摘要:

The measurement of thermal stress of SrF2films on InP as a function of temperature is presented. Theinsituandexsiturapid isothermal annealed films have different values of thermal stress at room temperature and show entirely different behavior of thermal stress during heating and cooling cycles. X‐ray photoelectron spectroscopy measurements were used to characterize the surface of the SrF2films as well as the SrF2/InP interface for both theexsituandinsituannealed films. It is shown that the difference in the microstructure ofinsituandexsiturapid isothermal annealed SrF2films on InP is indeed reflected in the significant difference in the thermal stress.

ISSN:0003-6951    

DOI:10.1063/1.103496

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Correlations between the surface chemistry of etched, (100) orientedn‐GaAs electrodes and their subsequent photoelectrochemical behavior have been probed by high‐resolution x‐ray photoelectron spectroscopy. GaAs photoanodes were chemically treated to prepare either an oxide‐free near stoichiometric surface, a surface enriched in zero‐valent arsenic (As0), or a substrate‐oxide terminated surface. The current‐voltage (I‐V) behavior of each surface type was subsequently monitored in contact with several electrolytes.

ISSN:0003-6951    

DOI:10.1063/1.103497

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We present results on excitonic transitions and confinement at high electric fields from photocurrent and electroreflectance spectra of an In0.17Ga0.83As/Al0.3Ga0.7As strained quantum well structure fabricated into a Schottky barrier diode. Up to the highest field attained, 1.7×105V/cm, we observe a well‐defined exciton line at the band edge (in contrast to data on similar GaAs/Al0.3Ga0.7As structures), a feature important for potential optoelectronic applications. At low fields, ‘‘allowed’’ (&Dgr;n=0) transitions dominate the photocurrent spectra, but with increasing field ‘‘forbidden’’ transitions (allowed because of reduced symmetry and valence‐band mixing) grow in intensity and eventually dominate the above‐gap response. In the electroreflectance spectra, the forbidden transitions are relatively strong, even at low field. The allowed above‐gap transitions nearly vanish at low temperature because of the small field dependence of the higher lying quantum well energy levels.

ISSN:0003-6951    

DOI:10.1063/1.103498

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is demonstrated that the thickness limit of a thin nitride film which can withstand reoxidation is reduced to about 3.5 nm when it is depositedinsituon a thin‐deposited oxide film. The deposited oxide apparently provides a better surface for nitride nucleation and initial growth. Using this finding an oxide‐nitride‐oxide (ONO) film as thin as 4.6 nm was fabricated and shown to have good electrical properties and low defect density. The current leakage through the film was close to the acceptable limit in dynamic‐random‐access‐memory technology. It was also found that electron trapping is substantially higher in ONO films produced by reoxidation than in films having a top deposited oxide.

ISSN:0003-6951    

DOI:10.1063/1.103499

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe both theoretical and experimental investigations of the effects of inserting a thin, low‐doped layer into the emitter of an InP/In0.53Ga0.47As heterojunction phototransistor (HPT). This high‐low emitter structure has improved sensitivity over conventional structures at low input optical power by decreasing the bulk recombination current at the heterointerface. Experimental data show that the photocurrent gain is independent of the incident optical power at high input powers, corresponding to a heterojunction ideality factor of 1. At low input power, the gain is found to have a small power dependence, with an ideality factor of 1.25. A current gain as high as 260 is obtained at an input power of only 40 nW. These results, which are consistent with numerical simulations of the HPTs, give direct evidence that bulk recombination in the space‐charge region at the emitter/base junction is the major source of recombination current for an InP/In0.53Ga0.47As HPT.

ISSN:0003-6951    

DOI:10.1063/1.103500

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Ultraclean, integrated metal‐oxide‐semiconductor oxide fabrication has been investigated for the first time by combining (i) surface cleaning in inert ambient, (ii) wafer transfer through ultrahigh vacuum, and (iii) thermal oxidation in an ultrahigh vacuum‐based reactor. Device quality oxide structures are obtained (evidenced by dielectric breakdown characteristics for Al gate capacitors) under suitable conditions, while under other circumstances chemical mechanisms severely degrade electrical performance; even in ultraclean environments, impurity‐related Si etching reactions before oxidation degrade oxide quality, but this can be avoided by appropriate use of passivating oxide films which prevent roughness associated with etching.

ISSN:0003-6951    

DOI:10.1063/1.103501

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have observed negative differential resistance (NDR) and large peak current densities in a novel resonant interband tunneling structure grown by molecular beam epitaxy in the InAs/GaSb/AlSb material system. The structure consists of a thin AlSb barrier layer displaced from an InAs(n)/GaSp(p) interface. NDR is readily observable at room temperature with peak current densities greater than 105A/cm2. The enhancement in peak current density relative to a structure with no AlSb barrier is consistent with the existence of a quasi‐bound state in the region between the barrier and the InAs/GaAs interface. Furthermore, we demonstrate that by growing the AlSb layer on either the InAs or GaSb side of the interface, the quasi‐bound state can be localized in either material.

ISSN:0003-6951    

DOI:10.1063/1.103502

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Double quantum well resonant tunnel diodes are demonstrated in InAlAs/InGaAs for the first time. Peak‐to‐valley ratios of greater than 70:1 at room temperature and 125:1 below 200 K are observed.

ISSN:0003-6951    

DOI:10.1063/1.103503

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Self‐propagating explosive reactions, with a reaction front speed of about 4 m/s, have been observed in free‐standing polycrystalline Al/Ni multilayer thin films. The resultant phases and microstructures are compared with those obtained by conventional thermal annealing. We show evidence which indicates that melting occurred in the explosive reactions of films with an atomic concentration ratio of 3Al:1Ni. It is also observed that the propensity of multilayer films to undergo explosive reactions is dependent on the modulation length of the film as well as on the ambient temperature. These observations are interpreted with a simple model based on the rate balance between the rates of heat generation and heat dissipation.

ISSN:0003-6951    

DOI:10.1063/1.103504

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

When a signal at the nominal frequency of 76 GHz and a local oscillation (LO) at the frequency of a few gigahertz were both applied to a YBa2Cu3O7−yweak link immersed in liquid nitrogen, the former mixed with the harmonics of the latter giving rise to output at the intermediate frequency (IF) of about 150 MHz. The highest observed harmonic number was 51. Without exhaustive effort to optimize, the typical IF output power referred to the mixer output ranged between −103 and −112 dbm while the IF signal‐to‐noise ratio ranged between 16 and 4 db, depending strongly on the local oscillation power, the dc bias current, and the signal power. Reported in this letter are the experimental details as well as the requirements for a superconducting weak link to be a harmonic mixer.

ISSN:0003-6951    

DOI:10.1063/1.104229

出版商:AIP    

年代:1990

数据来源: AIP