摘要:

A technique is presented for determining the enhancement in solid‐state diffusion caused by low‐energy ion bombardment. In this technique, superlattice films are grown under varying conditions of ion bombardment and the amplitude of the resulting composition modulation wave is determined by analyzing x‐ray diffraction satellite peaks surrounding the central Bragg peaks. The amplitude is in turn related to the enhanced diffusion coefficientD* (x) which may be expressed asD*0 exp(−x/&dgr;) where &dgr; is a characteristic diffusion length of the ion‐bombardment‐produced defects. This approach was confirmed experimentally using InSb/GaSb superlattice structures grown by multitarget sputtering, each sample having equilayer thicknesses between 12 and 30 A˚.D* was found to increase as the sputtering pressure was decreased. Measured values ofD* averaged over the enhanced diffusion region were on the order of 10−17cm2/sec compared to a thermal interdiffusion coefficient of approximately 10−22cm2/sec at the film growth temperature of 250 °C.

ISSN:0003-6951    

DOI:10.1063/1.90330

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Ohmic contacts of AuGe have been produced on GaAs epilayers by laser alloying. The contacts possess morphological and electrical properties which are superior to those formed by conventional alloying.

ISSN:0003-6951    

DOI:10.1063/1.90331

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The formation of oxidation‐induced stacking faults in the surface regions of silicon wafers can be eliminated by a short‐period anneal in a dry nitrogen atmosphere containing small concentrations of HCl and oxygen in the same furnace where subsequent oxidation will be carried out. This preoxidation anneal results in the prevention of fault nucleation without causing any problem like a nitridation reaction, an etch‐pit formation, and a blotchy appearance on the silicon surface.

ISSN:0003-6951    

DOI:10.1063/1.90332

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The effective electron mobility ofN‐channel MOSFET’s with different gate oxide thickness has been measured at 4.2 K as a function of electron density. An increase in the peak effective mobility is observed as the oxide thickness is increased. It is found that the peak mobility is determined by the scattering mechanism whose scattering probability is independent of electron density. To describe these experimental results, the scattering by a short‐ranged potential has been assumed and discussed.

ISSN:0003-6951    

DOI:10.1063/1.90333

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Breakdown voltages have been calculated for abruptp‐njunctions in the nine III‐V semiconductors of AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb. Parameters needed in the breakdown voltage calculations such as the mean free path for scattering and the average phonon loss have been evaluated using a Monte Carlo transport calculation at electric field values characteristic of breakdown.

ISSN:0003-6951    

DOI:10.1063/1.90334

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The conductance of amorphous Si films produced by glow discharge of SiH4is found to be very sensitive to various adsorbates such as water, ammonia, and dimethyl ether. Films exposed to air and light must first be heated to 150 °C in vacuum to remove adsorbed moisture and the reversible photoelectronic effect discovered by Staebler and Wronski. When exposed to adsorbates, the conductance of undoped films (about 0.36 &mgr;m thick) decreases by several orders of magnitude; the conductance of lightly phosphorus‐doped films first increases rapidly and then slowly decreases to a saturation value which lies above the conductance of the annealed films. Heating in vacuum at 150 °C restores the original values. The results indicate that the conductance changes produced by light and by adsorbates are two separate processes, the latter being a surface effect.

ISSN:0003-6951    

DOI:10.1063/1.90335

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Coherent tunable microwave radiation (2–18 GHz) has been observed from two microbridge Josephson junctions coupled by a shunt resistor. The coherent power (∼4×10−12W) is nearly four times the power emitted by a single junction. The linewidth of the radiation in the coherent state is one‐half that from the individual microbridges.

ISSN:0003-6951    

DOI:10.1063/1.90336

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Analyses of high‐TcNb3Ge films show that they all have a peak in oxygen concentration near the substrate‐film interface and that their lattice parameters in that region are abnormally large. It is proposed that high‐TcNb3Ge is a metastable phase which is formed via a homoepitaxial process from a large lattice parameterA15 Nb‐Ge phase. This phase near the interface is believed stable due to an expanded lattice resulting from the presence of impurities.

ISSN:0003-6951    

DOI:10.1063/1.90337

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Mo¨ssbauer effect measurements of57Fe in a Cr‐Co‐Fe alloy indicate the existence of two ferromagnetic phases at room temperature. The hyperfine field of the two phases differ by ∼11%. This result implies that domain‐wall–particle interaction is responsible for the coercive force, which is a different mechanism than in some Alnico alloys.

ISSN:0003-6951    

DOI:10.1063/1.90338

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The phase of the dynamic polarization echo with respect to the second driving pulse has been measured for several powdered materials. The mechanism for echo formation, in all the materials that were examined, was found to be an anharmonic oscillator interaction with a nonlinear amplitude‐dependent frequency.

ISSN:0003-6951    

DOI:10.1063/1.90339

出版商:AIP    

年代:1978

数据来源: AIP