摘要:

The amorphous (a) to microcrystalline (&mgr;c) transition, induced by the increase of the ion bombardment energyEionand the substrate temperatureTs, is investigated on glow‐discharge deposited germanium thin films. This transition and the deposition of &mgr;c‐Ge on metallic substrates are observedinsituby kinetic and spectroscopic phase modulated ellipsometry (SPME) over the range 1.7–4.5 eV. The ion bombardment energy corresponding to the transitiona‐&mgr;c (Eion∼120 eV) decreases as a function ofTsin the range 160–280 °C. DecreasingEion(orTs) results in the reverse transition. The &mgr;c‐atransition is found at a ∼50 eV (or ∼120 °C) lower value, giving evidence of an epitaxial growth effect. The kinetics of the growth processes is deduced from the SPME data by using an effective medium approximation. The early stage of the growth is accurately described by the nucleation of microcrystalline islands at a 50 A˚ level; the time dependence being coherent with a low surface mobility of the diffusing species. During the growth, a composition depth profile is observed; the ∼150 A˚ thick surface layer being more amorphous than the bulk.

ISSN:0021-8979    

DOI:10.1063/1.341447

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The present paper gives a comprehensive examination of equations and charts for shock waves in water. The Tait equation of state is used in the analysis to describe the compressibility of water. The results for an oblique shock wave are presented in the hodograph plane where all possible velocity vectors downstream of the shock wave are seen to lay on a single curve (i.e., shock polar). The equation of the shock polar and the corresponding charts up to upstream Mach number of 3 are given, as well as a more convenient way of adapting the shock polar. The oblique shock‐wave detachment condition and the sonic flow condition downstream of a shock are also presented.

ISSN:0021-8979    

DOI:10.1063/1.341448

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The room‐temperature thermal conductivity of III‐V compounds is analyzed. The phenomenological approach of Abeles is applied to take into account disordered structure of ternary and quaternary alloys. The procedure is used for the In1−xGaxAsyP1−yquaternary alloy. The approximate analytical expression for this case is derived. A more exact method of the calculations is also proposed. It enables presenting the thermal conductivity and the thermal diffusivity for both the InP lattice‐matched and GaAs lattice‐matched In1−xGaxAsyP1−yalloys as a function of their composition.

ISSN:0021-8979    

DOI:10.1063/1.341449

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Experimental data are presented for the diffusion of arsenic in polycrystalline silicon (polysilicon) during a 15‐min anneal at 900 °C. A new model is used to describe the data, which takes account of the different dopant diffusion rates in grains and in grain boundaries. The model is divided into early and late stages and, in particular, the early stage model identifies grain growth as the major mechanism by which arsenic transfers from the grains to the grain boundaries. In the late stage model, grain growth can be ignored and analytic solutions for the arsenic concentration are derived.

ISSN:0021-8979    

DOI:10.1063/1.341450

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The interfacial reaction between thin Ni film (deposited by eitherebeam evaporation or sputtering) and (Cd, Hg0.8Cd0.2)Te has been investigated using transmission electron microscopy and diffraction. Auger depth profiles have been used to determine the distribution of Te, Cd, Hg, and Ni with respect to the interface of Ni‐Hg1−xCdxTe. In the Ni‐Hg0.8Cd0.2Te system, we observed the &dgr;‐phase (NiTe‐NiTe2) formation upon deposition of 40‐ and 80‐A˚ Ni films with either deposition system at the as‐deposited temperature. The electron diffraction patterns of the &dgr; phase and some Ni were observed, with the formation of the &dgr; phase located at the interface. The electron diffraction of both the Ni film and &dgr; phase were partially ordered with respect to the substrates. The Auger depth profile indicated that the excess of Te appeared mostly at the interface. Annealing of the Ni‐Hg0.8Cd0.2Te system in a vacuum and at 100, 200, and 300 °C shows growth of the crystal and increased ordering of the &dgr; phase. In the Ni‐CdTe system the generation of Te was observed for both sputter deposition andebeam evaporation. Auger profiling indicated that the amount of Te generated by sputtering was approximately three times the amount of Te generated byebeam evaporation. The generated Te was mostly accumulated at the interface of Ni‐CdTe. We observed &dgr;‐phase formation upon annealing at 250 °C after sputter deposition, and at 300 °C afterebeam evaporation of Ni on CdTe substrates, but the crystallites did not have the orientational relation with CdTe substrates (texturing), as was seen in the Ni‐Hg0.8Cd0.2Te system.

ISSN:0021-8979    

DOI:10.1063/1.341459

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The interfacial reaction between thermally oxidized In1−xGaxAsyP1−yand an In1−xGaxAsyP1−yepilayer was studied using Raman and x‐ray photoelectron spectroscopy (XPS) analyses. In Raman spectra, it was found that the appearance of the phonon modes, i.e., the first‐order longitudinal (LO) and transverse‐optical (TO) modes for crystalline arsenic, was due to the In1−xGaxAsyP1−y‐oxide interfacial reaction. The XPS analyses showed that this reaction corresponded to the GaAs‐oxide interfacial reaction, i.e., As2O3+2GaAs→Ga2O3+4As. Furthermore, the reaction depends on the compositionyof In1−xGaxAsyP1−y, which may be due to the enhancement in the initial transient reaction by thermal damage of In1−xGaxAsyP1−yoccurring at the interface.

ISSN:0021-8979    

DOI:10.1063/1.341460

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The surface of freshly deposited hydrogenated amorphous silicon (a‐Si:H)films are studied by argon sputtering and mass‐spectrometer detection of the sputtered neutral molecules. The surface density of H atoms in the top H‐rich layers of the film is established from the initial surge of sputtered H‐containing molecules. This shows that the growing film has a hydrogen‐rich surface layer of multiply H bonded Si atoms about five monolayers thick on a room‐temperature substrate. At the ∼240 °C substrate temperature typical of film production, the thickness of this hydrogen‐rich layer decreases to about one monolayer.

ISSN:0021-8979    

DOI:10.1063/1.341461

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The temperature‐dependent behavior of the solid compositionxsof AlxGa1−xAs has systematically been studied as a function of gas phase compositionxgin an optimized horizontal metalorganic vapor phase epitaxy reactor at atmospheric pressure. Up to a temperature of 660 °C the Al incorporation is constant but slightly exceeds the Ga incorporation. Above this temperature the Al incorporation strongly increases with temperature. This behavior is most probably related to a change in growth mechanism from mass transport limited growth to a regime where the growth is controlled by thermodynamics, especially for the gallium species.

ISSN:0021-8979    

DOI:10.1063/1.341462

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The optically detected magnetic resonance technique is applied to determine the nature of broad, featureless emission bands observed in the near‐infrared region in bulk GaP crystals grown by the liquid encapsulated Czochralski method. A broad emission band with maximum at ≊8000 A˚ (≊1.55 eV) was consistently observed in undoped and donor‐doped (S, Te, Se, Ge) crystals, and is shown to be due to donor‐acceptor pair (DAP) recombination. The analysis of the optically detected magnetic resonance experiments indicates that shallow donors and deep acceptors are active in the 8000‐A˚ recombination. The identity of the ≊0.7‐eV deep acceptor center active in this DAP transition could not be determined from the experimental results, but a single acceptor complex consisting of a Ga vacancy and two adjacent donors is proposed as a tentative model.

ISSN:0021-8979    

DOI:10.1063/1.342490

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Hydrogen plasma exposure of silicon‐doped Ga1−xAlxAs epilayers withx<0.37 causes a strong reduction of the free‐electron concentration in the layers. Forx<0.29, this effect is accompanied by a simultaneous increase of the electron mobility. This is interpreted, as in GaAs, in terms of a neutralization of the active silicon donors by atomic hydrogen. The neutralization efficiency of the shallow donors increases asxincreases. Forx&bartil;0.25, theD‐Xcenters are very efficiently neutralized by hydrogen and, as a consequence, the conductivity mechanisms after exposure are only governed by the remaining shallow donors. For 0.29<x<0.37, most of theD‐Xcenters are neutralized, but the electron mobility after hydrogenation is reduced.

ISSN:0021-8979    

DOI:10.1063/1.341464

出版商:AIP    

年代:1988

数据来源: AIP