Oxygen In Germanium Research Articles

Photochemical reactions of germoxanes: Generation of germyl and germoxy radicals

Photochemical reactions of phenyl-substituted digermoxanes, (Ph n Me 3- n Ge) 2O ( n = 1–3), and a cyclic germoxane, (Me 2GeO) 4, have been investigated by chemical trapping and laser flash-photolysis. On irradiation, phenylated digermoxanes undergo homolysis of the germanium—oxygen bond to give germyl radicals and germoxy radicals. In the presence of nonhalogenated solvents, these germyl radicals and gerrnoxy radicals couple to yield digermanes and digermyl peroxides, respectively. In polyhalomethanes (CCl 4, CHCl 3, and BrCCl 3), germyl radicals are converted to the corresponding halides by abstraction of a halogen atom. Germoxy radicals do not react with polyhalomethanes; they couple to produce digermyl peroxides which decompose to give either a pair of germoxy radicals or germyl radicals and germylperoxy radicals. Photolysis of a cyclic germoxane also results in cleavage of the germanim—oxygen bond.

Geometrical configuration of interstitial oxygen in silicon and in germanium

First principles calculations have been performed to establish the geometrical configuration of interstitial oxygen in crystalline silicon and germanium. The calculations are performed in finite but representative clusters of atoms. The results of the calculations confirm early indications of the puckered character of both Si-O-Si and Ge-O-Ge bonds. The Si-O-Si bond angle is found to be 153° whereas the calculated Ge-O-Ge bond angle is 132°.

Spectroscopy of defects in germanium-doped silica glass

We present data concerning the dynamics of photoexcitation of defect centers in germanium-doped silica glass optical fibers and fiber preforms. It is shown that two-photon absorption of mode-locked and Q-switched light at 527 nm results in partial ionization of the germanium oxygen deficiency center (GODC) 400-nm luminescence band. This bleaching induces loss in the 320–600-nm wavelength range, which we argue is due to the introduction of Ge(1) centers and charges trapped at structural defects in the glass. The excitation and relaxation of dynamics of the GODC are analyzed by examining the photoluminescence and absorption spectra, and two models are proposed to explain the observed behavior.

Phonon spectroscopy of the low energy vibrations of interstitial oxygen in germanium

In oxygen doped Ge we find by phonon spectroscopy with superconducting tunnelling junctions a series of lines between 0.18 meV and 4.08 meV which can be interpreted as due to low lying states of the interstitial oxygen (O i ) as a rigid rotator around a 〈111〉-axis slightly perturbed by the lattice potential. The sequence of transitions can be fit assuming a binding angle of (106 ± 1)° which is much smaller than the value of (162 ± 1)° for O i in Si. Line shifts and splittings with uniaxial stress along 〈100〉, 〈110〉, and 〈111〉 are in qualitative agreement with this interpretation.

Interstitial Oxygen in Nature and Monoisotopic Germanium

Interstitial Oxygen in Nature and Monoisotopic Germanium

Electronic properties of hydrogen-related complexes in pure semiconductors

Hydrogen has been shown to activate the neutral impurities carbon, silicon and oxygen in ultra-pure germanium and form shallow level complexes. The double acceptors beryllium and zinc in silicon and germanium, as well as the triple acceptor copper in germanium, can be partially passivated, leading to single hole acceptors. The study of the electronic level spectrum of the single carrier bound to these centers at low temperatures has provided much information on symmetry and composition. Most centers reveal a symmetry axis along [1 1 1] and are static. In some cases hydrogen has been found to tunnel between equivalent real space positions. Photothermal ionization spectroscopy (PTIS) has been the most important tool for the study of the optical transitions of the hole (electron) in these hydrogen containing complexes. This photoconductivity technique combines high sensitivity with high resolution and permits the study of shallow acceptors or donors present at concentrations as low as 108 cm-3. Even lower limits may be attained under favorable circumstances.

A SIMS-XPS study on silicon and germanium under O +2 bombardment

Using a combined SIMS-XPS system it is shown that the much lower secondary ion yield of Ge + sputtered from germanium under 10 keV O + 2 bombardment at normal incidence compared to the Si + yield sputtered from silicon is due to the much smaller uptake of oxygen in germanium vs silicon. Data are also presented on the chemistry induced in b oth elements as a function of the angle of incidence of the O + 2 beam.

The Measurement of Low Levels of Oxygen in Germanium by the Lithium Precipitation Technique

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Activities of oxygen in liquid Bi, Sn, and Ge from electrochemical measurements

Modified coulometric titrations on the galvanic cell: O in liquid Bi, Sn or Ge/ZrO2( + CaO)/Air, Pt, were performed to determine the oxygen activities in liquid bismuth and tin at 973, 1073 and 1173 and in liquid germanium at 1233 and 1373 K. The standard Gibbs energy of solution of oxygen in liquid bismuth, tin and germanium for 1/2 O2 (1 atm) →O (1 at. pct) were determined respectively to be ΔG° (in Bi) = −24450 + 3.42T (±200), cal· g-atom−1 = − 102310 + 14.29T (±900), J·g-atom−1, ΔG° (in Sn) = −42140 + 4.90T (±350), cal· g-aton−1 = −176300 + 20.52T (± 1500), J-g-atom−1, ΔG° (inGe) = −42310 + 5.31 7 (±300), cal·g-atom−1 = −177020 + 22.21T(± 1300), J· g-atom−1, where the reference state for dissolved oxygen was an infinitely dilute solution. It was reconfirmed that the modified coulometric titration method proposed previously by two of the present authors produced far more reliable results than those reported by other investigators.

INFRARED ABSORPTION OF OXYGEN IN SILICON AND GERMANIUM AT LOW TEMPERATURES

Infrared Absorption measurements of oxygen in silicon and germanium were made with IE Fourier Transform Spectrometer at temperatures between 6 K and 300 K in the region of 400-4000cm-1. Resolution was up to 0.5cm-1 when high resolution conditions were adopted.Detection limit and sources of error on oxygen concentration of silicon and germanium determined by infrared absorption measurement at low temperature were identified. Using a 2 cm thick sample, the- lower limit of detectability for oxygen at 20 K is estimated to be 9.6×1014 oxygen atom. cm-3 and 3.0×1014 oxygen atom. cm-3 in silicon and germanium respectively. The oxygen concentration of CZ germanium single crystals with different growth conditions was also studied and these results determined by IE measurements havebeen investigated and discussed at temper-lithium precipitation technique.Temperature-dependent fine structure of 1106 cm-3 absorption band of silicon with different oxygen concentration have been investigated and discussed at temper atures between 6 K and 300 K.

Stability of Oxides in High Purity Germanium

The thermochemical approach to reactions between dilute solutes is presented and applied to the stability of oxide second phases in the high purity germanium melt. Such oxide phases may degrade detector resolution and complicate purification. The equilibrium of oxygen between melt and gas allows both a convenient indication of the chemical potential of oxygen in the melt and a straightforward thermochemical calculation of reactions involving oxygen. For the range of oxygen (1013 - 1014 cm-3) and other impurity concentrations in high purity germanium no tabulated oxide is expected to be stable in the melt. If the concentration of oxygen in the melt is increased, the first important oxide phase to become stable is SiO2(1), strongly enriched with aluminum.

Formation et caracterisation de germanones R 2Ge=O a partir d'heterocycles germanies

The thermolysis of germanium oxetanes and adducts of germanium- dioxolanes, oxazolidines and diazolidines with carbonyl compunds leads to transient dialkylgemanones R 2Ge=O characterized by addition of alkoxy- gemanes and oxagermacyclopentanes on the germanium—oxygen bond, and by insertion and ring expansion reactions with ethylene oxide, with formation of germadioxolanes.

Solubility and activity of oxygen in liquid germanium and germanium-copper alloys

Solubility and activity of oxygen in liquid germanium and germanium-copper alloys

Solubility and activity of oxygen in liquid germanium and germanium-copper alloys

The solubility of oxygen in liquid germanium in the temperature range 1233 to 1397 K, and in liquid germanium-copper alloys at 1373 K, in equilibrium with GeO2 has been measured by the phase equilibration technique. The solubility of oxygen in pure germanium is given by the relation log(at. pct 0)=-6470/T + 4.24 (±0.07). The standard free energy of solution of oxygen in liquid germanium is calculated from the saturation solubility, and recently measured values for the free energy of formation of GeO2, assuming that oxygen obeys Sievert’s law up to the saturation limit. For the reaction, 1/2 O2(g)→OGe ΔG° = -39,000 + 3.21T (±500) cal = -163,200 + 13.43T (±2100) J. where the standard state for dissolved oxygen is that which makes the value of activity equal to the concentration (in at. pct), in the limit, as concentration approaches zero. The effect of copper on the activity of oxygen dissolved in liquid germanium is found to be in good agreement with that predicted by a quasichemical model in which each oxygen was assumed to be bonded to four metal atoms and the nearest neighbor metal atoms to an oxygen atom are assumed to lose approximately half of their metallic bonds.

EPR study on amorphous germanium oxygen, deposition angle, annealing, and substrate temperature effects

AbstractThe influence of various deposition parameters, especially oxygen pressure and deposition angle, on the a‐Ge EPR spectra is studied. In most the cases the results corroborate those already obtained by other authors with other methods (such as conductivity). Two different mechanisms are discussed to explain the spin density decrease: saturation of defects by introducing oxygen and decrease of the defect concentration by structural rearrangements with annealing or substrate temperature increase. At suitable annealing conditions a spin density increase suggests the formation of defects such as multivacancies. The comparison of the EPR line thus obtained with the initial one shows that the defects formed during the evaporation of the purest samples are the same. The EPR line is inhomogeneous.

The determination of oxygen in germanium by alphaparticle activation analysis

The determination of trace levels of oxygen in germanium by activation analysis with 45-MeV α-particles is described. The chemical separation of 18F formed from oxygen consists of repeated distillation of fluorosilicic acid followed by precipitation of lead chlorofluorideand allows a reduction of the matrix radiation by a factor of 4 10 6. Oxygen concentrations of about 20 ng g -1 are found for high-purity germanium; for oxygen doped monocrystals, oxygen concentrations of 400 and 700 ng g -1 are found. The influence of surface contamination on the final results is studied.

Reactions d'insertion de fluorogermylenes sur diverses liaisons σ. Nouvelles syntheses de derives polymetalles du groupe IVB

Difluorogermylene which exhibits a strong carbene activity gives many insertion reactions in σ bonds. In the same type of reactions, the lower reactivity of phenylfluorogermylene is generally similar to reactivity of the phenylchlorogermylene. The polymetallated derivatives of Group IVB metals formed by insertion reactions of these germylenes in σ bonds, like metalhalogen, metalhydrogen, metaloxygen, metalsulfur, metalnitrogen and metalmetal bonds, have low stability and thermally decompose via α-elimination processes to form germylenes and fluoro-organometallics. The polymetallated derivatives have been characterised by spectroscopy and chemical investigations: alkylation or arylation of their M(IVB)X bonds (X = halogen, oxygen etc.). The insertation reactions of difluoro-, phenylfluoro- and phenylchloro-germylenes into the intracyclic germaniumoxygen bond of diastereoisomeric oxaermacycloalkanes are generally stereospecific and can be interpreted by a concerted mecanism.

Kinetics of Environmental Averaging, and the Stereochemistry of (CH3)ClGe(C5H7O2)2. A Case of a Second Order Kinetic Process

Dynamic n.m.r. studies on the stereochemistry of (CH3)ClGe(C5H7O2)2 (acac = C5H7O2−), indicate that the complex adopts the cis configuration in CDCl3–CCl4 solutions. Kinetics of environmental averaging of the acac ring proton (—CH=) and acac methyl groups between the respective nonequivalent sites in the C1 isomer have been investigated in the temperature range −31.0 to 23.1° by line-broadening techniques. Kinetics of the averaging process are second order in complex concentration. Activation parameters are: Ea = 6.0 ± 0.3 kcal/mol, ΔS≠ = −30 ± 1 e.u., and k25 = 1.6 × 102 M−1 S−1. Rearrangements are viewed as occurring via a germanium–oxygen bond rupture as a first step to yield a five-coordinate intermediate. The rate-determining sequence is thought to involve proper orientation of two five-coordinate species prior to formation of a bis-acac bridged dimer.

Nucleophilic cleavage of the germanium–oxygen bond: acid-catalysed hydrolysis of phenoxygermanes

The acid-catalysed hydrolysis of phenoxygermanes in aqueous dioxan proceeds to a position of equilibrium, and kinetic data show that the reaction is at least second-order with respect to water. Tributylphenoxygermanè reacts 5 × 105 faster than the analogous phenoxysilane. This result is compared with the relative reactivities of other organosilicon and organogermanium compounds.

Localized vibrational modes for implanted oxygen in germanium

The first observation of localized vibrational modes for an implanted ion in Ge is reported. The localized mode for interstitial oxygen at 856 cm−1 and additional weak oxygen-associated absorption bands between 700 and 850 cm−1 have been observed by infrared absorption following oxygen implantation at 200 °C. Infrared detection of the vibrational modes for oxygen implanted into Ge at room temperature is precluded by ion-induced disorder and by absorption presumably associated with free carriers in the implanted layer.