSTRACT FROM AUTHOR]

Abstract: Low temperature specific heat measurements are performed in a novel ternary superconductor La3Pd4Ge4, which forms U3Ni4Si4-type crystal structure consisting of the combination of alternating units of AlB2- and BaAl4 (ThCr2Si2)-type layers. The Sommerfeld coefficient and the Debye temperature are derived from the normal state specific heat. The electron–phonon coupling constant and the electronic density of states at the Fermi level are also derived. Temperature dependence of the superconducting electronic specific heat is well described by the BCS exponential behavior with gap . The results suggest La3Pd4Ge4 has fully opened isotropic gap in the superconducting state. [Copyright &y& Elsevier]

The thermal stability of NiGe films formed on epitaxial Ge on Si substrates was improved from 450 to 550 °C by simply adding an ultrathin (∼1 nm) Ti layer during Ni deposition, either as an intermediate layer between Ni and Ge or as a capping layer on Ni. The improvement was attributed to the formation of ternary Ni1-xTixGe phase near the NiGe surface, which acts as a capping layer to suppress agglomeration of the underlying NiGe film at an elevated temperature, as well as modification of the NiGe grain boundaries. The resistivity of NiGe is also slightly reduced by the Ti incorporation, making this method very promising for the germanium technology. [ABSTRACT FROM AUTHOR]

• The R 2 PdGe 6 (R = Pr, Nd, Gd-Er) and R 2 PtGe 6 (R = Tb, Ho, Er) intermetallics are investigated. • The compounds crystallize in the orthorhombic crystal structure (S.G. Cmca). • An antiferromagnetic order is observed at low temperatures (4.9 ≤ T N ≤ 48 K). • Both collinear and noncollinear magnetic structures are determined. • A transition to modulated magnetic structure is found in Nd 2 PdGe 6 in vicinity of T N. Polycrystalline samples of the intermetallic compounds R 2 PdGe 6 (R = Pr, Nd, Gd-Er) and R 2 PtGe 6 (R = Tb, Ho, Er) have been studied using X-ray diffraction as well as magnetometric and neutron diffraction measurements. All compounds have an orthorhombic crystal structure of the Yb 2 PdGe 6 -type (space group Cmca) and are antiferromagnetic with the Néel temperatures ranging from 4.9 K for Er 2 PtGe 6 up to 48 K for Tb 2 PdGe 6. The magnetic properties and specific heat data collected for Nd 2 PdGe 6 show the presence of an additional phase transition below T N at T = 4 K. Based on the neutron diffraction data, the magnetic structures have been determined for R 2 PdGe 6 (R = Pr, Nd, Tb, Dy, Ho) and R 2 PtGe 6 (R = Tb and Er). Both the magnetic properties and neutron diffraction data indicate that the magnetic moment is localized on rare earth atoms. The magnetic unit cell is equal to the crystal one, however, individual compounds show different types of magnetic orderings. Magnetic moments in Pr 2 PdGe 6 form a non-collinear antiferromagnetic structure at low temperatures with magnetic moments confined to the (0 0 1) plane. The low temperature magnetic structure in Nd 2 PdGe 6 is a collinear antiferromagnetic one with moments parallel to the b-axis and coupled ferromagnetically within the (0 0 1) plane, while along the c-axis the moments follow the + − − + sequence. With increasing temperature, a transition to a modulated magnetic structure is observed in Nd 2 PdGe 6 at T = 4 K. The magnetic moments in R 2 PdGe 6 (R = Tb, Dy, Ho) and Tb 2 PtGe 6 assume a non-collinear antiferromagnetic order within the (0 0 1) plane with the + − + − sequence of signs of the moments in the neighboring planes along the c-axis. The Er moments in Er 2 PtGe 6 form a collinear magnetic structure with magnetic moments oriented along the a-axis and coupled ferromagnetically within the (0 0 1) plane. Along the c-axis the moments follow the + − + − sequence. The magnetic structures determined here are discussed on the basis of the competition between the RKKY-type interactions and influence of Crystalline Electric Field. [ABSTRACT FROM AUTHOR]

Pulsed laser deposition and post-annealing was used for the preparation of MnSi x and MnGe x thin layers in order to study the increase of ferromagnetic properties related to crystalline phases. As-prepared samples were mainly amorphous with Mn concentration ranging from 20 to 50 at.%. Annealing of MnSi x and MnGe x layers at 600 °C and 350 °C, respectively, led to the formation of crystalline nanoparticles with the diameter from 10 to 20 nm. Magnetization measured at 300 K showed that the annealed MnSi x layers exhibited magnetization of 0.07 μB/Mn atom. Magnetization of annealed MnGe x layers varied depending on Mn concentration from 0.1 μB/Mn atom (30 at.%) to 0.4 μB/Mn atom (47 at.%). Resistivity measurements of the annealed layers showed values typical for highly degenerate silicon (~10−3.Ω m) and germanium (~10−5.Ω m). Temperature dependence of resistivity revealed that, after annealing, only MnSi x layers with lower Mn concentration preserved a semiconducting behaviour. • Growth of silicide and germanide nanoparticles by reactive pulsed laser deposition. • Ferromagnetic properties of manganese-silicon and manganese-germanium thin layers. • Resistivity measurement of manganese-silicon and manganese-germanium thin layers. [ABSTRACT FROM AUTHOR]

The nickel monogermanide (NiGe) phase is known for its electrical properties such as low ohmic and low contact resistance in group-IV-based electronics. In this work, thin films of nickel germanides (Ni–Ge) were formed by magnetron sputtering followed by flash lamp annealing (FLA). The formation of NiGe was investigated on three types of substrates: on amorphous (a-Ge) as well as polycrystalline Ge (poly-Ge) and on monocrystalline (100)-Ge (c-Ge) wafers. Substrate and NiGe structure characterization was performed by Raman, TEM, and XRD analyses. Hall Effect and four-point-probe measurements were used to characterize the films electrically. NiGe layers were successfully formed on different Ge substrates using 3-ms FLA. Electrical as well as XRD and TEM measurements are revealing the formation of Ni-rich hexagonal and cubic phases at lower temperatures accompanied by the formation of the low-resistivity orthorhombic NiGe phase. At higher annealing temperatures, Ni-rich phases are transforming into NiGe, as long as the supply of Ge is ensured. NiGe layer formation on a-Ge is accompanied by metal-induced crystallization and its elevated electrical resistivity compared with that of poly-Ge and c-Ge substrates. Specific resistivities for 30 nm Ni on Ge were determined to be 13.5 μΩ·cm for poly-Ge, 14.6 μΩ·cm for c-Ge, and 20.1 μΩ·cm for a-Ge. [ABSTRACT FROM AUTHOR]

The reaction between nanometric Ni films and Ge is analyzed using isothermal x-ray diffraction measurements and transmission electron microscopy. It is found that NiGe is formed during deposition at room temperature. The metal rich phase that grows during heat treatment has been clearly identified to be Ni5Ge3. The simultaneous growths of Ni5Ge3 and NiGe have been observed on amorphous and polycrystalline germanium. This is in contrast with the usual sequential growth reported in thin films. [ABSTRACT FROM AUTHOR]

Crystal qualities of Si/SiGe/Si-on-insulator structures with different SiGe thicknesses were evaluated by photoluminescence (PL). The wafers were annealed at different temperatures with a ramping rate of 5 °C/min. Free exciton PL peaks were clearly observed for the as-grown wafers and decreased with an increase in the annealing temperature. For the annealed wafers, defect-related PL signals were observed at around 0.82, 0.88, 0.95, and 1.0 eV, which varied according to the annealing temperature and the SiGe thickness. They were also correlated to dislocation-related defects by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

We have investigated the thermal stability of nickel monogermanide (NiGe) films formed by rapid thermal annealing on both single- and polycrystalline Ge substrates. We found that the NiGe phase is the only one present after nickel germanidation in the temperature range 400–700 °C. A fairly uniform NiGe film formed on the single-crystalline Ge; it possessed excellent resistivity (15.6 μΩ cm) and was thermally stable up to 550 °C, but it degraded rapidly at higher temperatures as a result of agglomeration. In contrast, the NiGe film formed on the polycrystalline Ge exhibited much poorer thermal stability, possibly because of polycrystalline Ge grain growth, which resulted in columnar NiGe grains interlaced with Ge grains that had a dramatically increased sheet resistance. As a result, we observed that the sheet resistances of NiGe lines subjected to annealing at 500 °C depended strongly on the linewidth when this width was comparable with the grain size of the polycrystalline Ge. [ABSTRACT FROM AUTHOR]

The evolution of the He-implantation induced defect structure in SiGe/Si heterostructures is observed during in situ annealing at 650 and 800 °C within a transmission electron microscope. The He implantation and annealing results in the formation of He precipitates below the SiGe/Si interface, which at first show a platelike shape and subsequently decay into spherical bubbles. The coarsening mechanism of the He bubbles is revealed as coalescence via movement of entire bubbles. The nucleation of dislocation loops at overpressurized He platelets and their propagation into the heterostructure could be observed as well. We found distinctly different velocities of the dislocations which we attribute to glide and climb processes. The in situ experiments clearly show that the He platelets act as internal dislocation sources and play a key role in the relaxation of SiGe layers. [ABSTRACT FROM AUTHOR]

Reflectance difference (RD) spectra for the a–b plane of the single crystals of Gd[sub 5]Si[sub 2]Ge[sub 2] and b–c planes of Gd[sub 5]Si[sub 2]Ge[sub 2] and Tb[sub 5]Si[sub 2.2]Ge[sub 1.8] were obtained in the photon energy range of 1.5–5.5 eV. Several peaks were observed for these crystals in the measured spectrum range. Similar features were observed in the RD spectra for the b–c planes of Gd[sub 5]Si[sub 2]Ge[sub 2] and Tb[sub 5]Si[sub 2.2]Ge[sub 1.8], while different features were observed for the a–b plane and b–c plane of Gd[sub 5]Si[sub 2]Ge[sub 2]. The RD spectra for the crystals arise not only from the surface anisotropy but also from the bulk anisotropy due to the monoclinic structure of the bulk crystal. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A micropower-relevant model is extracted from the DC characteristics of an n-type buried channel Si/SiGe hetero-junction modulation doped FET (HMODFET). This model is then used to design a novel monolithic SiGe single-stage class-A power amplifier for micropower operation (sub 500 µW). The amplifier is fabricated and measured data of the power-gain against operating power are presented for the first time. [ABSTRACT FROM AUTHOR]

Presents a study which examined the structural, electronic and magnetic properties of the cobalt[sub2]manganese germanide Heusler compound. Experimental details; Results and discussion; Conclusion.