摘要:

A new method for tunable detection and generation of terahertz phonons is reported. It is based on our observation that the lowest energy level of excited Eu2+ions in CaF2and SrF2crystals can be split by uniaxial stress into two levels with a variable separation up to 2.4 THz. Phonons are generated by one‐phonon relaxation between these levels and detected by phonon‐induced fluorescence radiation from the upper level. The detector is applied to study the spectral distribution of phonons generated by the heat‐pulse technique.

ISSN:0003-6951    

DOI:10.1063/1.90855

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

A simple method of preparing plasma‐grown anodic oxide on GaAs with improved physical and electrical properties is described. A GaAs surface was sputtered by positive oxygen ions prior to the plasma anodization, resulting in a Ga‐rich oxide layer on the surface. The oxide formed through this Ga‐rich layer had a low pin hole density and exhibited high breakdown voltages (3×106V/cm) and less hysteresis in MOS‐deviceC‐Vcharacteristics.

ISSN:0003-6951    

DOI:10.1063/1.90856

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The annealing of indium‐implanted thin epitaxial films of Pb0.8Sn0.2Te (LTT) by means of pulses from aQ‐switched CO2laser is reported. The results of the annealing are studied by channeling and interference‐contrast microscopy. The annealing seems to proceed through the melting‐liquid phase recrystallization mechanism which leads to crystals of quality similar to those obtained by conventional furnace annealing. Interference phenomena, related to the fact that the wavelength of the laser radiation is comparable to the film thickness, are observed.

ISSN:0003-6951    

DOI:10.1063/1.90857

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The adsorption of oxygen on a Si (111) surface is accompanied by significant changes in the local electronic densities of states. These effects have been monitored as changes in the spectral distribution of emittedL2,3VVAuger electrons from pure and oxygen‐covered surfaces. Oxygen coverages varying from 0 to slightly below monolayer coverage (237L) have been employed. The present results are compared with data from recent sputter‐profiling studies of the Si‐SiO2interface, showing similar behaviors in the two types of experiments.

ISSN:0003-6951    

DOI:10.1063/1.90858

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Drastic long‐term changes of transport properties and the recombination behavior of a Hg1−xCdxTe crystal are reported. Being puren‐type material immediately after fabrication the crystal showed ap‐type conduction after a five‐year storage under room‐temperature conditions. The lifetime—formerly dominated by Auger recombination—dropped by about two orders of magnitude. A model of Hg vacancy diffusion is suggested to explain the observed data.

ISSN:0003-6951    

DOI:10.1063/1.90859

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The band‐edge effective mass for conduction electrons in GaxIn1−xAsyP1−yhas been determined for several different alloy compositions covering the complete range of alloys grown lattice‐matched on InP. Measurements show that the effective mass varies nearly linearly with alloy composition.

ISSN:0003-6951    

DOI:10.1063/1.90860

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We report the development of infrared photoconductive detectors which are background fluctuation noise limited at photon fluxes ≲108s−1. The detectors were fabricated from germanium doped with 2×1014cm−3gallium. Detectors operated in the conventional manner atT=3 K showed significant photoconductive response for wavelengths out to 120 &mgr;m with a minimum NEP of 2.4×10−17W Hz−1/2at 94 &mgr;m. Detectors operated atT=2 K with a uniaxial stress of 60 kgf mm−2applied along a [100] direction showed significant response to 205 &mgr;m and gave a minimum NEP of 5.7×1017W Hz−1/2at ≈150 &mgr;m. The stressed detectors are four orders of magnitude more sensitive than any previous photoconductor beyond 120 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.90861

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Fluorescence decays for the Nd3+ : 4F3/2→4I11/2transition at 1.06 &mgr;m and the Tb3+ : 5D4→7F5transition at 545 nm were studied, using the vapor‐phase carrier chelate 2,2,6,6‐tetramethyl‐3, 5‐heptanedione and pulsed‐laser excitation, as functions of (1) ground‐ and excited‐state molecular densities and (2) local temperature. In each case, inferred excited‐state densities 1016–1017cm−3were sustained for times greater than several hundred nanoseconds.

ISSN:0003-6951    

DOI:10.1063/1.90841

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Response of a Pockels readout optical modulator to x rays has been measured. Sensitivity data and results of cursory imaging experiments suggest novel applications such as on‐line radiography.

ISSN:0003-6951    

DOI:10.1063/1.90842

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Laser operation (4.2–300 °K) of multiple‐quantum‐well AlxGa1−xAs‐GaAs heterostructures on a phonon (LO) sideband ∼36 meV below the lowest confined‐particle transitions is described. Phonon‐sideband laser data are presented on two different metalorganic chemical‐vapor‐deposited (MO‐CVD) quantum‐well heterostructures with four GaAs active regions (Lz∼50 and ∼90 A˚) coupled by three AlxGa1−xAs (x∼0.35) barriers.

ISSN:0003-6951    

DOI:10.1063/1.90843

出版商:AIP    

年代:1979

数据来源: AIP