摘要:

A new bar cathode system that is simple and easy to construct was developed. Its characteristics were investigated and compared with a conventional multipin cathode system. The result demonstrated that transversely excited CO2lasers employing both cathode systems have similar characteristics and also gave about 10 kW output, although oscillation mode patterns of both systems differed a little from each other. The studies showed that we should be able to get a uniform gain distribution and a uniform oscillation mode with a cathode system consisting of variously shaped bars.

ISSN:0003-6951    

DOI:10.1063/1.97011

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A novel triple layer film is described which provides single mode propagation in a magneto‐optically active waveguide of convenient thickness. All three layers are modified yttrium iron garnet (YIG) films grown by liquid phase epitaxy on a gadolinium gallium garnet substrate. The top film is the active layer, several microns thick. The middle layer is similar but it has a slightly smaller refractive index to assure single mode operation of the top layer. The bottom layer has high optical absorption to eliminate all of the higher order modes which are propagated in the triple layer and a slightly higher refractive index to prevent the confinement of any modes to the top two low loss layers. Using a praseodymium YIG film as the absorbing layer, 17 TE modes were propagated at 1.51 &mgr;m where the Pr absorption is low but only the TE0mode was observed at 1.48 and 1.54 &mgr;m where the Pr absorption is high. Such triple layer garnet films will be useful in all magneto‐optic waveguide devices.

ISSN:0003-6951    

DOI:10.1063/1.96489

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The first device performance of GaAs/AlxGa1−xAs double‐heterostructure lasers grown by chemical beam epitaxy (CBE) is reported. Very low averaged current threshold densities of ∼500 A/cm2were obtained for wafers with active layer thicknesses of ∼500–1000 A˚ and confinement layers of Al0.5Ga0.5As. Such current threshold densities were similar to those obtained from the best wafers grown by other techniques. This unequivocally established that CBE is capable of producing high optical quality multilayer heterostructures. Further, extreme device uniformity was also obtained.

ISSN:0003-6951    

DOI:10.1063/1.96490

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

In certain problems of electrical transport through condensed matter, it is important to know the potential distribution with microscopic resolution, e.g., at interfaces (Schottky barriers) orpnjunctions. Scanning tunneling potentiometry, a new application of scanning tunneling microscopy, is capable of providing this information. The tunnel current is used for simultaneously sensing probe‐to‐sample distance and local potential. The method was tested with a gold‐island metal‐insulator‐metal structure.

ISSN:0003-6951    

DOI:10.1063/1.96491

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A method for determining the dominant diffusing constituent in a binary amorphous alloy is demonstrated with the Ni‐Zr system. Nickel is the dominant moving species in an amorphous Ni‐Zr alloy near thea‐Ni50Zr50composition at 250 °C. In comparison to the Ni, the Zr has a negligible mobility under similar thermodynamic driving forces. Rutherford backscattering spectrometry is used to measure the change in the concentration of a thin film of Ni between thick amorphous layers. Based upon the change in the Ni profile, the diffusivity of Ni in an amorphous Ni‐Zr alloy is between 1×10−17and 1×10−16cm2/s at 250 °C.

ISSN:0003-6951    

DOI:10.1063/1.96492

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Sputtering of a magnesium target with a beam of argon ions in the presence of a partial pressure of reactive oxygen gas has been found to yield smooth MgOxthin‐film dielectrics with low electrical loss, good mechanical stability, and excellent reproducibility. The films consist of polycrystalline MgO with a grain size ≲50 A˚ and an OH‐containing component. The thickness dependence of the areal capacitance is discussed in the context of a two‐layer model in which this oxygen‐rich phase (x&bartil;1.4) overlays a thin (≲40 A˚) stoichiometric phase (x&bartil;1.0). Observation of superconducting tunneling characteristics in trilayer Au‐MgOx‐Pb structures confirms pinhole‐free coverage which may have possible application as artificial tunnel barriers.

ISSN:0003-6951    

DOI:10.1063/1.96493

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Specular CdTe epitaxial layers have been grown on (100) Si substrates by the low pressure metalorganic chemical vapor deposition method with dimethylcadmium (DMCd) and diethyltelluride (DETe) source materials. Auger electron spectroscopy and scanning electron microscopy have been used to demonstrate the uniform composition, good surface morphology, and abrupt interface between the CdTe layer and the silicon substrate. The dominant sharp bound exciton related emission peak at 1.593 eV and the weak defect related extrinsic band at 1.483 eV were observed in the 14 K photoluminescence spectra, demonstrating that high quality CdTe epitaxial layers can be grown on Si at 375 °C with the DMCd/DETe mole ratio at approximate unity.

ISSN:0003-6951    

DOI:10.1063/1.96494

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Narrowband photosignals with quantum efficiencies up to 30% are observed on Al‐SiO2‐p‐Si junctions. The frequency selective photosignals are due to surface plasmon polaritons confined to the metal‐air interface excited by grating coupling. The best results are achieved with Ag‐Al‐SiO2‐p‐Si junctions providing a 12‐nm linewidth and a signal to background ratio of 7:1 at a wavelength of 632.8 nm. The spectral sensitivity of these photodetectors is tunable over the whole visible spectrum either by a variation of the tilt angle or by a dielectric coating.

ISSN:0003-6951    

DOI:10.1063/1.96495

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

ZnSe films have been grown by molecular beam epitaxy for the first time on argon ion sputtered and annealed (100) Si substrates, the simultaneous sputtering and annealing process being performed at a substrate temperature of 400 °C. The sputtered and annealed Si substrates were atomically clean as determined by Auger electron spectroscopy analysis, and exhibited a streaky, reconstructed (2×1) reflection high‐energy electron diffraction (RHEED) pattern. Films grown with both the constituent element (Zn and Se) fluxes set to provide a growth rate of ∼0.6 &mgr;m/h at initiation of growth were polycrystalline, the crystallites being strongly oriented in the [111] direction as determined by RHEED observations. Parallel epitaxy, i.e., (100) ZnSe∥(100) Si was achieved when the growth rate at initiation of growth was close to zero. Epitaxial ZnSe films exhibited dominant bound excitonic 4.2 K photoluminescence (PL) emission at 2.788 eV (Iz1). TheIz1peak was also detected in the PL spectra of polycrystalline films; however, its absolute intensity was reduced by over two orders of magnitude.

ISSN:0003-6951    

DOI:10.1063/1.96496

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Ion beam synthesis of a buried SiO2layer is an attractive silicon‐on‐insulator technology for high‐speed complementary metal‐oxide‐semiconductor circuits and radiation hardened devices. We demonstrate here a new annealing procedure at 1405 °C that produces silicon films of excellent quality, essentially free of oxygen precipitates and with sharp interfaces between the Si and the SiO2. Buried oxide layers have been formed in Si (100) wafers by implanting 400 keV molecular oxygen at 500 °C to a dose of 1.8×1018cm−2. Annealing was performed by radiative heating of the back side of each sample to the melt temperature of silicon,TM=1412 °C, so that the buried oxide structure was at 1405 °C. The temperature control relies entirely on the change in optical properties of silicon upon melting. This ensures, without any external feedback, that the surface exposed to the photon flux will remain atTM.

ISSN:0003-6951    

DOI:10.1063/1.96497

出版商:AIP    

年代:1986

数据来源: AIP