摘要:

After depositing a 1/6 monolayer of AlAs on a very flat GaAs (001) surface by metalorganic vapor‐phase epitaxy, we have studied AlAs two‐dimensional (2D) nuclei by high‐vacuum scanning tunneling microscopy. AlAs 2D nuclei elongate in the [110] direction, like GaAs. The density of AlAs 2D nuclei in the saturation region was 5×1010cm−2at 580 °C. The saturated AlAs 2D nucleus density decreased as the temperature increased. From the saturated AlAs 2D nucleus densities the surface diffusion coefficient of AlAs on GaAs was calculated to be 1.5×10−7cm2/s at 530 °C. This is one order of magnitude smaller than that of GaAs on GaAs. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114803

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Optical and electrical properties of Hg acceptor in GaAs were systematically investigated as a function of Hg concentration. Samples were prepared by high‐energy ion implantation of Hg+into GaAs grown by liquid encapsulated Czochralski method. Annealing was made by rapid thermal annealing using infrared flash lamp at 950 °C during 3 s. Photoluminescence measurements at 2 K revealed that in addition to the well‐defined conduction band to Hg acceptors transition, the mercury‐related so‐called ‘‘g’’ neutral acceptor bound exciton band is found shifted from the carbon‐related ‘‘g’’ line by 0.8 meV. Moreover, two shallow emissions, are formed for net hole concentration ‖NA−ND‖ greater than 2×1017cm−3and 1×1019cm−3, respectively. It is demonstrated that even a typical moderately deep acceptor Hg in GaAs, having ground‐state ionization energy of 52 meV can make multiple shallow emission levels presumably attributed to acceptor–acceptor pairs. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114804

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The homoepitaxial growth of GaAs(110) thin films by molecular beam epitaxy has been studiedinsituby reflection high‐energy diffraction. RHEED specular beam intensity oscillations were recorded over a wide range of growth conditions in which the substrate temperature, growth rate, V/III flux ratio and the relative amount of As2or As4in the incident arsenic beam were varied. These conditions were plotted to produce a phase map of the growth conditions for which specular intensity oscillations were recordable. RHEED oscillations were obtained over a much wider range of growth conditions when using As2compared to growth using As4. It is shown that this is related to the very different incorporation coefficients of the two arsenic species and reflects the requirement of a high arsenic adatom concentration in order to maintain the 1:1 stoichiometry of the nonpolar (110) surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114805

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a joint theoretical and experimental investigation of GaAs v‐groove quantum wires confined in GaAs/AlAs superlattice barriers. We have computed the electronic states for both the quantum wire and the barriers. The intrinsic bending of the superlattice layers, together with systematic spatial variations of their thickness, create localized states in the barriers that are separated from the wire. This effect has a strong impact on the overall luminescence efficiency of the wires. The results are in excellent agreement with photoluminescence and photoluminescence excitation spectra. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114806

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The local oxide defects observed in thin silicon dioxide films onp‐type Si were studied with the electron beam induced current/tunneling current microscopy technique. Excluding pinholes, all the local defects observed are local oxide/substrate defects, i.e., local oxide defects propagated from defects in the Si substrate into the SiO2. It was observed that local oxide/substrate defects can be further differentiated into two different types by studying the transition from the true oxide electron beam induced current contrast to the tunneling current microscopy contrast. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114807

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have examined the role of carbon co‐implantation in the formation of secondary defects in self‐ion‐irradiated Si(100). Implantation of Si ions (540 keV energy, 1015ions/cm2at 1.3×1011ions/cm2/s,Ti=90 °C) followed by a 900 °C, 15 min anneal leads to the growth of an extended defect band at the end of range. Range matched‐carbon co‐implantation (300 keV energy, 1015ions/cm2plus 500 keV energy 1015ions/cm2of 1.5×1011ions/cm2/s,Ti=90 °C) can be used to modify this defect development dramatically. While direct co‐implantation of carbon and silicon ions to similar concentrations has no apparent effect on the formation of extended defects, such formation is suppressed when the implanted C is incorporated substitutionally into the silicon lattice. These results are discussed in the context of recent reports on C suppression of the transient enhanced diffusion of boron. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114808

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effects of reactive ion etching (RIE) and Fowler–Nordheim (FN) gate current stresses upon both the 1/f&ggr;and random telegraph signal (RTS) noise characteristics of submicrometer gate area metal oxide semiconductor field‐effect transistors has been analyzed. While control devices exhibit the Lorentzian noise spectra and discrete switching behavior attributable to single oxide defects, the first layer metal antenna devices exhibit degraded RTSs and near ideal 1/fnoise characteristics. An evolution of this 1/fbehavior has been reproduced in control devices by subjecting them to a series of UV illuminated FN gate current stresses. Results of this study suggest that multiple oxide traps with a distribution in time constants are generated during RIE and that the amount of oxide degradation generated during plasma etching may be more substantial than that produced during plasma ashing. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114809

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A quantitative determination of the contribution of As self‐interstitials to the As self‐diffusion coefficient in GaAs has been carried out. Values of the As self‐interstitial contributions are deduced from sulfur indiffusion profiles in GaAs, which are simulated based on the kick‐out mechanism. Furthermore, the relative contributions of As self‐interstitials and of As vacancies are discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114810

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Superconducting Hg‐based cuprate thin films have been fabricated on (100) SrTiO3substrate using rf sputtering and post‐Hg‐vapor annealing. These films are dominated byc‐axis‐oriented Hg‐1223 phase as indicated by x‐ray diffraction and SQUID measurements. Using four‐probe technique, theTc,onsetwas found to be 130–132 K andJcwas up to 8.5×104A/cm2at 77 K and zero field. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114811

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have implemented a simple circuit of the rapid single‐flux‐quantum (RSFQ) logic family using a single‐layer YBa2Cu3O7−xthin‐film structure with 14 in‐plane Josephson junctions formed by direct electron beam writing. The circuit includes two dc/SFQ converters, two Josephson transmission lines, a complete RS SFQ flip‐flop, and an SFQ/dc converter (readout SQUID). Low‐frequency testing has shown that the dc‐current‐biased circuit operates correctly and reliably atT∼30 K, a few degrees below the effective critical temperature of the junctions. Prospects for a further increase of the operation temperature and implementation of more complex RSFQ circuits are discussed in brief. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114812

出版商:AIP    

年代:1995

数据来源: AIP