摘要:

The theory of self‐diffraction of light by transient free‐carrier gratings in semiconductors has been expanded to the case in which nonlinear absorption of light creates the grating. Its application to the experiments performed allowed determination of the free‐carrier ambipolar diffusion coefficients in CdS, CdSe, and ZnSe crystals, and the mechanism of free‐carrier recombination and carrier lifetime in CdS at low temperatures.

ISSN:0003-6951    

DOI:10.1063/1.90270

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A focused beam of electrons in coincidence with a high current density Ar+sputtering beam and SIMS detection has been used to perform accurate depth profiling analyses of sodium in SiO2films. Conditions for exact charge compensation are described, and analyses of a 150‐keV sodium implant in a 0.73‐&mgr;m film of SiO2are presented. Without charge neutralization, 98% of the implanted sodium moved to the SiO2/Si interface during SIMS analysis, whereas optimum charge compensation resulted in a basically unaltered implant profile with only 0.06% sodium at the interface.

ISSN:0003-6951    

DOI:10.1063/1.90271

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

An Al0.14Ga0.86As solar cell with an Al0.92Ga0.08As window has been operated in AM2 sunlight at flux concentrations up to 899 suns with a conversion efficiency at this maximum concentration of 15.5%. Evaluation of the cells shows minority‐carrier diffusion lengths ≳2 &mgr;m and quantum efficiencies ≈0.85. The use of such a cell for spectral‐splitting high‐efficiency solar cell applications is discussed.

ISSN:0003-6951    

DOI:10.1063/1.90272

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Various LPE GaAs/Ga1−XAlXAs layers and DH lasers of direct alloy composition (0⩽X≲0.35) have been excited by photoluminescence and current injection at 300 K, respectively. All samples emit a weak low-energy band (BIII), peaking at about 1.02 eV independent of material compositionXand doping. The responsible deep-level centers therefore remain fixed energetically at 1.02 eV, relative to the (more distant) band edge, as the gap is varied. This striking feature and other characteristics support the hypothesis that BIII results from radiative recombination at defects which are very similar, if not identical, to those labeledE3in literature on this

ISSN:0003-6951    

DOI:10.1063/1.90273

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

It is shown that the time‐dependent capacitance change associated trap refilling in a Schottky diode is nonexponential, consisting in the sum of two contributions which reduce to a single one for reverse biases smaller thanVSCO, the space‐charge crossover voltage. Determination ofVSCOyields both the trap depth &Dgr;Eand its capture cross section. This is experimentally demonstrated for the oxygen‐related trap inn‐GaAs. We find &Dgr;E=0.67 eV in good agreement with other determinations.

ISSN:0003-6951    

DOI:10.1063/1.90274

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We study a simple model of light emission from inelastic electron tunneling into small metallic particles, here represented as spheres. Within a quasistatic approximation for the induced polarization in the electrodes, we calculate the radiated intensity as a function of frequency and direction.

ISSN:0003-6951    

DOI:10.1063/1.90275

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Ion implantation was used to introduce 20 at.% Si into anA‐15 Nb3Al0.9Si0.1substrate. The surface was depleted of Al by a diffusion anneal. The Al deficiency was replaced with Si by successive implantations. The surface structures were determined from reflection electron diffraction photographs. After depletion and implantation, the sample surfaces had a disordered bcc structure. A subsequent 800 °C anneal transformed these surfaces intoA‐15 Nb3Al0.2Si0.8by epitaxial recrystallization.

ISSN:0003-6951    

DOI:10.1063/1.90276

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The oxidation state of iridium ions in an oxide film grown electrochemically on an Ir metal reflector electrode in aqueous 0.5MH2SO4electrolyte can be rapidly and reversibly modulated by voltage pulses of 1 V amplitude according to the reaction: Ir(OH)n(transparent) &rlarr2;IrOx(OH)n−x(colored)+xH++xe. This valency interconversion produces a marked change in light absorption throughout the visible wavelength region and occurs without change in film thickness. Color‐bleach cycles exhibit reflectance contrast changes, &Dgr;R/R, and charging times, &tgr;, suitable for electrochromic display devices, e.g., for a film 700 A˚ thick: &Dgr;R/R=60% at &lgr;=546 nm and &tgr;≈40 msec. The fast write‐erase times are made possible by the highly porous and hydrated nature of the oxide film. The charge (∼20 mC cm−2) and energy (∼20 mJ cm−2) are comparable with those for other electrochromic oxide systems, e.g., the tungsten bronzes. Advantages of the iridium oxide system include: (i) fast response; (ii) stability of the colored written state in the presence of water and dissolved O2; (iii) broad spectral absorption; and (iv) the ability to grow and reform the oxide layerinsituin the electro‐optic display cell. Electrochromic spectra of anodic iridium oxide films are illustrated and related to charge‐transfer and intervalency transitions.

ISSN:0003-6951    

DOI:10.1063/1.90277

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Mercuric iodide detectors, operating at room temperature with the FET of the first stage of amplification cooled with a two‐stage Peltier element, have been used to detect low‐energy x rays from light elements excited by 2.0‐ and 6.1‐MeV &agr; particles. X‐ray lines from Na (1.04 keV) and Mg (1.25 keV) have been seen for the first time with room‐temperature energy‐dispersive detectors. A resolution of 390 eV at 1.25 keV was obtained. Further improvement of the resolution is believed to be achievable. However, even the present characteristics are adequate for many applications in x‐ray fluorescence and elemental analysis. Several such possible applications are suggested.

ISSN:0003-6951    

DOI:10.1063/1.90278

出版商:AIP    

年代:1978

数据来源: AIP