摘要:

The performance and appearance of an electrophoretic display is strongly dependent on the stability of the colloidal suspension in the device. Two primary degradation modes in a suspension have been identified. One is classified as pigment agglomeration which is caused by an insufficient repulsive barrier between particles; the other is classified as pigment clustering which is caused by fluid motion within the cell. Both forms of instabilities are detrimental to the life of the display. The concept of colloid stability will be reviewed briefly and its relation to the image device will be discussed. The mechanism by which the suspension instabilities develop and the methods by which they can be eliminated will be described. Properly stabilized suspensions in a device have survived in excess of 2.5×108switches (15 600 h) with no serious signs of degradation.

ISSN:0021-8979    

DOI:10.1063/1.325511

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The electrical resistance of manganin was measured under pressures up to 220 kbar at room temperature. The pressure was produced by means of a multianvil apparatus using semisintered magnesia for the pressure medium and was calibrated against well‐known fixed points. Obtained results show a linear relationship between the resistance and pressure up to 180 kbar with good reproducibility. The pressure coefficient of resistance turns out to be (2.322±0.008) ×10−3kbar−1, which is in close agreement with the value obtained under hydrostatic conditions. Manganin can be satisfactorily used as a pressure gauge for a high‐pressure experiment using a solid pressure medium. The deviation from the linearity observed above 180 kbar is ascribed to either an intrinsic property of Manganin or the uncertainty of the fixed point adopted. If the linearity is assumed above 180 kbar, the transition pressure of GaP is estimated to be 206±2 kbar.

ISSN:0021-8979    

DOI:10.1063/1.325512

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Photodiodes of indium tin oxide deposited on single‐crystalp‐silicon are analyzed with respect to their electronic properties. Dark measurements include the current and capacitance dependences on voltage and temperature. Photocurrent measurements reveal the relationship to the illumination intensity, temperature, and wavelength of light. Analysis reveals a relatively large, but temperature‐dependent, built‐in voltage and a small interface recombination probability.

ISSN:0021-8979    

DOI:10.1063/1.325513

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Theoretical calculations show that for maximum output power of LED’s an optimal ratio between thep‐njunction depths and the diffusion lengths of minority carriers of 2–3 is required. A method based on the photoluminescence technique is described which allows the determination of thea/Lratio. Measurements on various types of luminescence diodes were carried out. In double‐heterostructure lasers diffusion lengths in the range 1.2–4.6 &mgr;m were estimated.

ISSN:0021-8979    

DOI:10.1063/1.325514

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The resistance change experienced in a Permalloy stripe when magnetized by an expanded bubble domain is considered from a theoretical standpoint. A model is developed after consideration of demagnetizing field strengths and thermal and electrical constraints. From this model the output signal level to be expected for any given expansion of the domain may be computed and used as a design aid.

ISSN:0021-8979    

DOI:10.1063/1.325515

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The electrical conduction in polyethylene induced by the irradiation of the short pulsed electron beam (100‐nsec time width) consists of the fast and the slow components. The former is attributed to the carrier transport in the crystalline part and the latter to that in the amorphous part. A logarithmic plot (Scher‐Montroll plot) of the slow part of the induced current versus time gives a knee at timeTr, which is thought to be the transit time of the carrier front between electrodes. Simple calculation by the formula &mgr;=L/TrEgives the apparent slow carrier mobility &mgr; of 5.6×10−7and 3.2×10−7cm2/V sec for the electron and the hole, respectively, at 343 K under a fieldEof 1.2 MV/cm for sample thicknessLof 12 &mgr;m. These apparent slow carrier mobilities are dependent on both the thickness and the field strength. These behaviors are discussed in terms of Scher‐Montroll theory on transport in amorphous substances. The activation energy of the mobility is in good agreement with the apparent trap depth obtained from the TSC measurement.

ISSN:0021-8979    

DOI:10.1063/1.325516

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The incorporation of Sn atoms as donor impurities in autoepitaxial GaAs films grown from beams of Ga and As4by the process of molecular beam epitaxy (MBE) has been studied in several ways. The sticking coefficient of Sn, as measured directly by modulated beam techniques, is unity over a wide range of growth conditions, and the Sn diffusion rate is low up to the maximum growth temperatures used (820 K). In thick (?1 &mgr;m) films, away from the substrate‐film interface, free‐donor profiles are flat, with a free‐carrier concentration proportional to the Sn flux. Electron mobilities at 300 and 77 K as a function of free‐donor concentration are close to theoretical, assuming a fairly low level of compensation, although there is no evidence for Sn atoms being incorporated as acceptors. There is, however, a surface rate limitation to the incorporation of Sn atoms, so that until a steady‐state surface population of Sn is formed, which can be as large as 0.1 monolayers, the free‐donor density is not constant, but increases exponentially to a steady‐state value. The rate constant associated with this process is strongly dependent on the As4flux, and to a lesser extent on substrate temperature. At constant growth rate (Ga flux constant) and constant Sn flux, therefore, transients are observed in the free‐donor concentration at the beginning of growth, or where the As4flux or substrate temperature are changed during growth. A simple chemical model is shown to describe this behavior.

ISSN:0021-8979    

DOI:10.1063/1.325517

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Niobium films have been prepared by bias sputtering in a conventional sputter system operated in the triode configuration. Gas analysis of the discharge and of the deposited films as well as resistivity and lattice‐parameter measurements provide the basis for the interpretation of the deposition process under ion bombardment. The importance of defining the relative rate of arrival of energetic ion versus neutrals in addition to defining the energy of arriving particles is emphasized. The close relationship of bias sputtering to ion implantation is stressed. A model for bias sputtering is developed which is suited for fine‐tuning film composition and structure and thereby the resultant thin‐film properties.

ISSN:0021-8979    

DOI:10.1063/1.325518

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Equations are derived that describe the effect of space charge on current injection into insulators under the approximations that, in the absence of space charge, lead to either the Fowler‐Nordheim equation or the Schottky equation. The effect of the space charge is that the field in the insulator at the electrode interface is different from the field with no space charge, and that the triangular shape of the potential barrier is distorted. If only the alteration of the cathode field is taken into account, as is often the case, the effect of the space charge is overestimated. Explicit solutions are found for the case of constant space charge, where the effect of the shape distortion can be described in terms of a single parameter, which is different for the two injection mechanisms considered—zero temperature tunneling and thermionic emission over the potential barrier. For either mechanism, however, the parameter is a measure of the ratio of the charge on the electrode to the charge contained within a characteristic distance—the charge‐free tunneling distance for tunneling injection or the position of the charge‐free potential maximum for thermionic injection.

ISSN:0021-8979    

DOI:10.1063/1.325519

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The high‐frequency behavior of niobium cat‐whisker point contacts has been studied using radiation from an optically pumped far‐infrared laser. When the point contacts are classified on the basis of their high‐frequency performance, their dcI‐Vcurves fall into recognizable groups. We find that the ac Josephson effect has a strong correlation with the gap‐related structure on theI‐Vcurve, but none at all with the apparent excess current observed in all the contacts. For high‐performance junctions, these and other features of theI‐Vcurves are very reproducible from contact to contact, allowing a comparison with the available theories. The experimental evidence seems to suggest that our point contacts are best modeled as extremely small metallic constrictions.

ISSN:0021-8979    

DOI:10.1063/1.325520

出版商:AIP    

年代:1978

数据来源: AIP