Synthesis of High Sn Content GeSiSn (0.1 < < 0.22) Semiconductors on Si for MWIR Direct Band Gap Applications.

A systematic effort has been described to grow ternary GeSiSn semiconductors on silicon with high Sn concentrations spanning the 9.5-21.2% range.

Fabrication of Ge:Ga Hyperdoped Materials and Devices Using CMOS-Compatible Ga and Ge Hydride Chemistries.

We report a versatile chemical vapor deposition (CVD) method to dope Ge films with Ga atoms in situ over a wide concentration range spanning from 3 × 10 to 2.7 × 10 cm. The method introduces a stable and volatile Ga hydride [DGaN(CH)] that reacts readily with GeH to deliver Ga dopants controllably and systematically at complementary metal-oxide-semiconductor compatible ultralow temperatures of ∼360 °C.

Synthesis and Structural and Optical Properties of Ga(AsP)Ge and (GaP)Ge Semiconductors Using Interface-Engineered Group IV Platforms.

Epitaxial synthesis of Ga(AsP)Ge alloys on Si(100) substrates is demonstrated using chemical vapor deposition reactions of [DGaN(CH)] with P(GeH) and As(GeH) precursors. These compounds are chosen to promote the formation of GaAsGe and GaPGe building blocks which interlink to produce the desired crystalline product. Ge-rich (GaP)Ge analogues have also been grown with tunable Ge contents up to 90% by reactions of P(GeH) with [DGaN(CH)] under similar deposition protocols.

Observation of Phase-Filling Singularities in the Optical Dielectric Function of Highly Doped n-Type Ge.

Phase-filling singularities in the optical response function of highly doped (>10^{19}  cm^{-3}) germanium are theoretically predicted and experimentally confirmed using spectroscopic ellipsometry. Contrary to direct-gap semiconductors, which display the well-known Burstein-Moss phenomenology upon doping, the critical point in the joint density of electronic states associated with the partially filled conduction band in n-Ge corresponds to the so-called E_{1} and E_{1}+Δ_{1} transitions, which are two-dimensional in character. As a result of this reduced dimensionality, there is no edge shift induced by Pauli blocking.

Ultralow Resistivity Ge:Sb heterostructures on Si Using Hydride Epitaxy of Deuterated Stibine and Trigermane.

The nonconventional deuterated stibine (SbD3) compound has been used for the first time in combination with trigermane (Ge3H8) to produce hyper-doped Ge-on-Si films with carrier concentrations n > 10(20) cm(-3) and record-low resistivities ρ = 1.8 × 10(-4) Ω cm. The growth takes place on Ge and Ge1-xSix buffered Si(100) wafers at ultralow temperatures (∼330 °C) at which Sb diffusion is negligible, leading to extremely flat atomic profiles of the constituents.

Rational design of monocrystalline (InP)(y)Ge(5-2y)/Ge/Si(100) semiconductors: synthesis and optical properties.

In this work, we extend our strategy previously developed to synthesize functional, crystalline Si(5-2y)(AlX)y {X = N,P,As} semiconductors to a new class of Ge-III-V hybrid compounds, leading to the creation of (InP)(y)Ge(5-2y) analogues. The compounds are grown directly on Ge-buffered Si(100) substrates using gas source MBE by tuning the interaction between Ge-based P(GeH3)3 precursors and In atoms to yield nanoscale "In-P-Ge3" building blocks, which then confer their molecular structure and composition to form the target solids via complete elimination of H2. The collateral production of reactive germylene (GeH2), via partial decomposition of P(GeH3)3, is achieved by simple adjustment of the deposition conditions, leading to controlled Ge enrichment of the solid product relative to the stoichiometric InPGe3 composition.

Molecular synthesis of high-performance near-IR photodetectors with independently tunable structural and optical properties based on Si-Ge-Sn.

This Article describes the development of an optimized chemistry-based synthesis method, supported by a purpose-built reactor technology, to produce the next generation of Ge(1-x-y)Si(x)Sn(y) materials on conventional Si(100) and Ge(100) platforms at gas-source molecular epitaxy conditions. Technologically relevant alloy compositions (1-5% Sn, 4-20% Si) are grown at ultralow temperatures (330-290 °C) using highly reactive tetragermane (Ge(4)H(10)), tetrasilane (Si(4)H(10)), and stannane (SnD(4)) hydride precursors, allowing the simultaneous increase of Si and Sn content (at a fixed Si/Sn ratio near 4) for the purpose of tuning the bandgap while maintaining lattice-matching to Ge. First principles thermochemistry studies were used to explain stability and reactivity differences between the Si/Ge hydride sources in terms of a complex interplay among the isomeric species, and provide guidance for optimizing process conditions.

Nanosynthesis routes to new tetrahedral crystalline solids: silicon-like Si3AlP.

We introduce a synthetic strategy to access functional semiconductors with general formula A(3)XY (A = IV, X-Y = III-V) representing a new class within the long-sought family of group IV/III-V hybrid compounds. The method is based on molecular precursors that combine purposely designed polar/nonpolar bonding at the nanoscale, potentially allowing precise engineering of structural and optical properties, including lattice dimensions and band structure. In this Article, we demonstrate the feasibility of the proposed strategy by growing a new monocrystalline AlPSi(3) phase on Si substrates via tailored interactions of P(SiH(3))(3) and Al atoms using gas source (GS) MBE.

Ether-like Si-Ge hydrides for applications in synthesis of nanostructured semiconductors and dielectrics.

Hydrolysis reactions of silyl-germyl triflates are used to produce ether-like Si-Ge hydride compounds including H(3)SiOSiH(3) and the previously unknown O(SiH(2)GeH(3))(2). The structural, energetic and vibrational properties of the latter were investigated by experimental and quantum chemical simulation methods. A combined Raman, infrared and theoretical analysis indicated that the compound consists of an equal mixture of linear and gauche isomers in analogy to the butane-like H(3)GeSiH(2)SiH(2)GeH(3) with an exceedingly small torsional barrier of approximately 0.

Synthesis and fundamental properties of stable Ph(3)SnSiH(3) and Ph(3)SnGeH(3) hydrides: model compounds for the design of Si-Ge-Sn photonic alloys.

The compounds Ph(3)SnSiH(3) and Ph(3)SnGeH(3) (Ph = C(6)H(5)) have been synthesized as colorless solids containing Sn-MH(3) (M = Si, Ge) moieties that are stable in air despite the presence of multiple and highly reactive Si-H and Ge-H bonds. These molecules are of interest since they represent potential model compounds for the design of new classes of IR semiconductors in the Si-Ge-Sn system. Their unexpected stability and high solubility also makes them a safe, convenient, and potentially useful delivery source of -SiH(3) and -GeH(3) ligands in molecular synthesis.

Molecular-based synthetic approach to new group IV materials for high-efficiency, low-cost solar cells and Si-based optoelectronics.

Ge(1-x-y)Si(x)Sn(y) alloys have emerged as a new class of highly versatile IR semiconductors offering the potential for independent variation of band structure and lattice dimension, making them the first practical group IV ternary system fully compatible with Si CMOS processing. In this paper we develop and apply new synthetic protocols based on designer molecular hydrides of Si, Ge, and Sn to demonstrate this concept from a synthesis perspective. Variation of the Si/Sn ratio in the ternary leads to an entirely new family of semiconductors exhibiting tunable direct band gaps (E(o)) ranging from 0.

ClnH6-nSiGe compounds for CMOS compatible semiconductor applications: synthesis and fundamental studies.

We describe the synthesis of a new family of chlorinated Si-Ge hydrides based on the formula ClnH6-nSiGe. Selectively controlled chlorination of H3SiGeH3 is provided by reactions with BCl3 to produce ClH2SiGeH3 (1) and Cl2HSiGeH3 (2). This represents a viable single-step route to the target compounds in commercial yields for semiconductor applications.

Redetermination of tetra-kis(trimethyl-stann-yl)germane.

Redetermination of the structure of the title compound, [Ge(SnMe(3))(4)] or [GeSn(4)(CH(3))(12)], previously refined from powder diffraction data only [Dinnebier, Bernatowicz, Helluy, Sebald, Wunschel, Fitch & van Smaalen et al. (2002 ▶). Acta Cryst.

Synthesis of butane-like SiGe hydrides: enabling precursors for CVD of Ge-rich semiconductors.

The synthesis of butane-like (GeH(3))(2)(SiH(2))(2) (1), (GeH(3))(2)SiH(SiH(3)) (2), and (GeH(3))(2)(SiH(2)GeH(2)) (3) Si-Ge hydrides with applications in low-temperature synthesis of Ge-rich Si(1-x)Ge(x) optoelectronic alloys has been demonstrated. The compositional, vibrational, structural, and thermochemical properties of these compounds were studied by FTIR, multinuclear NMR, mass spectrometry, Rutherford backscattering, and density functional theory (DFT) simulations. The analyses indicate that the linear (GeH(3))(2)(SiH(2))(2) (1) and (GeH(3))(2)(SiH(2)GeH(2)) (3) compounds exist as a mixture of the classic normal (n) and gauche (g) conformational isomers which do not seem to interconvert at 22 degrees C.

Synthesis and fundamental studies of (H3Ge)xSiH4-x molecules: precursors to semiconductor hetero- and nanostructures on Si.

The synthesis of the entire silyl-germyl sequence of molecules (H(3)Ge)(x)SiH(4)(-)(x) (x = 1-4) has been demonstrated. These include the previously unknown (H(3)Ge)(2)SiH(2), (H(3)Ge)(3)SiH, and (H(3)Ge)(4)Si species as well as the H(3)GeSiH(3) analogue which is obtained in practical high-purity yields as a viable alternative to disilane and digermane for semiconductor applications. The molecules are characterized by FTIR, multinuclear NMR, mass spectrometry, and Rutherford backscattering.