摘要:

We report the first cw, room‐temperature multiple quantum well transverse junction stripe laser (MQW TJS) with an alloy disordered heterobarrier. The addition of a lateral heterobarrier by zinc diffusion enhanced alloy disordering reduces the laser threshold by a factor of 3 compared to standard transverse junction stripe lasers processed simultaneously. The reduction in threshold and excellent single mode performance of the MQW TJS are attributed to the superior carrier and optical confinement of a single heterojunction compared to a homojunction. We demonstrate for the first time lateral injection in a multiple quantum well where the diffused junction plays an active (not passive) role in the injection process and that the transition region between complete disorder and no disorder forms the active region of the laser.

ISSN:0003-6951    

DOI:10.1063/1.97509

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The instability in the evolution of a nonlinear wave along a directional coupler is investigated with the beam propagation method, both for self‐focusing and for self‐defocusing materials. A new device is proposed for switching an intense light beam at the device output by changing the relative phase of a weak input signal.

ISSN:0003-6951    

DOI:10.1063/1.97510

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The mechanism by which NF3fueled XeF laser mixtures degrade has been identified. The degradation is due to the formation of trace amounts of N2which charge exchange with electron beam excited Ne+2to form N+2X2&Sgr;+g(v‘=3,4). The N+2X2&Sgr;+g(v‘=3,4) absorbs selectively at the 353‐nm band but not at the 351‐nm band. This has been confirmed experimentally by direct observation of the laser output spectrum which shows a significant decrease of the 353‐nm laser band with almost no decrease of the 351‐nm bands when N2is added to the laser mixture. A Stern–Volmer analysis of the decreased XeF* emission due to the addition of N2to the laser mixture has been performed and the charge exchange rate between N2and Ne+2of 9×10−10cm3/s deduced. The decrease of XeF laser output with N2addition has been measured for both F2and NF3fuels. The results are in good agreement with model calculations using measured and literature values for the reactions.

ISSN:0003-6951    

DOI:10.1063/1.97511

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

UV light pulses of nanosecond and picosecond duration were used to switch bistable nonlinear interference filters from their low to their high transmission level. At room temperature, switching times in the nanosecond range are measured. They are, to the authors’ knowledge, the shortest reported for such devices.

ISSN:0003-6951    

DOI:10.1063/1.97512

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

B2O3decomposition by reaction with Si has been studiedinsituby Auger electron spectroscopy in a Si molecular beam epitaxy environment as a function of the silicon flux (0<JSi<14.5 A˚/min) and the growth temperature (25 °C<Ts<800 °C). Quantitative analysis of Auger signals indicates that oxygen is associated with both SiO2and B2O3. Below a critical substrate temperature (Ts<500 °C), no reaction occurs between B2O3and Si. When the substrate temperature is higher than 500 °C, the atomic fraction of Si and B increases while that for SiO2and B2O3decreases. The chemical reaction which causes the signal changes is thermally activated, as shown by the dependence of the oxygen on boron concentration ratio,I[O/B], which drops rapidly according to an Arrhenius relation with an activation energyEa=4.5±1.0 eV. From the experimental results, we propose a model which involves B2O3reduction by Si to form the (Si‐B) and SiO2phases. SiO2is then decomposed by Si bombardment on the surface to produce SiO which subsequently desorbs.

ISSN:0003-6951    

DOI:10.1063/1.97513

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The compositional profile of the interface between plasma‐deposited amorphous silicon (a‐Si@B:H) and silicon nitride (a‐SiNx:H) thin films has been examined using high depth resolution Rutherford backscattering spectrometry. We have optimized the grazing exit angle geometry of the measurement using a model calculation which predicts a ∼20 A˚ interface depth resolution. The fundamental noise sources considered in the calculation are the energy straggling and angular divergence of ions traversing the target, detector noise, and geometrical effects. Experimentally, the major compositional change for both Si and N is found to take place within the interface depth resolution which is 18 A˚. However, we find a tail of ∼3 at. % nitrogen extending through a 50‐A˚a‐Si:H layer deposited on top ofa‐SiNx:H. Such a tail is not expected for the reverse order of layer deposition. The compositional asymmetry depending on the order of deposition is presumably associated with the reported asymmetry in the charge density at interfaces. The nitrogen contamination further implies that mosta‐Si:H/a‐SiNx:H quantum well structures are in fact based on nitrogen alloyeda‐Si:H layers.

ISSN:0003-6951    

DOI:10.1063/1.97514

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Clusters of Au and Ag deposited on the surface of highly oriented pyrolitic graphite have been imaged in air using a scanning tunneling microscope. An image is shown of a 350‐A˚ silver cluster obtained in the constant‐current (topographic) mode. In the variable‐current mode, clusters of 6–20 atoms have been observed with atomic resolution. The motion and growth of clusters on the support are observed.

ISSN:0003-6951    

DOI:10.1063/1.97515

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A method has been developed to measure the time‐resolved, stress‐induced wavelength shift of ruby luminescence under shock loading. Results of experiments at 40 and 99 kbar stresses are presented and compared with high pressure hydrostatic data. A brief discussion of the necessary improvements to obtain high resolution shock data to permit quantitative analysis is presented.

ISSN:0003-6951    

DOI:10.1063/1.97516

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Preparation and performance of separate avalanche and multiplication superlattice photodiodes are reported. The absorbing region of these devices consists of up to 100 InGaAs quantum wells separated by InP barriers grown by gas source molecular beam epitaxy. The well size varies from 50 to 20 A˚ with very well‐resolved exciton structures visible at room temperature. With thep‐njunction displaced into the InP layer, leakage currents as low as 0.1 nA are obtained at unity gain bias of 20 V. dc avalanche gain of up to 280 and rf gain of 20 are observed at a bias of 38 V.

ISSN:0003-6951    

DOI:10.1063/1.97517

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Electrical measurements during the thermal recovery of fast neutron irradiated GaAs confirm the main steps around 400 and 600 °C, corresponding to the decay of electron paramagnetic resonance identifiedV2−Gaand As4+Gacenters.

ISSN:0003-6951    

DOI:10.1063/1.97518

出版商:AIP    

年代:1986

数据来源: AIP