F:Flammable;7440-56-4Relevant academic research and scientific papers
Low temperature growth of single crystalline germanium nanowires
Pei,Zhao,Tan,Yu,Chen,Wang,Fan,Chen,Zhang, Qian-Feng
, p. 153 - 158 (2010)
Ge nanowires have been prepared at a low temperature by a simple hydrothermal deposition process using Ge and GeO2 powders as the starting materials. These as-prepared Ge nanowires are single crystalline with the diameter ranging from 150 nm to 600 nm and length of several dozens of micrometers. The photoluminescence spectrum under excitation at 330 nm shows a strong blue light emission at 441 nm. The results of the pressure and GeO2 content dependences on the formation and growth of Ge nanowires show that the hydrothermal pressure and GeO2 content play an essential role on the formation and growth of Ge nanowires under hydrothermal deposition conditions. The growth of Ge nanowires is proposed as a solid state growth mechanism.
High quality Ge on Si by epitaxial necking
Langdo,Leitz,Currie,Fitzgerald,Lochtefeld,Antoniadis
, p. 3700 - 3702 (2000)
We show that pure Ge grown selectively on SiO2/Si substrates in 100 nm holes is highly perfect at the top surface compared to conventional Ge lattice-mismatched growth on planar Si substrates. This result is achieved through a combination of interferometric lithography SiO2/Si substrate patterning and ultrahigh vacuum chemical vapor deposition Ge selective epitaxial growth. This epitaxial necking, in which threading dislocations are blocked at oxide sidewalls, shows promise for dislocation filtering and the fabrication of low-defect density Ge on Si. Defects at the Ge film surface only arise at the merging of epitaxial lateral overgrowth fronts from neighboring holes. These results confirm that epitaxial necking can be used to reduce threading dislocation density in lattice-mismatched systems.
Synthesis of crystalline and amorphous germanium nanorods
Wu, Xingcai,Tao, Yourong
, p. 2179 - 2183 (2002)
Crystalline and amorphous germanium nanorods have been synthesized by PVD of germanium powders in flowing Ar/H2 atmospheres. TEM images show diameters of the nanorods ranging from 20 to 200 nm and length up to 5 μm. Selected area electron diffraction indicates that the crystalline nanorods have tetragonal structure. Their growth process has been considered as VLS mechanism. Published by Elsevier Science Ltd.
SiF4-Sensitized Decomposition of GeH4 by a Pulsed CO2 TEA Laser1,2
Blazejowski, J.,Lampe, F. W.
, p. 8038 - 8045 (1989)
The decomposition of GeH4, sensitized by multiphoton absorption of unfocused infrared laser radiation by SiF4, has been studied in the fluence range 0.2-0.9 J/cm2 and over a total pressure range of 1-70 Torr.Strong absorption of energy from a pulser CO2 laser photon field (P40 line; 1027.4 cm-1) and subsequent energy-transfer processes cause an increase in the temperature of the system.As a result of these processes, decomposition of GeH4 occurs leading to the formation of stoichiometric amounts of metallic germanium and molecular hydrogen.The effects of initial composition, pressure, fluence, and presence of foreign gases (He, H2) on the yield of GeH4 decomposition were examined.A reaction model is proposed which assumes that molecules initially present in the absorption volume are heated by the laser pulse and subsequently decompose unimolecularly.Since the decomposition process is exothermic, it prompts a futher increase in temperature and thus enhances the decomposition process.Both absorption and decomposition create a shock wave causing expansion of hot gas into cool surrounding volume.The latter process brings about cooling of the hot gas and quenches the decomposition process.Taking into account the above-mentioned effects the temperature profiles (T versus time and geometry of the reaction zone) were evaluated on the basis of statistical thermodynamics, assuming that, at any stage, the system attains thermal equilibrium.Yields of decomposition were then derived with kuni values calculated by the RRKM method.The proposed approach accounts satisfactorily for the experimentally observed dependencies, and we believe it can be generally applied to the description of photosensitized process in the infrared region.
Benchtop electrochemical liquid-liquid-solid growth of nanostructured crystalline germanium
Carim, Azhar I.,Collins, Sean M.,Foley, Justin M.,Maldonado, Stephen
, p. 13292 - 13295 (2011)
An electrochemical liquid-liquid-solid (ec-LLS) process that produces large amounts of crystalline semiconductors with tunable nanostructured shapes without any physical or chemical templating agent is presented. Electrodeposition of Ge from GeO2(aq) solutions followed by dissolution into a liquid Hg electrode, saturation of the liquid alloy, and precipitation can yield polycrystalline Ge(s) under ambient conditions. A unique advantage of ec-LLS is that it involves precipitation under electrochemical control, where the applied bias precisely defines the flux of Ge into the liquid electrode. Fidelity of the saturation and precipitation of Ge from liquid electrodes affords a variety of material morphologies, including dense films of oriented nanostructured filaments with large aspect ratios (>103). Electrodeposition involving a liquid electrolyte, a liquid electrode, and a solid deposit under ambient conditions represents a conceptually unexplored direct wet-chemical route for the preparation of bulk quantities of crystalline group-IV semiconductors without the time- and energy-intensive processing steps required in traditional preparations of semiconductor materials.
On direct-writing methods for electrically contacting GaAs and Ge nanowire devices
Chen, Guannan,Gallo, Eric M.,Burger, Joan,Nabet, Bahram,Cola, Adriano,Prete, Paola,Lovergine, Nico,Spanier, Jonathan E.
, (2010)
The electronic transport and gating characteristics in GaAs and Ge nanowires (NWs) are altered significantly following either indirect or direct exposure to a focused Ga+ ion beam (FIB), such as that used to produce Pt electrical contacts to NWs. While these results challenge the assumptions made in some previously reported work relating to the electronic properties of semiconductor NWs using FIB-assisted production of contacts and/or their leads, local electron beam induced deposition is shown to be a reliable and facile route for producing robust electrical contacts to individual vapor phase-grown NWs in a manner that enables study of their actual carrier transport properties.
Formation of nickel germanide contacts to Ge nanowires
Dellas,Minassian,Redwing,Mohney
, (2010)
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 observ
Influence of defects and interface on radiative transition of Ge
Jan,Chen,Lee,Chan,Peng,Liu,Yamamoto,Tillack
, (2011)
The influences of defects and surface roughness on the indirect bandgap radiative transition of Ge were studied. Bulk Ge has 15 times the integrated intensity of photoluminescence of Ge-on-Si. However, for Ge-on-Si sample, the direct transition related ph
Application of n-dodecyltrimethylammonium chloride for the oxidation of intermetallic phases
Boehme, Bodo,Hoffmann, Stefan,Baitinger, Michael,Grin, Yuri
, p. 230 - 238 (2011)
The thermal decomposition products of ionic liquids based on n-dodecyltrimethylammonium chloride (DTAC) were used for the preparation of the metastable allotrope Ge(cF136) by oxidation of Na12Ge17 in gas-solid reactions. This method of preparation provides a promising low-temperature route for the synthesis of intermetallic phases and elemental modifications. In order to explore the reaction mechanism, we investigated the thermal decomposition of DTAC as well as of the ionic liquids DTAC/MgCl 2 and DTAC/AlCl3 by in-situ mass spectrometry and by powder X-ray diffraction. The results have revealed HCl, CH3Cl and 1-chlorododecane to act as oxidizing agents in the gas-solid redox reactions.
Influence of HCl on the chemical vapor deposition and etching of Ge islands on Si(001)
Kamins,Briggs,Williams, R. Stanley
, p. 1862 - 1864 (1998)
When HCl is added during the growth of Ge islands on Si(001) by chemical vapor deposition, the reduced Ge surface diffusion impedes island development. There is a shift in the relative populations of different island types even when other conditions such as temperature, coverage, and growth rate, are unchanged. The effect of HCl on the net rate of deposition is proportional to the square of the HCl partial pressure, suggesting a surface reaction with the Ge. When larger islands are etched with HCl at high enough temperature, they revert to a shape characteristic of smaller islands, confirming the reversibility of transformations from one island type to another. It has not proved possible to use etching to produce smaller and more uniform islands.
