摘要:

Using the Boltzmann transport equation, calculations were obtained predicting the zones of stoichiometric imbalance produced in GaAs after ion implantation at energies of 50, 100, and 300 keV. The recoiling Ga and As atoms were shown to produce a zone of interstitials at depths exceedingRp. Secondary‐ion mass spectrometry profiling indicated that Cr was rapidly redistributed into these regions at temperatures ⩽500 °C. Transmission electron microscopic analyses obtained on horizontally sectioned and vertical cross section samples indicated that the interstitials coalesced into small clustered sites (50–100 A˚) and were responsible for the development of Cr gettering at depths ≳Rp.

ISSN:0003-6951    

DOI:10.1063/1.92602

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

n‐channel deep‐depletion mode metal‐oxide‐semiconductor field‐effect transistors (MOSFET’s) have been fabricated in Si films prepared by zone‐melting recrystallization of chemical‐vapor deposited (CVD) polycrystalline Si deposited on SiO2‐coated Si substrates. The transistors exhibit surface electron mobility in the range of 600–700 cm2/Vs, comparable to values for devices fabricated in single‐crystal Si. Measurements of electron mobility as a function of gate bias voltage indicate that the mobility is nearly constant throughout the depth of the recrystallized Si films. Mobility of 650–700 cm2/Vs at the lower Si‐SiO2interface and subthreshold source‐drain leakage current of a few pA/&mgr;m (channel width) have been measured.

ISSN:0003-6951    

DOI:10.1063/1.92603

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The electron mobility of single modulation‐doped GaAs‐(AlGa)As heterojunctions is strongly dependent on electron density and Al concentration. A low‐temperature persistent photoconductive effect is employed to vary the areal electron densitycontinuouslywithin asinglesample by nearly a factor of 3. Over this density range the mobility increases monotonically by as much as a factor of 4, quasilinear with density. At equivalent carrier concentrations heterojunctions with lower Al concentration show higher mobilities. At low temperatures a peak mobility of 365 000 cm2/Vs is found at an areal density of 7.0×1011cm−2with an interparticle spacing equivalent to a three‐dimensional density of 5.9×1017cm−3.

ISSN:0003-6951    

DOI:10.1063/1.92604

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Auger and electron loss spectroscopies, low energy electron diffraction (LEED) and depth profiling techniques have been applied to the study of the Au/Si (111) interface under UHV conditions. The results, obtained at room temperature, show the formation on top of the substrate of (i) a diffuse and alloyed interface of ∼15‐A˚ thickness, (ii) a pure Au film, and (iii) a Si enriched surface monolayer. The modifications of the interface structure in air have been checked by MeV ion microanalysis and channeling, for various gold coverages ranging between ≃1 monolayer up to ?100 A˚. In all cases, drastic changes occur. Results related to18O tracing experiments confirm the presence, under UHV, of Si atoms on the topmost layer. But the main fact is that a very strong Si diffusion through the gold layer takes place in air at room temperature for all the samples studied, leading to the formation of a surface silicon oxide layer much thicker than observed on samples without gold coverage.

ISSN:0003-6951    

DOI:10.1063/1.92605

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Based on results of two quite different experiments, we report microslip‐induced degraded performance of a braided superconductor. Microslips, or more formally, microscopic slips, are inherent in all sliding events and are quite different from the well‐known stick slips that occur, on a macroscopic scale, for ’’unstable’’ sliding pairs. Microslips occur universally in all material pairs. Their effects are, in general, innocuous except in low‐temperature situations such as those found in superconducting magnet windings. Because materials have extremely low‐heat capacities at 4.2 K, the miniscule amount of energy released by a microslip can precipitate a quench in the superconducting magnets.

ISSN:0003-6951    

DOI:10.1063/1.92606

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Initial results on laser‐induced chemical vapor deposition using the visible radiation of an Ar+laser are presented. Due to the smaller wavelength of Ar+laser radiation in comparison to the infrared radiation of a CO2laser used in earlier experiments, much finer patterns could be produced. The influence of laser irradiance on the deposition rate and widths of patterns was investigated.

ISSN:0003-6951    

DOI:10.1063/1.92607

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An absolute pressure sensor is reported that uses electrochemical pumping of oxygen. Sensor operation uses the pressure dependence of O2diffusion in a host gas. The device is unusual because no reference pressure or vacuum is required for absolute measurements. The main features of device operation are in agreement with calculation.

ISSN:0003-6951    

DOI:10.1063/1.92608

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We demonstrate here that bilayer films consisting of Si and transition metals with a layer thickness of 15–40 nm are promising materials for archival optical storage. They show a large optical reflectivity change before and after silicide formation, have a long lifetime at room temperature, and are nontoxic.

ISSN:0003-6951    

DOI:10.1063/1.92609

出版商:AIP    

年代:1981

数据来源: AIP