摘要:

For potential infrared detector applications, single‐crystalline InAsBi and InAsSbBi have been grown by atmospheric pressure organometallic vapor‐phase epitaxy. The precursors used were trimethylindium, trimethylantimony, trimethylbismuth, and arsine at growth temperatures of 375 and 400 °C. Good quality epilayers with smooth surface morphologies were obtained by properly controlling the key growth parameter, the V/III ratio. The variation of lattice constant with solid composition for the InAs1−xBixsystem,a=6.058+0.966x, provides evidence that Bi atoms indeed incorporate substitutionally into the As sites of the sublattice in the InAs zinc‐blende structure. An extrapolated lattice parameter for the hypothetical zinc‐blende InBi is 7.024 A˚. Thermodynamic calculations of the InAs‐InBi and InSb‐InBi pseudobinary phase diagrams were carried out using the delta‐lattice‐parameter model using the lattice constant for zinc‐blende InBi of 7.024 A˚. The results agree well with experimental data. The calculations predict that the solid solubility limit of Bi in InAs is less than 0.025 at. %. The calculated maximum solubility limit is 2.1 at. % for Bi in InSb at the eutectic temperature of 132 °C. Thus, tremendously large miscibility gaps exist in both alloy systems. The critical temperature was predicted to be 2569 °C for the InAs‐InBi system and 496 °C for the InSb‐InBi system. The miscibility gap is the major factor limiting Bi incorporation into the InAsSb alloys. Nevertheless, metastable InAsBi and InAsSbBi alloys were grown with concentrations far exceeding the solubility limit. For example 3.1 at. % Bi was incorporated into InAs. Infrared photoluminescence measurements show a decrease of peak energy with increasing Bi concentration in the alloys, withdEg/dx=−55 meV/at. %Bi.

ISSN:0021-8979    

DOI:10.1063/1.346166

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

CdTe (111)B layers were grown on oriented and misoriented GaAs (100) substrates by hot‐wall epitaxy. The crystallinity of the layers was examined by x‐ray diffraction. The strain relaxation was investigated by x‐ray diffraction and optical reflectance spectra. (1) For the layers on oriented substrates, it is found that the strain of the layer is relaxed as the layer thickness increases, but additional strain, which is probably due to the formation of twinned domains, remains and is hardly relaxed. (2) Layers on misoriented substrates are twin free with good crystalline quality. Strain is relaxed as the layer thickness increases. The residual strain of layers thicker than 10 &mgr;m is for the most part due to the difference of thermal expansion coefficients between CdTe and GaAs.

ISSN:0021-8979    

DOI:10.1063/1.346167

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effect of &ggr; irradiation on deep electron states in liquid encapsulated Czochralski (LEC) grown GaAs has been investigated by deep‐level transient spectroscopy (DLTS) and photocapacitance measurements. With &ggr; rays of 2×108R, EL6 was reduced in concentration by a factor of 3–5, whereas EL3 was increased about one order of magnitude, as compared with those in as‐grown material. In addition toEtraps that were previously reported in electron‐irradiated material, two new traps were observed near the surface region. From their concentration profiles and annealing behavior, the new traps were most likely created by the interaction of the primary irradiation‐induced defects with the grown‐in defects. In contrast to these results, neither the DLTS spectrum nor the metastable behavior of EL2 was affected by &ggr; irradiation.

ISSN:0021-8979    

DOI:10.1063/1.346168

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A detailed optical study of the metastable III/V semiconductor alloy InP1−xSbxis presented. InP1−xSbxlayers are grown throughout the entire compositional range by atmospheric pressure organometallic vapor phase epitaxy on InP, InAs, and InSb substrates. Composition and strain are measured by combined electron microprobe analysis and x‐ray diffractometry. The dependence of band gap on composition is experimentally established for the first time from absorption spectra measured at 10 and 300 K. The resultant value of the band‐gap bowing parameter is 1.52±0.08 eV, independent of temperature. The absorption spectra show the InP1−xSbxlayers to have long band tails, which extend further into the gap as the Sb concentration is increased. The band tails are induced by compositional clustering. Photoluminescence (PL) spectra are measured between 10 and 300 K. The PL peaks are assigned to recombination between carriers occupying band‐tail states or to recombination via deep centers in the gap.

ISSN:0021-8979    

DOI:10.1063/1.346169

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The study of the variation of the electrical resistivity &rgr; between 10 and 1000 K has been performed in the Co75Si25−xBxand Co100−x(Si0.6B0.4)xferromagnetic amorphous series. A general analysis of the curves gives useful data about the main features of &rgr; in these materials: Curie temperaturesTc, temperatures of the minimaTmin, crystallization temperaturesTx, temperature coefficient of resistivity, and absolute resistivity. The correlations between these magnitudes have been discussed including direct comparison with the nonmagnetic Ni‐Si‐B similar compounds. An analysis of the structural and magnetic contributions to the resistivity is presented in the whole temperature range. The structural part is interpreted in the framework of the extended Ziman model and it is superposed on the magnetic term. AT2magnetic contribution coming from the spin wave scattering is found at temperatures betweenTminand approximately 0.5Tc. At higher temperatures, the magnetic part seems to be understood taking into account the mean field approximation. Saturation magnetizationM(T) measurements over 300 K were carried out in order to get an experimental hint of the correlation between the magnetic &rgr; andM(T) with rather satisfactory results. Besides the general analysis we report the achievement of a progressive shift ofTminin some compounds (in particular in Co70Si18B12) in which a tentative explanation might be based on phonon ineffectiveness arguments.

ISSN:0021-8979    

DOI:10.1063/1.346170

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Current noise in mixed‐ion Na/Ag &bgr;‘alumina ceramics is characteristic of conductivity fluctuations due to diffusion noise of the mobile ions as previously observed in Na, Ag, and Pb &bgr;‘alumina single‐ion conductors and for mixed‐ion Na/Ca &bgr;‘alumina. The measured diffusion noise levels are greater for current injection of Ag ions from AgNO3solution electrodes. Room‐temperature conductivities calculated from thermal noise measurements are the same for both Na and Ag electrodes and show a strong mixed alkali effect. Correlation effects between the mobile ions are the same for both Na and Ag ion injection and are strongest near the 50/50 concentration ratio.

ISSN:0021-8979    

DOI:10.1063/1.346171

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Hole trapping phenomena in SiO2were examined using an optically assisted hot carrier injection technique onp‐channel insulated gate field effect transistors. It was found that only a single, field‐dependent, capture‐cross‐section hole trap is present. The capture cross section of these hole traps at a field of 4 mV/cm across the gate insulator, corresponding to a gate voltage just above the threshold voltage, was found to be 8.5×10−14cm2. Injected holes were found to trap with an initial efficiency of approximately 60% at this gate field. Depopulation of trapped holes at room temperature was also examined, and found to be significant. The neutral hole trap density in unirradiated device gate insulators after post‐metal annealing was found to be approximately 7.0×1012cm−2. Based on a study of the threshold voltage shift as a function of gate insulator thickness, coupled with the model recently proposed by Walters and Reisman for determining charge centroid, it appears that for oxides with thicknesses greater than 10 nm, the hole traps lie in a band of finite thickness with a charge centroid 5 nm from the substrate‐SiO2interface. In addition, there exists a layer approximately 3.7 nm thick at each interface that appears void of trapped charge. Therefore, oxides less than 7.4 nm thick should not trap charge, which was found to be the case experimentally. This implies that as devices are scaled down, hole trapping will disappear, which is of particular significance in oxides subjected to ionizing irradiation, either during processing or during use.

ISSN:0021-8979    

DOI:10.1063/1.346172

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We calculate the current versus emitter to collector voltage, current versus emitter Fermi energy, and current versus potential energy in the quantum well for double‐barrier resonant tunneling devices having a one‐, two‐, or three‐dimensional electron emitter. We consider both transistor and diode operation of the devices. For each device, the current is obtained using a method which describes the effects of finite temperature, finite voltage, and free‐electron motion perpendicular to the tunneling direction as independent convolutions.

ISSN:0021-8979    

DOI:10.1063/1.346173

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Metal‐oxide‐semiconductor (MOS) capacitors were fabricated on germanium/boron (Ge/B) doped silicon substrates. Typical fixed charge and interface state densities were found to be 5×1010cm−2and 5×1010eV−1cm−2, respectively. Germanium counterdoping in the boron‐doped silicon does not appear to degrade the interfacial properties of MOS structures. Avalanche electron injection produces a slight increase in interface state density, a reduction in inversion capacitance due to deactivation of boron, and a shift in flatband voltage. However, turnaround in flatband voltage shift is not observed due either to enhanced electron trapping or a reduction in donorlike interface state generation. Three different methods used to determine the electron barrier energy height at the silicon dioxide‐Ge/B silicon interface yielded a value of 2.2 eV. This smaller barrier height is attributed to the smaller electron affinity of Ge/B‐doped silicon.

ISSN:0021-8979    

DOI:10.1063/1.346174

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The formation of NbSi2from Nb/Si(100) is studied using rf sputtering and rapid thermal processing. For a long sputter‐etching time (10 min) of the Si substrate, NbSi2is first formed at 720 °C. The lowest resistivity attained is 38 &mgr;&OHgr; cm, one of the best for refractory metal silicides. The variation of the sheet resistance versus annealing temperature is correlated to grain growth. The grain size is deduced from the x‐ray coherence length of the NbSi2(111) peak which sharpens and increases in intensity forT≳720 °C. For shorter sputter etching time (5 min), NbSi2only forms above 895 °C. This is attributed to the native oxide at the Si interface. An estimated ternary phase diagram of Nb‐Si‐O shows that Nb and SiO2coexist at this temperature. Unlike other refractory metal silicides, oxygen in the Nb film is expelled as the silicide is formed.

ISSN:0021-8979    

DOI:10.1063/1.346175

出版商:AIP    

年代:1990

数据来源: AIP