Channeling of protons,pions and deuterons in the GeV region

Strong directional effects have been observed when 1.15 and 1.35 GeV/c protons, π⁺ and π^?, and deuterons penetrate through germanium crystals. Transmission, wide-angle scattering, and an attempt to do blocking distributions are obtained from experiments using position-sensitive drift chambers. Corresponding measurements of energy loss in germanium crystals are also presented. These experimental results are compared to theory for energy loss, and satisfactory agreement is obtained.     

Density-dependent luminescence properties of the electron-hole liquid in highly excited germanium

Luminescence from electron-hole liquid (EHL) has been observed in pure germanium with electron-hole pair densities up to 1.8 × 10¹⁹cm^?3 at 1.6K by use of a high power-pulsed laser. From the fit of the theoretical line shapes, the Fermi energy and ground-state energy of EHL are experimentally obtained as a function of electron-hole pair density.     

Excited Atoms in the Flash Photolysis of some Germanium Compounds

We have recently reported measurements of the rates of the collisional relaxation of various atoms amongst the spin-orbit components of their ground electronic states; an approximate correlation exists with other types of molecular energy transfer.^1-3 We present here an outline of some qualitative observations of the production and relaxation of Ge(4¹D₂) and Ge(4³P_j) in the flash photolysis of a number of germanium compounds. Atomic germanium vas selected for study because the ground state comprises a ‘normal’ Landé multiplet and should exhibit ‘Inverted’ relaxation as compared for example to Fe(a⁵D_j) which equilibrates initially in the high energy substates. The low lying states of germanium are listed In table 1.⁴ The flash photolysis apparatus was of standard design^1-3 and spectra were recorded with a Hilger medium quartz spectrograph.     

Beta decay of 31Ar

A complete study of ³¹Ar beta decay has been made by high-resolution charged-particle and gamma-ray spectroscopy. Beta-delayed radiation was detected by an array of three charged-particle detectors and a large-volume germanium detector. Fifteen new energy levels were discovered in ³¹Cl. The beta-strength distribution, measured to 14.5 MeV, is compared with a shell-model calculation in the full sd space. The quenching of the Gamow-Teller strength and the isospin impurity of the IAS in ³¹Cl are discussed.     

Determination of the mid-IR femtosecond surface-damage threshold of germanium

To assess the potential uses of germanium as a nonlinear material in the mid IR we have measured the surface-damage threshold of germanium optical windows using femtosecond pulses at a wavelength of 3.9 μm. By working with a wavelength corresponding to a photon energy of less than half the band-gap energy, free-carrier generation due to one- and two-photon absorption was eliminated. The laser pulses had an energy of 5.5 μJ, a duration of 255 fs, and were focused to a waist size of approximately 100 μm. The multi-shot damage threshold of the germanium windows was estimated to be approximately 94 GW/cm². The data should be of immediate benefit to industrial laser researchers and applications engineers working in the mid-IR region.     

The first spectroscopic observation of germanium carbide

The gas phase spectrum of the germanium carbide radical has been observed at low temperature in emission from a corona excited supersonic expansion source. Many vibrational bands involving the Ω = 0, 1, and 2 components of the (2)³Π–X³Π system were recorded and analyzed. The equilibrium transition energy is found at 21120.3 cm⁻¹, in good agreement with theoretical predictions. The fundamental vibrational frequency for the lowest energy ground state Ω = 2 component is 795.3 cm⁻¹.     

Lattice disorder in germanium by boron ion bombardment

Abstract

The lattice disorder produced in germanium by 56keV boron-ion bombardment has been measured using the channeling-effect technique. The dependence on dose (10¹⁴-10¹⁶ ions/cm²) and implantation temperature (?90 °C to +130°C) has been studied. It is found that at room-temperature, each incident boron ion creates ?10 times more disorder in germanium than in silicon. It is remarked that, contrary to the present results, previously established anneal stages generally occur at significantly lower temperatures in germanium than in silicon.     

X-ray photoelectron and auger spectroscopy analysis of Ge:Mn-based magnetic semiconductor layers

Thin (～60 nm) germanium layers supersaturated with a manganese impurity of 10–16 at % have been studied by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The layers have been fabricated by pulsed laser deposition onto a semi-insulating single-crystal GaAs substrate. The results of XPS analysis of the Ge:Mn layers reveal a change in the line shape of germanium and manganese (2p) in the surface region compared to deeper layers, which indicates a transition from the oxidized form of the base material (Ge²⁺ and Ge¹⁺) and impurity (Mn²⁺) near the surface to the unoxidized state of germanium (Ge ⁰) and manganese (Mn⁰) in the interior of the layer. The XPS spectra of the valence electrons of the Ge:Mn structure indicate that the density of states in the valence band of the ferromagnetic Ge:Mn structures is caused not only by mechanical mixing of germanium and manganese. The composition of heterogeneous inclusions in Ge:Mn films has been studied using scanning Auger microscopy.     

Low-temperature diffusion of gold in germanium under the influence of atomic hydrogen

An investigation is made of the diffusion of gold in germanium under the influence of the energy released by the recombination of hydrogen atoms to form molecules. Crystals of n-type germanium with gold films (d=1×10⁻⁷ m) are exposed to atomic hydrogen for various times (up to 10⁴ s) at temperatures close to room temperature. The diffusion of gold in the germanium is analyzed by laser mass spectrometry, and also by measuring the surface resistance, the minority carrier lifetime, and the infrared transmission spectra. Mechanisms are proposed for the stimulation of heterodiffusion and accompanying processes. Zh. Tekh. Fiz. 69, 73–76 (July 1999)     

Dechanneling of MeV protons in tungsten

Abstract

A systematic investigation of the dechanneling of protons in tungsten has been completed for the <111> axial direction and also for the (110) plane. Measurements at room temperature have been made at energies of 0.5, 2.0, 3.5, 8.0 and 12.0 MeV; at 2.0 MeV, the effect of target temperature has been investigated over the range 77–873°K. In the axial case, the dechanneling rate increases strongly with the vibrational amplitude _ρ, but not as strongly as the ρ² dependence reported by the Catania group (Refs. 4–7) for silicon and germanium. Also, unlike silicon and germanium, the tungsten axial data exhibit practically no energy dependence and so cannot be fitted by the zρ²/E scaling parameter suggested by the Catania group. On the other hand, the planar dechanneling data in tungsten exhibit the predicted (E ^?1)dependence and relatively littie temperature dependence, in good agreement with previous work.     

Beiträge zu den Niveauschemata der Ge-Isotope71Ge,73Ge,74Ge und75Ge aus der Untersuchung von (n, γ)-Reaktionen in natürlichem Germanium

Low energy γ-spectra from neutron capture in natural germanium have been studied with several high resolution Ge(Li)-detectors. Measurements have been made with two different target configurations. In the first measurement a normal Ge-target was irradiated with neutrons; no neutrons were allowed to enter the Ge(Li)-detector. In the second measurement the Ge(Li)-detector was used simultaneously as target and as γ- ande ^?-detector. By combination of the results convertion coefficients of several transitions in⁷³Ge have been determined. Several unknown low energy transitions in Ge isotopes have been found with the aid of the second method. The level schemes of⁷¹Ge,⁷³Ge,⁷⁴Ge and⁷⁵Ge have been revised by means of coincidence measurements with a Ge(Li)-Ge(Li)-coincidence system of high efficiency and resolution.     

Gammaübergänge und Energieniveaus im49V aus der Reaktion48Ti(p, γ)49V

Deexcitation gamma rays of⁴⁹V from the⁴⁸Ti (p, γ)⁴⁹V reaction have been investigated at the resonancesE _p=1007, 1209, 1362 and 1374 keV corresponding to excited states in⁴⁹V at 7742, 7940, 8090, 8102 keV. A 4 cm²× 0.35 cm lithium-drifted germanium detector was used. The target was TiO₂ enriched in⁴⁸Ti to 99.4%. 71 gamma transitions have been observed. A level scheme of⁴⁹V is proposed involving 8 new levels in the energy range from 0 to 5.2 MeV excitation energy.     

Profiles of transmutation-produced isotopes in proton-and helium-irradiated germanium

Profiles of radioactive isotopes produced in nuclear reactions in germanium irradiated by protons or ⁴He nuclei were studied. The profiles were used to determine the energy dependence of the cross sections of nuclear reactions producing transmutation isotopes.     

半导体中浅杂质的傅里叶变换光热电离光谱

本文报道与快扫描傅里叶变换红外光谱仪相结合的光热电离光谱实验装置和测量系统。采用该系统高分辨率、高灵敏度地研究和测量高纯锗和高纯硅中的剩余浅杂质获得成功。在P型超纯Ge中发现浓度低达10⁸cm^-3的硼受主杂质的光热电离谱线,而探测灵敏度则至少可达10⁷cm^-3;在n型高纯Si中观测到Li-O复合型浅施主中心D(Li,O);施加本征激发光后在P型高纯Si中同时观察到B受主和P施主的跃迁谱线系。此外,在Si,Ge中均观察到 关键词：     

Observation of an enhanced gettering effect in silicon under germanium molecular ion implantation

Germanium atomic (Ge₁ ⁺) and molecular ions (Ge₂ ⁺) of equal energy per atom are implanted in silicon at an elevated temperature. The ion induced damage has been monitored by following the intensity variation of the LO Raman peak of Si. The germanium implanted samples have been labeled with 10 keV Au ions. The gettering of gold has been observed by Rutherford backscattering spectrometry in the post-annealed samples. This paper reports a first time observation of an enhanced gettering of gold in silicon implanted with molecular ions. PACS 61.72.Ji; 61.80.Lj; 61.80.Jh; 61.72.Yx     

Photorecombination of Ar-like gallium and germanium ions

The most up-to-date photorecombination spectrum of Ga¹³⁺ and Ge¹⁴⁺ has been re-assessed with direct large-scale relativistic atomic structure calculations. The new temperature-dependent dielectronic recombination rate coefficients are presented in a form convenient for astrophysical plasma modeling, summarizing the importance of different multi-electron intra-shell core excitations in the target ions. Obtained results are expected to facilitate a more accurate determination of the ionization-recombination balance of multiply-charged gallium and germanium ions and to improve the diagnosis of the radiative energy loss rates from low-density high-temperature plasmas.     

Irradiation-induced compensation of n-type germanium: An optical study of vibrational absorption

n-type germanium crystals doped with As, Sb, P, P + In, P + Ga or As + B have been rendered transparent by high energy e^? or n⁰ irradiation. Localized vibrations of P, [P-In], [P-Ga], B and [B-As] have been observed. It is concluded that the compensation process must occur predominantly by the introduction of defects which act as acceptors and which do not involve the shallow donor impurity atom.     

Neutron interactions as seen by a segmented germanium detector

The GERmanium Detector Array (GERDA) is designed for the search for “neutrinoless double-beta decay” ( 0ν2β with germanium detectors enriched in ⁷⁶Ge . An 18-fold-segmented prototype detector for GERDA Phase II was exposed to an AmBe neutron source to improve the understanding of neutron-induced backgrounds. Neutron interactions with the germanium isotopes themselves and in the surrounding materials were studied. Segment information is used to identify neutron-induced peaks in the recorded energy spectra. The Geant4-based simulation package MaGe is used to simulate the experiment. Though many photon peaks from germanium isotopes excited by neutrons are correctly described by Geant4, some physics processes were identified as being incorrectly treated or even missing.     

Far-infrared magneto-absorption of donor-bound excitons in germanium: Pseudo-acceptor model

The magneto-oscillatory absorption spectrum of the arsenic-bound excitons in germanium observed at 118.6 μm reveals a series of absorption lines similar to the Zeeman spectrum of the acceptor impurity. This fact indicates that the bound excitons have the excited states associated with the light-hole Landau ladders and these excited states can be described by the model of a hole bound to the D^- state, i.e. the pseudo-acceptor model. The hole binding energy of the ground state of the bound excitons has been obtained to be 4.7 meV, which is smaller compared with the binding energy of the acceptor impurity.     

TheK-shell fluorescence yield of germanium

TheK-shell fluorescence yield of germanium has been determined asω _K=0.570±0.003 by the modified proportional counter technique using a special wall-less proportional counter filled with methane and small admixture of germanium hydride GeH₄. The required ratio of the total photoabsorption to the absorption in theK-shell has been obtained from the separate study of the energy dependence of the X-ray absorption in germanium.