摘要:

Double positioning boundaries on {12¯10} and {11¯00} planes in wurtzite GaN epilayer grown by molecular beam epitaxy on {1¯1¯1¯}B GaP are described. Transmission electron microscopy observations demonstrate that the {12¯10} boundary extending a short distance along thecaxis is characterized by a displacement of 1/2⟨101¯1⟩ and is associated with single growth faults in the basal plane. This boundary forms as a consequence of island coalescence. Conversely, the {11¯00} boundary originates at the epilayer/substrate interface and runs through the whole epilayer, whileg.Ranalysis combined with high resolution electron microscopy suggests a displacement of1/3n⟨112¯0⟩(n>3)in the basal plane with an additional shift along⟨0001⟩of1/n⟨0001⟩(n>3). ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118520

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The near band edge photoluminescence (PL) of cubic GaN epilayers grown by radio frequency (rf) plasma-assisted molecular beam epitaxy on (100) GaAs is measured. Since the PL is excited with an unfocused laser beam it resembles thelayerproperties rather than the properties of micron-size inclusions or micro crystals. The low temperature PL spectra show well separated lines at 3.26 and 3.15 eV which are due to excitonic and donor-acceptor pair transitions (donor binding energy 25 meV, acceptor binding energy 130 meV). No emission above the band gap of the cubic phase is detected. PL results are confirmed by x-ray diffraction and atomic force microscopy which reveal only negligible contributions from hexagonal inclusions and micron size single crystals. The room temperature PL consists of an emission band at about 3.21 eV with a full width at half maximum of 117 meV. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118521

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

CdTe layers were grown by metalorganic vapor phase epitaxy (MOVPE) on different substrates like sapphire, GaAs, and CdTe wafers. The growth was carried out at the temperature 340 °C and time in the range of 2–4 h using dimethyl-cadmium and diisopropil-tellurium as precursors. The layers were studied by scanning electron microscopy, Rutherford backscattering spectroscopy, and high resolution low-temperature photoluminescence spectroscopy. The surface morphology and RBS and PL spectra of CdTe MOVPE layers are reported and the substrate effect on the layer properties is demonstrated. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118522

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Dislocation glide velocities in GaAlAs/GaAs, InGaAsP/InP, and GaN-based light-emitting devices are estimated. These results are consistent with device degradation rates related to dislocation motion. It is clarified that the long lifetime of GaN-based devices with high dislocation density is principally due to extremely small dislocation mobility, partly due to small shear stress for dislocation motion, and due little to the radiation enhancement effect. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118523

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A new geometrical configuration for superconductive tunnel junctions as high energy resolution particle detectors is presented. The proposed configuration is based on annular junctions, in which fluxons are trapped in the central hole during the superconducting transition. Such a configuration overcomes some important drawbacks of the traditional geometries. The suppression of the Josephson critical current by a magnetic field that does not need to be sustained during the whole detection time and the absence of Fiske steps, which compromise the stability of the bias point, are automatically reached with the new configuration. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.119322

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

It is demonstrated that it is possible to image magnetic domains with a resolution of better than 60 nm with the Kerr effect in a reflection-mode scanning near-field optical microscope. Images taken of tracks of thermomagnetically prewritten bits in a Co/Pt multilayer structure magnetized out-of plane showed optical features in a track pattern whose appearance was determined by the position of an analyzer in front of the photomultiplier tube. These features were not apparent in the topography, showing this to be a purely magneto-optic effect. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118524

出版商:AIP    

年代:1997

数据来源: AIP