摘要:

The relaxation of strain in compositionally step‐graded InxGa1−xAs layers grown on GaAs(001) has been examined with cathodoluminescence (CL) wavelength and linearly polarized imaging approaches. A polarization anisotropy in CL is found, and this correlates with spectral shifts in the peak positions of excitonic luminescence. Varying asymmetries in misfit dislocation densities from transmission electron microscopy are found to be consistent with the &mgr;m‐scale spatial variations in strain that is deduced from the CL. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113414

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

High‐quality In0.5Ga0.5P and In0.5Ga0.5P0.99As0.01epitaxial layers on the GaAs (100) substrate have been grown by liquid phase epitaxy (LPE). Special attention is paid to the deep level transient spectroscopy (DLTS) and transient photoresponse in these samples. It is found that the epitaxial layers grown under the optimum P vapor pressure are free from deep levels and show a much longer photocarrier lifetime. We suggest that the deep level may be attributed to interstitial P atoms. From the photocarrier lifetime of different samples, we can conclude that the interstitial P atoms act as recombination centers. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113415

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Infrared detection was accomplished with the narrow bandgap semiconductor (∼0.1 eV), ReSi2. Photoresistors were fabricated from a polycrystalline ReSi2film grown on a silicon substrate. A light‐induced decrease in resistance was observed, which was due both to film photoconductivity and to a light‐sensitive contact resistance. The relative spectral response (measured at 10 K) in the wavelength range from 3000 to 6000 nm roughly follows the number of photons absorbed as estimated from the optical absorption coefficient of ReSi2. Thus, the sample is aquantum, rather thanthermal, detector. The mechanism of detection is believed to be the intrinsic band‐to‐band photogeneration of excess free carriers, leading to photoconductivity and to the reduction in contact resistance. It is suggested that ReSi2offers the potential for a new intrinsic semiconductor infrared detector technology, which may be integrated on a silicon chip, and whose absorption edge is well into the far‐infrared range. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113416

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effects of Ti deposition temperature on the resistivity of as‐deposited films are reported. The microstructure of as‐deposited Ti films and its effect on electrical properties of TiSixformed during subsequent thermal annealing are investigated. Our work shows that the film deposition temperature not only affects the resistivity of as‐deposited film but also influences the resistivity of TiSixformed during thermal anneals. The microstructure, specifically the grain size, of as‐deposited Ti films appears to be the controlling factor in formation of TiSixphases. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113417

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Room temperature electroluminescence efficiency as a function of forward bias voltage,VF, shows that there are two recombination regions in device qualitya‐Si:H diodes. The recombination threshold voltage,Vt1, is 0.48–0.49 V. The transition voltage,Vt2, is 0.7–0.8 V. WhenVt1<VF<Vt2the electric field strongly enhances the luminescence efficiency, whenVF≳Vt2the luminescence efficiency is almost independent of the electric field. The increase of the EL efficiency in the low injection regime depends on the competition of radiative and nonradiative recombination. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113418

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report transport measurements on a series of high purity InAs epilayers grown on GaAs substrates by metalorganic chemical vapor deposition using tertiarybutylarsine and trimethylindium. Perfectly specular surfaces were obtained by a two step growth method consisting of a 400 °C prelayer followed by deposition of the thick bulk layer at higher growth temperatures. Temperature dependent Hall measurements between 1.8 and 293 K showed a competition between bulk and surface conduction, with average Hall mobilities of up to 1.2×105cm2/V s at 50 K. Large changes in the temperature dependent transport data are observed several hours after Hall contact formation and appear to be due to passivation of the surface accumulation layer by native oxide formation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113419

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A multistep postannealing scheme has been developed for preparing nearly single phased,c‐axis oriented TlBa2Ca2Cu3Ox(Tl‐1223) superconducting thin films fabricated by the direct‐current‐sputtering process. Films obtained by the present process have shown, for the first time in this system, a critical current density (Jc) above 106A/cm2at 77 K with a zero‐resistance transition temperatureTc0≊110 K. The order of magnitude enhancement inJcis attributed to the improvement of film morphology which, in turn, removed most of the weak links encountered previously. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113420

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new method is developed using a transparent indicator ferrimagnetic magneto‐optic film with in‐plane anisotropy for visualization and direct experimental study of dynamic magnetization processes and nondestructive characterization of the defect structure of magnetic multilayers. Some examples of its application to the investigation of peculiarities of the as‐grown magnetic structure of electrochemically produced CoNiCu/Cu multilayers with a giant magnetoresistance (GMR) effect and magnetization reversal by domain wall motion are described. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113421

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

To date diamond films grown with the combustion technique have used either acetylene or, rarely, ethylene as the fuel. However, there are barriers to large scale commercialization of the combustion technique using either fuel. For example, acetylene is relatively expensive and difficult to handle, while the use of ethylene gives relatively low growth rates. In this letter we propose replacing acetylene with MAPPTMgas, a commercial mixture of methyl acetylene and propadiene in liquefied petroleum gas (primarily propylene). MAPP gas is considerably cheaper, safer, and easier to handle than acetylene. Furthermore, the experiments described here suggest that MAPP gas flames are only slightly less efficient than acetylene flames at converting fuel carbon atoms into diamond. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113422

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electroluminescence coupling between the wells in multiple quantum well (MQW) structures is taken into account to show how, if the emissivity of one well equals its absorptivity, then, the emissivity of the whole structure also equals its absorptivity. This result is used to critically analyze previously reported results in which the limiting efficiency of MQW solar cells were supposed to exceed the limiting efficiency of single bandgap solar cells.

ISSN:0003-6951    

DOI:10.1063/1.113423

出版商:AIP    

年代:1995

数据来源: AIP