摘要:

Schottky barrier diodes are fabricated on silicon surfaces whose impurity concentrations are controlled by ion implantation techniques. The barriers are produced by PtSi or Al‐Si. The forward characteristics of the diodes show that the forward voltages of Schottky barrier diodes made by PtSi are lower than those made by Al‐Si for implanted doses of 2×1013cm−2and higher. Spreading resistance measurements show that the implanted phosphorus atoms are piled up near the PtSi‐Si interface during PtSi formation. This phenomenon causes reduction of the effective barrier height.

ISSN:0021-8979    

DOI:10.1063/1.331155

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Energy barrier heights at interfaces of metal‐aluminum nitride (AlN)‐silicon(Si) structures with Au and Al as metal electrodes have been measured by internal photoemission. Measured results in low‐photon energy region were interpreted in terms of a hole internal photoemission mechanism. Energy barrier heights for holes from the Au or Al Fermi level and from the top of Si valence band, to the top of AlN valence band, were found to be 2.0±0.2, 3.6±0.2, and 1.9±0.2 eV, respectively. These results were in good agreement with the values measured by the Metal‐Insulator‐Semiconductor capacitance‐voltage techniques. On the other hand, measured results in the high‐energy region were interpreted in terms of both electron and hole emission mechanisms. The band gap energy values of AlN obtained by internal photoemission measurements were nearly equal to the value by optical absorption measurements, except for the value obtained from energy barriers at the Al‐AlN interface. It was also found that the enhancement of photocurrent with time is caused by space charges produced by both electron and hole trappings.

ISSN:0021-8979    

DOI:10.1063/1.331105

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have found that the rate of deposition of Pb when fabricating thin film Al‐oxide‐Pb tunnel junctions has a small but reproducible effect on tunneling characteristics. Zero bias junction conductance is typically increased by a factor of 2 or more when the top electrode deposition rate is raised from 10 to 100 A˚/s. This change is associated principally with a reduction of the effective barrier height at the Pb interface.

ISSN:0021-8979    

DOI:10.1063/1.331156

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The dependence of resistivity, carrier concentration, and grain size upon the impurity concentration and heat‐treatment temperature for heavily As‐ and P‐doped chemical‐vapor‐deposited polycrystalline Si is experimentally investigated, and compared with the resistivity and carrier concentration in single‐crystal Si. It is found that the resistivity and carrier concentration in polycrystalline Si are mainly determined by those in crystallite and the grain size which is dependent upon the heat‐treatment temperature. Evaluating the segregation of As atoms at grain boundaries from the experimental results of As diffusion into single‐crystal Si from polycrystalline Si, it is found that, even when impurity atoms scarcely segregate at grain boundaries, the carrier concentration in polycrystalline Si is lower than that in single‐crystal Si. To explain the phenomenon, it is assumed that impurity atoms are electrically inactive in the disordered region near the grain boundaries. Combining the above assumption and the experimental results, the width of the disordered region and carrier trapping density at grain boundaries are estimated to be 110 A˚ and 4×1012cm−2, respectively, for the samples heat treated at 1200 °C. It is suggested that As‐doped polycrystalline Si has a higher grain boundary barrier resistance than P‐doped polycrystalline Si.

ISSN:0021-8979    

DOI:10.1063/1.331157

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have measured the minority carrier lifetime &tgr;minin liquid phase epitaxial GaP material grown for high‐temperature device applications, as a function of doping concentration, temperature, and epitaxial layer thickness. Inp‐type GaP doped with Mg, &tgr;minremains constant with increasing carrier concentration untilp≊1018cm−3, where it decreases rapidly. For nominally undopedn‐type material we find that &tgr;minincreases by nearly one order of magnitude over the temperature rangeT= 22–600 °C. The apparent lifetimes in these thin‐layer materials increase with layer thickness indicating that surface and interface recombination are important.

ISSN:0021-8979    

DOI:10.1063/1.331106

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The microwave response of the dc quasiparticle tunneling current in Josephson tunnel junctions, where the Josephson current is suppressed by an external magnetic field, has been studied quantitatively in order to clarify its characteristics as a probe for the measurement of the junction capacitance. Extensive experiments for both small and long junctions are carried out for distinguishing between microwave behaviors of lumped and distributed constant junctions. It is shown that the observed voltage dependence of the dc quasiparticle tunneling current modified by an applied rf field is in good agreement with a theoretical result which takes into account the influence of the microwave circuit connected to the junction. The comparison between theory and experiment gives the magnitude of the internal rf field in the junction. Together with the applied rf field, this internal rf field leads to the junction rf impedance which is dominated by the junction capacitance in our experimental condition. In the case of lumped junctions, this experimental rf impedance is in reasonable agreement with the theoretical one with the junction capacitance estimated from the Fiske step of the distributed junction fabricated on the same substrate; the obtained ratio of the experimental impedance to the theoretical one is approximately 0.6–1.7. In the case of distributed junctions, however, experimental values of their characteristic impedances are approximately 0.2–0.3 of theoretical values calculated by assuming the one‐dimensional junction model and taking account of the standing‐wave effect in the junction.

ISSN:0021-8979    

DOI:10.1063/1.331107

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have found that the metastableA‐15 Nb3As phase is present together with the more stable Ti3P‐type Nb3As in sintered samples. The superconducting transition temperature for theA‐15 phase is 6.5 K and the upper critical field at 0 K is 1.82 T.

ISSN:0021-8979    

DOI:10.1063/1.331108

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Using the technique of ’’surface permeabilities,’’ an expression is derived for the dispersion of magnetostatic waves propagating in two close proximity ferrimagnetic films. Two modes of propagation for volume waves are identified respectively as the symmetric and antisymmetric modes from the symmetry of the rf magnetization. Useful group delay behavior is shown to result from films of equal thickness. Some measurements are reported using two yttrium iron garnet films sandwiching simple single finger transducers. Difficulties in exciting the symmetric forward volume mode are explained in terms of the coupling coefficients for these double film structures.

ISSN:0021-8979    

DOI:10.1063/1.331109

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Magnetization reversal in GdCo5single crystals was studied by magnetization measurements at various temperatures. The effective nucleation fieldH*nincreases with decreasing temperature. A linear relationship is observed betweenH*nand the amount of magnetization reversal in a jump at all temperatures studied. The lifetime of the moving walls in the magnetization jump decreases as the temperature falls. The average velocity of the domain walls is estimated to be approximately 18 m/s at 4.2 K. The temperature dependence ofH*nhas been interpreted in terms of a thermally activated process.

ISSN:0021-8979    

DOI:10.1063/1.331110

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A high coercivity and a high hysteresis loop squareness pure Co and Co‐Ni (up to 50 at %) alloy films have been prepared by a new process. The new process involves the films, including N, being sputter deposited in an atmosphere of Ar‐N2mixture and annealed at temperature above 553 K. Most of the included N diffuses out from the film surface after annealing, and the films have a strong preferred orientation with thecaxis parallel to the film plane. In Co70Ni30alloy films, a high coercivityHcof 1 kOe (80 kA/m) and a high hysteresis loop squarenessS* of 0.95 are achieved. The values ofHcgradually decrease as the Ni/Co concentration ratio of the films departs from 30/70. There is a strong correlation betweenHcand the preferred orientation of crystallites;Hcincreases as thecaxis orientation parallel to the film plane grows.

ISSN:0021-8979    

DOI:10.1063/1.331111

出版商:AIP    

年代:1982

数据来源: AIP