摘要:

The first solid‐state heterojunction device involving two conducting organic polymers has been fabricated from polyacetylene, (CH)xandp‐doped poly(N‐methylpyrrole), (PNP). Its electronic properties can be modified by chemically partly reducing or partly oxidizing the PNP. The junction has been characterized byJ‐Vstudies and by preliminary photovoltaic measurements.

ISSN:0021-8979    

DOI:10.1063/1.336095

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new procedure to profile deep‐level densities within the space‐charge region of Schottky barriers is presented. The method takes advantage of the spatial dependence of the time constant for the free‐electron capture by deep‐donor traps. The amplitude of the slow component of the capture capacitance transient following a negative reverse voltage pulse is simply related to the trap density at the point where the Fermi level crosses the trap level itself. The density profile of a given trap can be achieved by measuring the slow‐component transient signal as a function of the reverse voltage at a suitably chosen constant temperature. The estimated spatial resolution of the method was near 50 A˚ in a practical case. Experimental density profiles for EL14, EL8, EL3, and theEC−ET=0.37 eV level in Cr/GaAs and Al/GaAs Schottky barriers are presented and discussed. The procedure is expected to be also applicable to the case of trap densities comparable with the shallow‐donor density without introducing large errors.

ISSN:0021-8979    

DOI:10.1063/1.336096

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The admittance of Schottky diodes formed on dc triode sputtered amorphous hydrogenated silicon has been measured as a function of frequency at zero dc bias. The electrical behavior of the device is modeled with an equivalent circuit taking into account the thermal response time of gap states and the transport of carriers in the conduction band. The theoretical frequency dependence of the admittance of the Schottky diode is derived in two limiting cases: whether the occupancy of the gap states is controlled mainly by their interaction kinetics with the extended states or by the transport of electrons in the conduction band. We reach the conclusion that, in our samples, the response to an ac modulation is limited by the interaction kinetics of the localized states with the extended states of the conduction band. We apply this analysis to samples exposed to different sputtering conditions. The results show that, with these samples, not only the density of deep gap states at the Fermi level but also their efficiency for the capture of electrons decreases with hydrogen incorporation. These variations correlate well with the evolution of the electron mobility‐lifetime product obtained from independent photoconductivity measurements.

ISSN:0021-8979    

DOI:10.1063/1.336097

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Theenergydistributionof hot electrons in high‐field stressed amorphous silicon dioxide (SiO2) films have been measured using a vacuum emission technique. Electrons having average energies ≳2 eV and an energy relaxation length of &lgr;≊32 A˚ are observed at all fields studied (≳ 2 MV/cm). However, contrary to previous theoretical expectations, the majority of carriers in the distribution remains stable at all fields. The results are in agreement with other recent experiments (electroluminescence and carrier separation) which only measure theaverageenergyof hot electrons in SiO2and with recent Monte Carlo transport calculations which include scattering by both optical and acoustic phonon modes. Results for varying SiO2thickness, metal gate thickness, oxide composition, and metal gate composition will be discussed.

ISSN:0021-8979    

DOI:10.1063/1.336098

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The Engel–Brewer theory for transition metals has been extended to transition metal silicides. It is shown that the promoted electronic state correlates well with the properties of the silicides. From these correlations we are able to predict the effect of deviations from stoichiometry on disilicide resistivity and the existence of other silicide crystal structures.

ISSN:0021-8979    

DOI:10.1063/1.336099

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Most tunnel barriers contain localized electronic statesnl(&Dgr;x, &egr;) in large amounts decreasing with distance &Dgr;xfrom the metal. The localized states hybridize with conduction electrons forming interface states with a decay width &Dgr;l∝exp(−2&Dgr;x&kgr;) and a correlation energy &Dgr;U* ∝ 1/&egr;r&Dgr;x. For &Dgr;U*>&Dgr;lthese states are localized, which yields a strong coupling to surface plasmons, phonons, and spins. These states cause diffuse surface scattering and enhance exponentially [∝ &Dgr;−1l ∝exp(+2&Dgr;x&kgr;)] the tunnel matrix element by resonant tunneling jRas compared to tunnelingj&fgr;¯through the whole potential barrier &fgr;¯. Consequently at voltages ‖eU‖ <&fgr;¯,jR(U,T) is identified by its strongerUandTdependencies and can even dominate overj&fgr;¯. The enhanced interaction of the localized electrons with surface plasmons, phonons, and spins yield strongU,T, and time dependencies in the tunnel current which produce giant zero‐bias anomaly and spin‐flip zero‐bias anomaly; capacitance changes; inelastic processes, noise, and barrier reduction with increasing temperature; and pair weakening, leakage current, and reduction of the Josephson current.

ISSN:0021-8979    

DOI:10.1063/1.336100

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Trap generation during low‐fluence avalanche‐electron injection (AEI) in metal‐oxide‐silicon capacitors (MOSC’s) with different fabrication processing cycles was investigated. Injection gate voltages from 45 to 65 V for an oxide of 1000 A˚ thickness were used to simulate hot‐electron effects in oxidized silicon under transistor operation conditions. Experimental results indicate that more negatively charged traps are generated in wet oxide than dry oxide. Different trap‐generation phenomena in poly‐Si‐ and aluminum‐gate MOSC’s were observed. The midgap voltage shift of aluminum‐gate MOSC during AEI is not appreciably dependent on the magnitude of the peak AEI voltage, while that of poly‐Si‐gate MOSC has a strong dependence. The generation rate of interface states in aluminum‐gate MOSC is much smaller than that of poly‐Si‐gate MOSC. The results are interpretable by the hydrogen model.

ISSN:0021-8979    

DOI:10.1063/1.336101

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We have studied the Er and ErSi2contacts onp‐Si. A correlation is found between the barrier height and the presence of an interfacial oxide layer. Samples with a thin interfacial oxide (∼ 3 A˚) exhibit a barrier height of 0.68 eV. In contrast, samples without any detectable interfacial oxide show a higher barrier height of ∼0.8 eV. The barrier heights were determined by current‐voltage measurements and the thicknesses of the interfacial oxide were measured by the16O(d,&agr;)14N nuclear reaction technique.

ISSN:0021-8979    

DOI:10.1063/1.336102

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Vanadium dioxide undergoes a transition at about 68 °C where the physical properties of the oxide, in particular the index of refraction and possibly the density, abruptly change values. In this work the indices of refraction of thermally grown films of vanadium dioxide on a vanadium substrate have been determined at room temperature and at 84 °C using the technique of ellipsometry. The index of refraction found for these films in this work is 2.82–0.317iat room temperature and 2.24–0.456iat 84 °C. In addition, our results indicate that there is a small increase in the thickness of each film upon heating through the transition.

ISSN:0021-8979    

DOI:10.1063/1.336103

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In this paper, we report a parametric study of pulsed‐laser cutting of thin metal plates. The physical processes of laser‐material interaction involving material removal are explored through a systematic study of pulsed‐laser cutting of various metal plates of different physical properties. The roles of assist gas in the cutting process was also investigated.

ISSN:0021-8979    

DOI:10.1063/1.336104

出版商:AIP    

年代:1985

数据来源: AIP