摘要:

A semilogarithmic expression that accurately approximates gain‐current curves of quantum‐well lasers and is useful for optimization of device performance is derived. The derivation uses both a curve fitting of the calculated curves and approximate analytical evaluation of integrals that comprise the gain model. The derived expression is used to explain the observed increase in the threshold current of single‐ and multiple‐quantum‐well lasers.

ISSN:0021-8979    

DOI:10.1063/1.342028

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Thin amorphous GaAs layers on (100)‐oriented substrates, generated by Si+ion bombardment at 77 K, have been observed to recrystallize epitaxially during 1.5‐MeV Ne+bombardment in the temperature range 75–135 °C. Crystallization proceeds linearly with increasing ion fluence, except in the near‐surface region, and the process is characterized by an activation energy of 0.16 eV, which is an order of magnitude smaller than that obtained for conventional thermal annealing at much higher temperatures.

ISSN:0021-8979    

DOI:10.1063/1.342029

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Metal‐nitride‐oxide‐silicon structures with various nitride thicknesses deposited on a 50–nm silicon dioxide layer prepared by a thermochemical reaction of tetraethylorthosilicate (TEOS) have been prepared. Capacitance‐voltage (C‐V) measurements have been performed after applying a voltage for a fixed time to determine the amount of accumulated interface charge. Infrared measurements have been carried out to obtain qualitative information about the internal stress in the TEOS layer. The accumulated charge and internal stress in TEOS increases with increasing nitride thickness. This observation indicates a lowering of the energy gap of TEOS.

ISSN:0021-8979    

DOI:10.1063/1.342030

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Use of models without doping effects on the interstitial‐substitutional interchange can lead to the identification of an apparently larger charge state of the interstitial and will increase the apparent activation energy of diffusion. This increase is approximately equivalent to the zinc‐solubility activation energy for substrate doping near the substitutional‐zinc concentration at the surface.

ISSN:0021-8979    

DOI:10.1063/1.342031

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Schottky barrier heights are measured by current‐voltage and capacitance‐voltage methods for Al/n‐GaAs contacts with a rare‐earth metal (Sm, Dy, Yb) interlayer, which forms a stable alloy with Al but does not form an electrically active site in GaAs. The Schottky barrier height for each contact is found to be lowered with diode factorn<1.06, compared to ideal Al/n‐GaAs and rare‐earth metal/n‐GaAs contacts. The mechanisms for the lowering are discussed from standpoints of alloy formation and diffusion across the interface.

ISSN:0021-8979    

DOI:10.1063/1.342032

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

We report a study of threshold characteristics of as‐grown surface‐emitting lasers fabricated with molecular‐beam epitaxy by the monolithic integration of two quarter‐wave high reflectors (mirrors) of AlAs/Al0.4Ga0.6As surrounding an active spacer layer. The spacer was either a multiple quantum well of GaAs/Al0.4Ga0.6As (100 A˚/200 A˚) or GaAs. Several structures were grown corresponding to different mirror reflectance and different spacer thicknesses from ultrashort 0.9 to 10 &mgr;m. One of the structures was chemically etched to form a two‐dimensional array of microlasers. All of the structures were photopumped at room temperature, and the lasing threshold was determined. Without any lateral confinement, the threshold irradiance was as low as 2×105W/cm2. Near‐field images of the light emitted slightly above threshold reveal several competing filaments. This competition broadens the lasing linewidth, but can be controlled by lateral confinement schemes.

ISSN:0021-8979    

DOI:10.1063/1.342033

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

We report on an improved method of displaying the interface state density versus energy plots that is particularly useful for observing subtle changes in curve shape caused by the presence of states at a particular energy level. Essentially, the derivative of the density of interface states with respect to energy is plotted versus energy. An example which is presented using this technique is the monitoring of the effectiveness of cleaning and annealing treatments on Ar ion‐beam‐bombarded silicon. Subtle changes in the interface state distribution can be observed.

ISSN:0021-8979    

DOI:10.1063/1.342034

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

In this paper we find the microscopic mechanism of persistent photoconductivity in doping‐modulated amorphous silicon superlattices is the same as that of compensated amorphous silicon. The carrier separation due to a built‐inn‐pjunction field can explain persistent photoconductivity in compensated amorphous silicon films. This new analysis is favored by experimental results on the persistent photoconductivity in compensated as well as in layered amorphous silicon films.

ISSN:0021-8979    

DOI:10.1063/1.342035

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Analysis of modulational instability in optical fibers based on a phase‐matched four‐photon mixing approach is extended by taking into account higher‐order dispersion. Fourth‐order dispersion governs the modulation frequency in a region near zero‐dispersion wavelength, resulting in frequency saturation. The frequency decreases as group delay dispersion becomes dominant in comparison to the fourth‐order dispersion. To deepen the modulation, a phase‐matching condition for four‐photon mixing must be satisfied. A technique is studied which uses externally controllable birefringence of optical fibers to achieve phase‐matching at a given modulation frequency.

ISSN:0021-8979    

DOI:10.1063/1.342036

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Porous Vycor glass has been impregnated with selenium and tellurium by pressure forcing the nonwetting semiconductor melt into the interconnected pores. Dense semiconductor microstructures with a characteristic size of 50 A˚ can be fabricated by this technique. Measurements are reported which show the composite is suitable for both optical and electrical transport studies, particularly those addressing possible quantum confinement of carriers in this class of materials.

ISSN:0021-8979    

DOI:10.1063/1.342037

出版商:AIP    

年代:1988

数据来源: AIP