摘要:

The effects of plasma surface treatment, usingN2Ogas, ofBa0.5Sr0.5TiO3(BST) film on the leakage current characteristic of a Pt/BST/Pt capacitor were investigated. As a result of exposure of BST film to the plasma, the leakage current density of the BST capacitor decreased by two orders of magnitude in the high voltage region, and higher onset voltage of an abrupt increase in leakage current was observed. The improvement of leakage properties of BST films can be attributed to the elimination of the bulged curve in the leakage current characteristics. Thermal desorption spectroscopy showed that the elimination was closely related to the reduction of carbon content in the BST film. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.120296

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The dependence of the near-band edge and the yellow luminescence inn-type GaN grown by organometallic vapor-phase epitaxy is investigated as a function of doping concentration. The band edge and yellow luminescence intensity increase as the doping concentration is increased. However, the band-edge-to-yellow luminescence ratio does not change significantly as the doping concentration is increased by two orders of magnitude. A theoretical model based on rate equations is developed for the band-edge-to-yellow intensity ratio. Analysis of the experimental data in terms of the model reveals that the concentration of the level causing the yellow luminescence increases linearly with doping concentration. This dependence shows that the yellow luminescence is due to a compensating center. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120297

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present high-resolution x-ray diffraction studies describing the evolution of the strain relaxation phenomena in a strained InGaAsP surface grating resulting from burying in InP. We have compared reciprocal space maps of symmetrical and asymmetrical reflections from free-strain gratings, strained surface gratings, and strained buried gratings. After burying, modifications in the coherently and diffusely scattered intensity have been observed indicating the counteraction of the embedding material to the laterally nonuniform strain relaxation, which occurs in free-surface (nonburied) strained grating. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120298

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Experimental and theoretical investigations are reported for defect generation by electrical stress in silicon dioxide and for the critical number of defects necessary to trigger destructive breakdown. Experimental evidence is presented showing that the critical number of defects reaches a limit when the oxide thickness is reduced below 2.7 nm. Percolation calculations are shown to be consistent with this oxide thickness limit representing the “effective size” of one defect spanning the oxide, connecting anode and cathode together. Also, these calculations show that not all of the defects are capable of triggering a destructive breakdown event. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120299

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The organization of coherent three-dimensional islands during the growth of SiGe/Si multilayers on Si(100) was investigated with cross-sectional transmission electron microscopy. Merging of islands of different initial size is found to be the dominant mechanism leading to a uniform size distribution. Upon overgrowth with Si, we observe a change of the shape of the islands from the {105}-faceted “hut” to a boxlike shape bounded on top by a (100) facet. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120300

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Dielectric polarization noise in siliconp-njunctions was measured at low leakage current, less than1×10−17 A,and at temperatures between 110 and 200 K. The power spectra of the noise voltages exhibit1/fcharacteristics, wherefis the frequency. The dielectric loss of thep-njunctions, which was derived from the1/fnoise by using the fluctuation-dissipation theorem, is proportional to the temperature, and is almost independent of the characteristics of thep-njunctions. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120301

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Strained epitaxy has been shown to produce high quality InAs/GaAs quantum dot structures by single step epitaxy. While effective mass-based approaches have been used for quantum structures, the nature of the strain and quantum confinement in self-assembled dots is such that this is not a good approximation. In this letter, we use an eight-bandk⋅pformalism to find the electronic spectra in InAs/GaAs dots. The eight-band model shows that, in agreement with experiments, there are indeed several bound states in the conduction band well. Our results show that the simpler effective mass approaches cannot be used to quantitatively examine the physics of intersubband devices based on self-assembled quantum dots. Intersubband optical matrix elements and Coulomb blockade energy are also calculated in this letter. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120302

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A methylene dihydropyridine with a high ground-state dipole moment was investigated to explore the possibility of using it to form an organic monomeric glass “electret” film. Measurements were done in a specially designed test cell. An electric field was applied to a 100-&mgr;m-thick film of dihydropyridine while cooling from a melt. The cell potential was recorded as a function of time to study the homocharge and polarization relaxations. The homocharge relaxation time was≈900 s.The polarization relaxation time was≈2×105 sin the vicinity of the glass transition temperature. The polarization is linear over a wide range of electric field strength. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120303

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We report on optoelectronic switching devices with high photoconductive gain which are sensitive to the polarization direction of the optical input. Due to the large polarization anisotropy of the absorption coefficient of ordered GaInP, an electrical output can be switched “on” and “off” by rotating the linear polarization of the input light. Depending on the external adjustment of the working point, the structure can operate as a polarization threshold switch or a polarization detector, respectively. First results exhibit a switching contrast of 25 dB and a contrast of the detector signal of 7 dB between two perpendicularly polarized incident light beams, respectively. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120304

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The use of nitrogen as the carrier gas in metalorganic chemical vapor deposition (MOCVD) for the growth of carbon-doped GaInP/GaAs heterojunction bipolar transistors (HBTs) is reported. The material quality grown using a nitrogen carrier gas is the same as that of using a hydrogen carrier gas. High carbon doping and hole concentrations of 3×1020and 2×1020cm−3in GaAs were obtained. The fabricated HBTs showed very good DC and RF performances indicating that nitrogen can be a promising carrier gas for MOCVD growth. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120305

出版商:AIP    

年代:1997

数据来源: AIP