摘要:

Photoluminescence techniques have been used to detect and characterizep‐type conducting layers formed on the surface of semi‐insulating GaAs substrates and at the liquid phase epitaxial layer–GaAs substrate interface during pregrowth heat treatment. These layers contain ∼1017cm−3shallow acceptors and a high density of arsenic vacancy complexes, and can be eliminated by pregrowth Ga etching of the substrate.

ISSN:0003-6951    

DOI:10.1063/1.89215

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Based on a model proposed by Frisch and Patel, the dislocation velocity behavior in heavily doped germanium has been analyzed using Fermi‐Dirac statistics. Both the isothermal doping dependence and the temperature dependence of the change in dislocation velocity with doping can be accounted for by assuming an acceptorlike dislocation energy level, somewhat above the center of the energy gap.

ISSN:0003-6951    

DOI:10.1063/1.89204

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Schottky barrier diode detection in both video and mixing modes of operation has been extended to 4.252 THz (70.5 &mgr;m) using 0.5‐&mgr;m‐diam diodes fabricated from heavily doped nonepitaxialn‐type GaAs. These ultrasmall, and consequently ultralow capacitance, junctions were prepared using electron‐beam lithography and have yielded the smallest reported series‐resistance junction‐capacitance product for a Schottky barrier diode. The potential for extending diode operation to still higher frequencies is discussed.

ISSN:0003-6951    

DOI:10.1063/1.89208

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

The current‐potential characteristics ofn‐TiO2electrodes have been investigated in a photoelectrochemical cell. Photoresponse induced by the light of energy lower than the band gap of TiO2has been observed in the potential range between −1.0 and −1.4 V vs SCE in 1NNaOH. The photoresponse, which is sensitive to the oxygen gas dissolved in solution, has been attributed to some surface states at the TiO2‐electrolyte interface.

ISSN:0003-6951    

DOI:10.1063/1.89209

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A laser light‐scattering technique for measuring the relative particle concentration in a turbulent mixing field is described. The effects of ambiguity noise and optical path attenuation noise on the measurement of concentration fluctuations with this technique are discussed. Measurements of the admixture spectra in a turbulent jet show good agreement with those obtained using hot wires.

ISSN:0003-6951    

DOI:10.1063/1.89210

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A magnetically alterable phase grating integrated optic coupler‐modulator was formed utilizing the magnetic stripe domains in a LPE film of BixYb3−xFe5O12. Light was coupled to a glass waveguide and 72% intensity modulation was achieved.

ISSN:0003-6951    

DOI:10.1063/1.89211

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Photoluminescence measurements at 4.2 °K were used to study the emission behavior and the annealing characteristics in Mg‐ion‐implanted layers in GaAs. Radiative recombination due to the donor‐acceptor pairs and free electrons with holes bound to acceptors involving Mg was observed. The ionization of Mg is esti mated to be 28±2 meV. The donor‐acceptor pair band shows a large energy shift with the change of the excitation intensity. Annealing at the temperatures 750–900 °C sufficient to optically activate Mg ions implanted and to recover from lattice damages.

ISSN:0003-6951    

DOI:10.1063/1.89212

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A newly developed technique for directly measuring fiber dispersion in the frequency domain as a function of wavelength is described. A number of germanium‐ and boron‐doped fibers have been examined. The least dispersive borosilicate graded‐index fiber has a 1‐dB bandwidth of 1 GHz, after 1.07 km of propagation at &lgr;=908 nm. Frequency domain measurements were inverted into the time domain after assuming that the phase of a power transfer function could be calculated from its amplitude spectrum.

ISSN:0003-6951    

DOI:10.1063/1.89213

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Direct nuclear pumping of3He‐Xe and3He‐Kr has been achieved using the volumetric3He(n,p)3H nuclear reaction. Lasing occurred at 2.027 &mgr; and near 2.5 &mgr; in Xe I and Kr I, respectively. The Xe transition has the lowest lasing flux threshold to date, 4×1015n/cm2 sec. Scaling with both thermal flux and total pressure has been investigated.

ISSN:0003-6951    

DOI:10.1063/1.89214

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

This letter analyzes a suggested technique for studying excited atomic or molecular states on a picosecond to subpicosecond time scale by using tunable laser beams, without requiring ultrafast laser pulses or optical detectors. In the proposed technique the frequency transform of the impulse response of an excited state is determined by measuring the diffraction of a cw probe laser beam from a moving excited‐state grating induced by two intersecting tunable excitation beams, as the frequency difference between the two cw excitation beams is varied.

ISSN:0003-6951    

DOI:10.1063/1.89216

出版商:AIP    

年代:1977

数据来源: AIP