摘要:

We have examined fluctuations in the tunneling current of 3.5 nm SiO2barriers for voltages in the direct tunneling regime. We find a 1/fpower law for the spectral density of the fluctuations wherefis the frequency. This 1/fnoise can be attributed to fluctuations of a trap assisted tunneling current through the oxide that causes current noise but is not evident in theI–Vcurves. We suggest that this noise may be a more sensitive probe of trap assisted tunneling and degradation in thin oxides than other measures. At voltages above a threshold of 2.5 V, we observe the reversible onset of non‐Gaussian current transients in the noise. The onset of these current transients can be related to a transition in the spacial uniformity of the tunneling current density that may result in eventual breakdown of the oxide. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117351

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Admittance spectroscopy was measured on Cu(In,Ga)(S,Se)2thin film and single crystal heterojunctions. The emission rates of defects for various near‐stoichiometric compositions follow a Meyer–Neldel rule, showing increasing attempt‐to‐escape frequencies with increasing defect depth. Defects in highly (In,Ga)‐rich material showed lower attempt‐to‐escape frequencies and follow a separate Meyer–Neldel relation. Repetitive air annealing of a CuInSe2heterojunction revealed a shift of the depth and capture cross section of an observed defect. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117352

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Photoluminescence from a Gem–Sin–Gemstructure has recently been demonstrated at room temperature by Gailetal. [Appl. Phys. Lett.66, 2978 (1995)]. Experimental measurements have shown that this luminescence is associated with the fourfold degenerate conduction minima which lie in the plane of the interface. In this letter, we report full‐scale microscopic calculations on both perfect and imperfect structures of this type which demonstrate that these results cannot be explained either by a ‘‘zone‐folding’’ or an alloy scattering model. We propose an alternative mechanism which links the luminescence to anomalous localization at the heterointerfaces. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117353

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Indium–tin–oxide (ITO) coated on a glass plate as the transparent electrode in polymeric light‐emitting diodes (LEDs) generates some volcano‐like patterns during use especially at a higher applied electric field strength. Such an ITO damage phenomenon is independent of Joule heat, conjugation structure of the polymer, and light‐emission process, but only dependent on the applied electric field strength. The ITO damage, which results from a self‐decomposition reaction, can cause a reduction of lifetime of the device. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117354

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The magnetotransport was studied on three‐dimensional lattices of weakly coupled InSb quantum dots (QDs) for different regimes of conductivity. Classical negative magnetoresistance was observed both in high‐ and low‐temperature regimes; for the latter it is accompanied by quantum size effect. The correlation with the geometry of the dot lattice and its ordering was found. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117355

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Visible luminescence from thermal treated intrinsic Czochralski‐grown silicon is reported. Oxygen precipitates were formed in a nearly oversaturated silicon by a two‐step thermal treatment with auxiliary use of high pressures. A wide photoluminescence band peaked at about 2.3 eV is observed in those samples for which the first treatment was performed at a relatively high temperature and which show a higher amount of oxygen precipitates and oxygen related defects. Scanning electron microscopy of the best performing samples show the presence of submicron conglomerates on the surface. We have tentatively attributed the luminescence emission to the defects in the suboxide SiOxphase formed in the oxygen precipitates. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117356

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Epitaxial liftoff (ELO) of low‐temperature‐grown GaAs (LT‐GaAs) is employed to fabricate (sub)picosecond photoconductive switches on optically transparent substrates for THz applications. Glass is selected as a substrate for on‐wafer probes while sapphire is chosen for free‐space antennas. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117357

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have investigated the width dependence of Sb delta (&dgr;) doping layers grown by Si solid phase epitaxy (SPE) on the Sb surface reconstruction prior to Si deposition. Depending on the Sb adsorption conditions a 2×1 and a 2×nsurface reconstruction is observed. Measurements of crystal truncation rods and x‐ray standing waves show a drastically reduced interface roughness and a better crystal quality for &dgr; layers grown on Sb:Si(001)−2×nsubstrates in comparison to Sb:Si(001)‐2×1, which we attribute to reduced surface stress of the Sb:Si(001)‐2×nreconstruction. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117319

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Synthesis and characterization of Ba2LaNbO6which is a new substrate material for YBa2Cu3O7−&dgr;superconductor are reported. Ba2LaNbO6has a complex cubic perovskite structure (A2BB′O6) with a lattice constanta=8.60 A˚. No detectable chemical reaction between YBa2Cu3O7−&dgr;and Ba2LaNbO6was observed even under severe heat treatment. The dielectric constant and loss factor of Ba2LaNbO6are in a range suitable for its use as a substrate for microwave applications. Superconducting YBa2Cu3O7−&dgr;–Ag thin films are growninsituon polycrystalline Ba2LaNbO6by pulsed laser ablation method. The film exhibited (00l) orientation of an orthorhombic YBa2Cu3O7−&dgr;phase. The films gave aTconset of 91 K andTc(0)of 89 K. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117320

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report that the Te donor forms a deep level and acts as aDXcenter in In1−xGaxAsyP1−y/GaAs0.61P0.39. The characteristics of Te‐related deep level is investigated by deep‐level transient spectroscopy and thermally stimulated capacitance measurements. The deep level has a thermal activation energy of 0.14±0.01 eV regardless of the alloy composition of In1−xGaxAsyP1−y. Persistent photoconductivity is observed at low temperature in all Te‐doped In1−xGaxAsyP1−y/GaAs0.61P0.39samples. The compositional dependence of deep trap density is explained by the energy difference between the conduction band minimum and theDXlevel. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117321

出版商:AIP    

年代:1996

数据来源: AIP