摘要:

X‐ray photoemission spectroscopy data are used to correlate the interface Fermi‐level pinning energyEiFand the corresponding interface chemistry forn‐type andp‐type InP (100) samples simultaneously subjected to a series of surface treatments. Interfaces of Schottky‐barrier contacts formed during a sequence of Au and of Al depositions made both onto chemically etched and thermally cleaned InP surfaces were investigated. Changes inEiFof up to ∼0.6 eV in the upper half of the InP band gap occurred in response to changes in interface chemistry. The observed behavior ofEiFis interpreted in terms of a single defect model with multiple charge states.

ISSN:0003-6951    

DOI:10.1063/1.93968

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

High resolution masked ion beam lithography (MIBL) is demonstrated at large mask‐to‐sample gaps using two new types of membrane stencil masks. Single layer Si‐rich silicon nitride (SiN) membranes and Si3N4‐SiO2‐Si3N4(N‐O‐N) sandwich structure membranes are deposited by processes which allow the stress in the films to be adjusted. Transmission holes are reactive‐ion etched entirely through the membranes. This type of stencil mask virtually eliminates mask‐induced scattering. Lines and spaces of 160 nm have been exposed in 0.5‐&mgr;m polymethylmethacrylate (PMMA) at gaps as large as 275 &mgr;m, using 100‐keV protons. Some of the stencil mask limitations are overcome by multiple exposures. The results suggest that MIBL can be an extremely high resolution proximity printing technique.

ISSN:0003-6951    

DOI:10.1063/1.93969

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A reproducible process is described for growing a thick single‐crystal layer of cubic SiC on a single‐crystal Si wafer by chemical vapor deposition. A buffer layer, growninsitu, is used between the cubic SiC and the Si substrate to minimize the effect of lattice mismatch. Layers of up to 34 &mgr;m thick and several cm2in area have been grown. Wafers are obtained by chemically removing the Si substrates from the grown layers. Excellent electron channeling patterns produced by these wafers indicate very good crystal quality. Preliminary electrical measurements have yielded electron mobilities up to 380 cm2/Vs.

ISSN:0003-6951    

DOI:10.1063/1.93970

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

(100) Ge‐GaAs superlattices grown by molecular beam epitaxy have been analyzed using He+ion channeling spectrometry. Over the individual layer thickness of 25–100 A˚ for Ge and GaAs in the superlattices, very low dechanneling yields are observed along the ⟨110⟩ axis. Dechanneling yields along the [100] growth direction, however, are low only for the thicker layer structure, and become increasingly larger than the ⟨110⟩ ones for the thinner layer structures. These results are opposite to the ones for the InAs‐GaSb superlattices where dechanneling yields along the ⟨110⟩ axis are much higher than the [100] ones for all the superlattices studied. The channeling results are compared with those using other techniques and their implications on the Ge‐GaAs interfaces discussed.

ISSN:0003-6951    

DOI:10.1063/1.93971

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We have investigated the characteristics of flame annealing of ion implantation damage in (100) and (111) silicon substrates using transmission electron microscopy and Van der Pauw measurements. The temperature of the hydrogen flame ranged from 1050 to 1200 °C and the interaction time from 5 to 10 s. Transmission electron microscopy studies showed that a ‘‘defect‐free’’ annealing could be achieved with concomitant full electrical activation of dopants. The Hall mobility of flame annealed specimens was found to be comparable to pulsed laser annealed specimens.

ISSN:0003-6951    

DOI:10.1063/1.93972

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Powder metallurgy processed submicron multifilamentary Nb3Sn superconducting wires were fabricated starting with 250–500‐&mgr;m‐diam powders. A multiple strand bundling procedure was used to simulate large scale production with actual areal reductions greater than 106to achieve submicron fibers. Both external tin and tin core processing were successful. Typical Cu‐36 wt.% Nb‐Sn materials gave overall critical current densities of 8×104A/cm2at 12 T, 3×104A/cm2at 14 T, and 6×103A/cm2at 16 T. These results demonstrate that particle size and billet size can be scaled from earlier laboratory scale to large scale fabrication to produce high performance materials.

ISSN:0003-6951    

DOI:10.1063/1.93973

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Preparation of high quality all‐refractory Josephson tunnel junctions based on Nb/Al‐oxide‐Nb and Nb/Al‐oxide‐Al/Nb structures is reported. Critical currents up to 1300 A/cm2andVmvalues up to 35 mV were obtained. The specific capacitance of these junctions is 0.06±0.02 pF/&mgr;m2. Junctions were fabricated using standard photolithography and a new plasma etching process coupled with anodization of Nb.

ISSN:0003-6951    

DOI:10.1063/1.93974

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Voltage‐current characteristics of a superconducting closed loop which consists of a parallel combination of two linear series arrays ofN‐Josephson junctions are theoretically and experimentally investigated forN=3. The results show that the rf‐induced constant voltage steps inv‐icharacteristics in the presence of the rf radiation of frequencyFappear at voltages corresponding tonNF&Fgr;0with an integern. We find that the junctions show a coherent behavior even though the closed loop does not consist of identical junctions. The voltage standard application of this circuit seems feasible.

ISSN:0003-6951    

DOI:10.1063/1.93975

出版商:AIP    

年代:1983

数据来源: AIP