摘要:

Stimulated oxidation of InP (100) surfaces by primary electron beams was studied by Auger electron spectroscopy. At the point of impact of the incident beam, we concluded that the formation of indium oxide and of a volatile phosphorus oxide occur, which explains the phosphorus depletion of the first monolayers. The low‐energy electron‐diffraction patterns for successive heat treatments and electron‐stimulated oxidations of InP surfaces, and the corresponding characteristic‐energy‐loss spectra were performed. For heat treatments close to the decomposition temperature, we report here on how low‐energy‐loss spectroscopy was used to supply the deficiency of Auger electron spectroscopy, the latter method being unable to detect the formation of indium microdroplets.

ISSN:0021-8979    

DOI:10.1063/1.328378

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Thermal field emission of electrons has been investigated from a tungsten field emitter illuminated by the focused beam of a laser operating at a range of wavelengths in the visible region of the spectrum. The temperature rise of the tip is determined as a function of the displacement of the focused spot of light along the shank, and of its polarization. The experimental data are compared with the results of a first‐principle calculation of the temperature rise, based on an experimental investigation of the intensity distribution within the focused spot of light and of the geometry of the field emitter. The comparison shows that when the laser beam is focused close to the tip the temperature rise is anomalously large; evidence is presented which suggests that the temperature rise of the tip is substantially enhanced by diffraction effects.

ISSN:0021-8979    

DOI:10.1063/1.328379

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Thermal oxidation of InP and properties of oxide films have been studied. Surface orientation dependence of the oxidation rate can be explained by orientation dependence of bond density available for reaction with oxygen molecules. The activation energy of the parabolic rate constant is 2.06 eV, which may be attributed to the value for oxygen diffusion through InP oxide. From the electron diffraction and infrared absorption measurements, it is found that the oxide film is composed of polycrystalline InPO4(In2O3+P2O5) and that oxides thermally grown at high temperatures, above 620 °C become In rich and form lower oxides, such as In4O2and In2O, owing to phosphorus evaporation. Resistivities of the thermally grown oxide films at room temperature range from 108to 109&OHgr; cm and decrease with an increase in oxidation temperature and time, which may be mainly caused by lack of P2O5in the oxide film.

ISSN:0021-8979    

DOI:10.1063/1.328380

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A quartz crystal microbalance technique was used in conjunction with Auger electron spectroscopy to characterize the oxides formed on a number of different Fe‐Cr alloy thin films oxidized in air at 300 °C. Data was also obtained on pure iron and chromium thin films. The oxide thickness varied almost linearly with chromium concentration between 15 and 45 wt. %. Logarithmic growth kinetics persisted for chromium and iron‐chromium films whereas parabolic kinetics were found for the iron films. The chromium film kinetics were comparable to those of the Fe 20 wt. % alloy.

ISSN:0021-8979    

DOI:10.1063/1.328381

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The new wavelength‐division solar cell is proposed and its conversion efficiency is calculated. The proposed diode structure can be fabricated by the usual epitaxial growth technique. The considered materials are the combination of InP and In0.58Ga0.42As0.84P0.16having the band‐gap energy of 0.827 eV. The calculated maximum conversion efficiency is 19.5% at air‐mass‐zero (AM0) condition which can be improved by the growth of a CdS window layer on the InP surface. With thick CdS on InP, 22.2% efficiency is obtainable, and when the thickness of CdS is as thin as 0.2 &mgr;m, 27% efficiency will be attainable. Fabrication of the proposed structure with the GaAlAs/GaAs system gives a conversion efficiency of 23.5% which is about the same as conventional heteroface or graded‐band‐gap solar cells. The optimum layer thicknesses that give maximum efficiency are also determined in this paper.

ISSN:0021-8979    

DOI:10.1063/1.328382

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Resonant fluxon propagation on an overlap‐geometry Josephson tunnel junction of length 5&lgr;Jhaving a McCumber &bgr;c=5&pgr; is studied by numerical integration of the circuit equations of a 50‐section lumped RSJ‐type model. The zero‐field steps in the dc current‐voltage characteristic of the junction deriving from the two lowest order resonant fluxon configurations are calculated, and the switching mechanisms defining the upper and lower current thresholds are described. The power spectra of the radiation emitted from one end of the junction when it is current biased on each of these two zero‐field steps is calculated assuming negligible loading. An applied dc magnetic field is shown to cause a small increase in the frequency of this radiation, in contrast with reported experimental measurements.

ISSN:0021-8979    

DOI:10.1063/1.328383

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A generalized expression of current gain for nonuniformly doped bipolar transistor considering the effects of energy‐gap narrowing, doping‐dependent diffusivity, contact‐surface and bulk recombinations, is derived by using generalized current flow equations and continuity equations. Based on the derived expression, the generalized expressions of current gain and transit times across the neutral base and emitter regions in the case of uniformly doped transistor structure are calculated in detail. Numerical results have shown that the recombination in heavily doped emitter may not be neglected and the conventional charge control expression of current gain does give erroneous predictions. Moreover, the current gain and transit time for a transparent emitter bipolar transistor have been studied, which are shown to be quite sensitive to the contact‐surface recombination velocity, and are found to be useful in the study of microwave bipolar transistor.

ISSN:0021-8979    

DOI:10.1063/1.328384

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Contact‐limited, ambipolar transport, which describes the drift current behavior of minority carriers not confined to the active layer of double heterostructure injection lasers, is used to predict different behavior than previous calculations for the temperature dependence of the threshold current for lasing. The high‐temperature coefficients of some lasers may more easily be explained using the model.

ISSN:0021-8979    

DOI:10.1063/1.328385

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A novel image display system based upon the photoelectrophoretic phenomenon is studied. The display cell consists of a sandwich structure of an electrode‐photoconductor layer‐suspension (particles and suspending fluid)‐counter electrode. A visual image is produced by three steps: (1) application of external voltage, (2) exposure to an optical image while the voltage is applied, and (3) a short circuiting of the cell. An important feature of this system is that during this operation a charge exchange between particles and electrodes is not required in exposed areas. In addition, this system permits the employment of less photosensitive particles. The effects of the photoconductor layer thickness, light intensity, external voltage, and fluid component on optical characteristics are studied. The forces acting on particles during this operation are also discussed.

ISSN:0021-8979    

DOI:10.1063/1.328386

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The numerical solution of the near field patterns of both axial and circumferential slots on a circular conducting cylinder is obtained. Equiamplitude contours around the cylinder and radial variation of the field along the constant azimuthal coordinates are presented. The calculated results show that the pattern above the slot completely coincide with that of a similarly situated slot in an infinite ground plane.

ISSN:0021-8979    

DOI:10.1063/1.328387

出版商:AIP    

年代:1980

数据来源: AIP