摘要:

The device performance of graded barrier quantum well laser diodes with various buffer layer structures grown by metalorganic chemical vapor deposition has been studied. Devices having four structures (a GaAs buffer layer only, a compositionally graded buffer layer, a superlattice buffer layer, or both a graded and a superlattice buffer layer) have been characterized. In contrast with similar studies involving laser devices grown by molecular beam epitaxy, little variation in device performance is observed. These data indicate that the quality of AlGaAs‐GaAs heterostructures for optical devices may be dependent on the details of the method used for the epitaxial growth of the layers.

ISSN:0003-6951    

DOI:10.1063/1.98231

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

In pulse power driven free‐electron laser experiments for a diode voltage 300–600 kV, a maximum electron beam current 730 A, with a 110‐ns width of beam voltage pulse and a helical wiggler with a pitch of 2 cm, the temporal evolution of radiation spectra is observed. The frequency variations are explained theoretically by using instantaneous values of beam voltages and currents. In the calculation we take account of the variation in the beam cross section of the beam voltage drop and the wiggler field. The spatial growth rate of the radiation power was also measured. The observed growth rate is 1 dB/cm and the saturation level is 250 kW with the spector peak at 58 GHz.

ISSN:0003-6951    

DOI:10.1063/1.98232

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We present direct measurement of low propagation loss in InP‐core antiresonant reflecting optical waveguides (ARROW’s) at wavelengths that are strongly absorbed in the directly adjacent InGaAsP reflector layers. With 1.54‐&mgr;m luminescence peak InGaAsP reflector layers, losses range from a low value of ∼0.9 dB/cm at 1.67 &mgr;m to ∼6.5 dB/cm at a wavelength of 1.515 &mgr;m for which the reflector layer losses approach 104dB/cm. This proves the suitability of the ARROW geometry for providing large mode, low propagation loss guides for wavelengths that may either be generated, experience gain, or absorption within the reflector layers.

ISSN:0003-6951    

DOI:10.1063/1.98233

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Frequency response measurements are used to determine the carrier lifetime of 1.3‐&mgr;m InGaAsP buried heterostructure lasers between 1 mA and threshold. The data confirm previous results on the radiative and Auger recombination coefficients and reveal the presence of a nonradiative current which dominates at low currents and contributes 4 mA at threshold.

ISSN:0003-6951    

DOI:10.1063/1.98234

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A high power, compact axial flow CO2laser is described with a power output of 3.5 kW and a discharge length of 0.6 m using an unfolded cavity. The high power per unit length is achieved by the use of multiple electrodes with gas injection through porous anodes. Discharge currents of more than 2 A and cavity diameters up to 150 mm have been used with 12 anodes without the glow to arc transition occurring. An electrical to optical conversion efficiency of 23% has been achieved. The results indicate the effect of the current density and degree of turbulence in the transition regions of the discharges adjacent to the anodes in offsetting the glow to arc transition.

ISSN:0003-6951    

DOI:10.1063/1.98235

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The dynamics of an ionic sheath submitted to a periodic field with a frequency between the ionic and the electronic plasma frequencies is analyzed under one‐dimensional, noncollisional, and thick sheath assumptions. Accordingly the displacement current is calculated.

ISSN:0003-6951    

DOI:10.1063/1.98236

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Laser induced fluorescence has been used to detect ground‐state CF and CF2radicals in a CF4/O2plasma etching reactor. Measurements are reported of the spatial variation of CF2concentrations, of the CF radical rotational state distributions, and of the variation of both species with O2content of the plasma.

ISSN:0003-6951    

DOI:10.1063/1.98214

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Differential infrared spectroscopy has been used to study the silicon‐oxygen stretching band of thin silicon dioxide films thermally grown on single‐crystal silicon. We consistently observe an asymmetry in the spectra of films thicker than about 100 A˚, of about 9 cm−1. The peak position, width, and degree of asymmetry are also found to be sensitively dependent upon film thickness below 100–150 A˚, while above this level these features are only very weakly dependent upon film thickness, indicating the presence of a thin layer of different structural or bonding properties. Our interpretation suggests that the infrared spectra of layers up to 100 A˚ thick are significantly affected by strain originating at the silicon‐oxide interface, in agreement with recent observations.

ISSN:0003-6951    

DOI:10.1063/1.98187

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Raman scattering as a technique for studying the formation of tungsten silicide is presented. The tungsten silicide films have been formed by rapid thermal annealing of thin tungsten films sputter deposited on silicon substrates. The Raman data are interpreted by using data from resistivity measurements, Auger and Rutherford backscattering measurements, and scanning electron microscopy.

ISSN:0003-6951    

DOI:10.1063/1.98188

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Energy‐band discontinuities were measured for hydrogenated amorphous silicon and crystalline silicon heterojunctions by internal photoemission. The measurement was performed both for the conduction‐band side and for the valence‐band side, and the conduction‐band discontinuity and the valence‐band discontinuity were estimated to be 0.09 and 0.71 eV, respectively. This result indicates that the band discontinuity mainly exists at the valence‐band side.

ISSN:0003-6951    

DOI:10.1063/1.98189

出版商:AIP    

年代:1987

数据来源: AIP