摘要:

Optically pumped stimulated emission (SE) from InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic chemical vapor deposition has been systematically studied as a function of excitation length(Lexc).Two distinct SE peaks were observed from these structures: one that originates at 425 nm at 10 K (430 nm at 300 K) and another that originates at 434 nm at 10 K (438 nm at 300 K). The SE threshold for the high-energy peak was observed to always be lower than that of the low-energy peak, but the difference was found to decrease greatly with increasingLexc.A detailed study of the emission intensity of these two SE peaks as a function of excitation density shows that the two peaks compete for gain in the MQW active region. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122864

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Fowler–Nordheim tunneling of holes through thermally grown silicon dioxide on 6H–silicon carbide is reported. Oxides of 5.2, 10, and 14.2 nm thickness were grown on thep+face of ap+nSiC junction. Thep+njunction served to separate the electron and hole tunneling currents. Hole tunneling was found to be the dominant current mechanism through the oxide. Fowler–Nordheim analysis, using a parabolicE–Krelationship, was performed to extract a barrier height–effective mass product,&Fgr;B3/2(mox/m0)1/2,for electrons and holes of2.88&percent;±4.9&percent;and2.38&percent;±3.8&percent;(V3/2)respectively. An estimate for the effective mass of holes within the oxide was made using both the parabolic and Franz dispersion relations. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122865

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In this letter, we show the ability, through introduction of a thinSi1−x−yGexCylayer, to eliminate the enhancement of enhanced boron diffusion in silicon due to an oxidizing surface or ion implant damage. This reduction of diffusion is accomplished through a low-temperature-grown thin epitaxialSi1−x−yGexCylayer which completely filters out excess interstitials introduced by oxidation or ion implant damage. We also quantify the oxidation-enhanced diffusion (OED) and transient-enhanced diffusion (TED) dependence on substitutional carbon level, and further report both the observation of carbon TED and OED, and its dependence on carbon levels. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122866

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

To identify Ga- or Zn-related deep levels, deep level transient spectroscopy (DLTS) measurements were performed repeatedly during the elemental transmutation of67Gato67Zn.The radioactive isotope67Gawas recoil implanted intop-type 6H–SiC for radiotracer experiments. The DLTS spectra exhibit one peak of time-dependent height. It describes the increasing concentration of the daughter element Zn with the half life of the nuclear decay. Thus, one Zn-related level at 1.16 eV above the valence band edge is definitely identified. There is no deep level of Ga in the lower part of the band gap. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122867

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Using a hydrogen-terminated Si {111} surface as a substrate, we have grown Si nanowhiskers along the ⟨112⟩ direction by the vapor–liquid–solid mechanism. The minimum silicon core diameter was 3 nm and the maximum length was about 2 &mgr;m. The minimum silicon core diameter is close to the critical value for visible light emission due to the quantum confinement effect. In contrast to an oxidized Si surface, the hydrogen-terminated surface facilitates the formation of small molten Au–Si catalysts at a lower temperature (500&hthinsp;°C) which is slightly above the eutectic temperature. The formation of catalysts and the subsequent growth at the low temperature yield thin Si nanowhiskers on a Si substrate. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122868

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have studied the pressure and temperature dependence of the absorption edge of a 4-&mgr;m-thick layer of the alloyGa0.92In0.08As0.985N0.015.We have measured the hydrostatic pressure coefficient of the energy gap of this alloy to be 51 meV/GPa, which is more than a factor two lower than that of GaAs (116 meV/GPa). This surprisingly large lowering of the pressure coefficient is attributed to the addition of only ∼1.5&percent; nitrogen. In addition, the temperature-induced shift of the edge is reduced by the presence of nitrogen. We can explain this reduction by the substantial decrease of the dilatation term in the temperature dependence of the energy gap. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122869

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Normal-incident infrared absorption in the 8–12-&mgr;m-atmospheric spectral window in the InGaAs/GaAs quantum-dot superlattice is observed. Using cross-sectional transmission electron microscopy, we find that the InGaAs quantum dots are perfectly vertically aligned in the growth direction (100). Under the normal incident radiation, a distinct absorption peaked at 9.9 &mgr;m is observed. This work indicates the potential of this quantum-dot superlattice structure for use as normal-incident infrared imaging focal arrays application without fabricating grating structures. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122870

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

An ultrathin, 1–6 monolayers (MLs) thick, Si &dgr; layer, is embedded in bulk GaAs. The normally observed self-assembling with resulting phase separation can be avoided until &dgr;-layer thickness of 4 MLs, which opens the possibility to study two-dimensional (2D) properties of this III–V/IV heterostructure. Optical, electrical, transport, and structural characterization of the Si &dgr; layer has been carried out. In luminescence, two novel emission bands are observed, which are blueshifted as the width of the Si &dgr; layer is reduced, indicating pronounced 2D properties. The derived results on transition energies and electronic structure are compared with theoretical predictions obtained by a self-consistent approach. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122871

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report the fabrication and testing of a silicon-based tunnel diode structure that incorporates a multilayer tunneling dielectric. The barrier consists of two thermally grown silicon oxide layers of direct tunneling thickness, ∼3.5 nm each, separated by an ultrathin nanocrystalline silicon layer approximately 5 nm thick. The diode displays current–voltage characteristics that are similar to those of a Fowler–Nordheim device, with a strong current turn-on beyond threshold positive and negative biases, and a “window” region between these two levels where charge transport across the barrier is negligible. In contrast to Fowler–Nordheim devices, the barrier does not appear to degrade significantly when biased in either of its conduction regimes. This property is attributed to the intrinsic degradation resistance of direct tunnel oxides. Additionally, capacitance–voltage characteristics show that the structure is of high quality. Because of its current–voltage and endurance capabilities, this structure shows promise for nonvolatile memory and other applications which require improved endurance and charge retention. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122872

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We demonstrate that bulk GaAs irradiated by heavyAu+ions shows efficient saturable absorption with subpicosecond recovery time and without any relaxation rate saturation up to excitation densities as high as1.6 mJ/cm2.A comparison with other types of ion irradiation shows that heavy-ion-irradiated GaAs is a very promising material for ultrafast optoelectronics and optical processing at high repetition rates. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.122873

出版商:AIP    

年代:1998

数据来源: AIP