摘要:

Interactions of PtTi, NiTi, AlPt, and AlNi compounds with Si substrates were analyzed by a combination of backscattering spectrometry and transmission electron microscopy. The reaction occurs via the migration of Si into the alloy matrix at temperatures between 500 and 600 °C. Uniform mixing rather than phase separation is observed in all the systems investigated. Ternary compounds (PtTiSi, NiTiSi2, AlPtSi, and Al2Ni2Si) are formed in the reacted layer and exhibit a high stability to heat treatment at elevated temperatures. These reactions were rationalized in terms of the free energy change of the reacted systems and the mobilities of various atoms.

ISSN:0021-8979    

DOI:10.1063/1.337388

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

An electrochemical cell Pt/AgI/Ag2 X/Pt (X=S,Se) has been used as a highly controllable source of chalcogen dimers forn‐type doping of Ga1−xAlxAs grown by molecular‐beam epitaxy (MBE). The incorporation behavior has been investigated as a function of alloy composition, growth temperature, and arsenic overpressure. At low temperatures, <600 °C, sulfur and selenium are incorporated into Ga1−xAlxAs in a facile manner. At higher temperatures, where loss of chalcogen dopant from GaAs has previously been observed, sulfur shows an enhanced stability in the aluminum‐containing alloys. Excess As4is shown to hinder the loss further. The behavior is modelled in terms of the relative stabilities of the volatile and involatile gallium and aluminum chalcogenides under MBE growth conditions.

ISSN:0021-8979    

DOI:10.1063/1.337389

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The influence of planar channeling on the atomic profiles of low‐dose Si+implants into GaAs is demonstrated as a function of wafer rotation angle, ion beam incidence angle, wafer crystallinity, and thickness of dielectric coating on the surface of the wafer during implantation. Use of a controlled wafer rotation angle or implantation through a dielectric layer results in reproducible profiles free of planar channeling effects. However, even these implants still show a significant profile ‘‘tail’’ that is absent for implants into preamorphized material, thus suggesting the existence of significant residual channeling in GaAs.

ISSN:0021-8979    

DOI:10.1063/1.337390

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Thin films of an iron–tellurium alloy were prepared by rf sputtering and characterized by means of x‐ray diffraction and Mo¨ssbauer spectroscopy. In an immiscible range in equilibrium composition, tellurium atoms were incorporated into iron, distorting the lattice to some extent. Beyond 14 at. % of Te, an amorphous structure appeared. Judging from the metastable superstructures formed at higher substrate temperatures and the covalent nature in the bonding, the kinetic hindrance against the redistribution of the elements due to the local atomic forces during rapid quenching plays a critical role in the formation of amorphous structure in this alloy. In addition, beyond some intermetallic range around 60 at. % Te, an amorphous phase also exists in the tellurium‐rich region. The thermal stability was examined by a differential scanning calorimetry; the electrical resistivity is also discussed.

ISSN:0021-8979    

DOI:10.1063/1.337391

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Detailed analysis of Raman spectra recorded from (100)‐oriented GaAs layers grown by molecular‐beam epitaxy on the lattice‐matched insulator (Ca,Sr)F2gives evidence of internal misorientation effects (twins). This analysis accounts for the various phenomena (doping, disorder, electron‐phonon coupling) likely to modify the scattering efficiency. Calculations are performed in order to obtain quantitative evaluations of the misoriented volume amount.

ISSN:0021-8979    

DOI:10.1063/1.337392

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Donor‐related deep levels in Se‐doped In0.5(Ga1−xAlx)0.5P (x=0.0–1.0) have been studied by DLTS,C–Vmeasurement, and photocapacitance techniques. Two donor‐related deep levels were found. The concentrations linearly increased with the donor concentration, and strongly depended on the alloy composition. These levels were found to be dominant donors in the composition range fromx=0.3 tox=1.0. They had 0.20 and 0.29 eV activation energies for electron thermal emission, 0.08 and 0.11 eV energies for electron thermal capture, and they had 0.7 and 1.1 eV energies for electron optical emission, respectively. Internally consistent configuration coordinate diagrams were proposed for these levels, suggesting that both levels are similar toDXcenters commonly found inn‐AlGaAs.

ISSN:0021-8979    

DOI:10.1063/1.337393

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Using a new model relating dislocation charge to Fermi level, we have simulated the differential capacitance resulting from the inclined dislocations accompanying the misfit dislocations in epitaxial InGaAs/InP samples. The result is a quadratic dependence of charge upon mismatch which is in quantitative agreement with experiments of Macranderetal. for a misfit dislocation segment length equal to about nine times the dislocation spacing.

ISSN:0021-8979    

DOI:10.1063/1.337394

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The field‐dependent capture‐emission process has been studied for double Poole–Frenkel well traps compared with that of single Poole–Frenkel well trap. The emission rate increases with increasing field strength for a single trap. However, for a double trap, it increases to a maximum then decreases with further increasing field due to the barrier lowering and interstate interactions between these two wells. Experimental capacitance deep‐level transient spectroscopic data of GaAs samples grown by molecular‐beam epitaxy show that when there is a delay in the capacitance transient then there always appear two levels, namely, 0.4 and 0.5 eV. In addition, for both levels, the emission rate increases first to a maximum and then decreases with increasing electric field.

ISSN:0021-8979    

DOI:10.1063/1.337395

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Intrinsic or lightly boron‐doped amorphous silicon films were produced by chemical vapor deposition (CVD) from disilane at temperatures from 380 to 460 °C and at growth rates from 0.1 to 40 A˚/s. The density of states (DOS) near the middle of the mobility gap was determined by space‐charge‐limited conduction onn‐i‐nstructures and by steady‐state capacitance‐temperature spectroscopy onp‐i‐nstructures. Very close agreement was found between the two techniques for intrinsic layers deposited under similar conditions. The DOS distribution is rather flat from 0.60 to 0.75 eV from the conduction‐band edge and has a range of 1–6×1017cm−3 eV−1for intrinsic films, with the minimum occurring for depositions at 440 °C independent of growth rate or contaminants in the disilane. Diborane levels from 9 to 18 ppm in the gas phase reduces the DOS at 440 °C to 3–6×1016cm−3 eV−1. The exponential absorption below the band edge in the range 1.4–1.6 eV was determined from primary photocurrent spectra ofp‐i‐nstructures. The Urbach edge parameterE0ranged from 0.048 to 0.056 eV with the minimum also occurring for depositions at 440 °C, independent of growth rate and boron content. Comparison to glow‐dischargea‐Si:H films indicates that CVDa‐Si:H films have a similar amount of structural disorder, determined fromE0, but an inherently larger DOS deep in the gap. A model is proposed in which boron reduces the high midgap dangling bond density caused by insufficient weakly bonded hydrogen in the film as a consequence of the high deposition temperatures. The model is consistent with other measurements, such as hole collection width.

ISSN:0021-8979    

DOI:10.1063/1.337396

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The temperature dependence of the free‐carrier concentration in germanium doped with the double acceptor Be has been investigated using the photo Hall‐effect technique and found to be strongly temperature dependent when the residual shallow impurities are closely compensated. Close compensation (NA&bartil;ND) of shallow levels was achieved by controlling the concentration of a beryllium–hydrogen acceptor complexA(Be,H) which is present in crystals grown under a H2atmosphere. This complex can be removed with high‐temperature annealing. An increase of up to two orders of magnitude in free‐carrier lifetime as a function of temperature is found to occur between 5 and 11 K in closely compensated material due to the population inversion of ionized centers created by optical pumping.

ISSN:0021-8979    

DOI:10.1063/1.337397

出版商:AIP    

年代:1986

数据来源: AIP