摘要:

We have analyzed a phased‐array semiconductor laser coupled to an external cavity containing a spatial filter. The results indicate that the external cavity‐spatial filter combination couples the natural supermodes of the array. Thus if a single supermode were to be emitted by the antireflection‐coated facet, the reflected field would couple into many supermodes of the same parity. By self‐consistently modeling the laser‐cavity configuration we show that substantial mode mixing occurs in practical cases and its effect is more pronounced when the coupling coefficient is small.

ISSN:0003-6951    

DOI:10.1063/1.97164

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Following the recent observation in this laboratory of a charge induced damage effect in insulators under inert gas ion bombardment, the influence of the charge state of the beam (ion or atom) on the sputtering yield of insulating and semiconducting materials has been investigated. A series of sputter measurements has been carried out on Au, Ta2O5, Si, GaAs, and glass using calibrated ion and atom fluxes. For this purpose a recently developed gun capable of producing raster‐scanned, microfocused energetic ion or atom beams was employed. While for the conductor Au, as expected, no effect was seen, for the remaining materials sputter yield increases of up to 150% were observed under ion bombardment which implies the existence of a substantial electronic sputtering effect in insulators and semiconductors due to low‐energy ion bombardment.

ISSN:0003-6951    

DOI:10.1063/1.97165

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The effect of a compositionally graded buffer layer (CGBL) in AlGaAs laser diodes grown by molecular beam epitaxy is presented. The threshold current and the differential quantum efficiency are improved by a factor of ∼2. The lifetime is markedly improved by using a CGBL and it is comparable to that of lasers grown by liquid phase epitaxy.

ISSN:0003-6951    

DOI:10.1063/1.97166

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Significant improvements are reported in the energy conversion efficiency of low resistivity silicon solar cells when measured under concentrated sunlight. These improvements result primarily from increased short‐circuit current density due to the use of a microgrooved cell structure with obliquely transversing metallization fingers. Peak efficiencies are 23.6% at 100 suns concentration with values up to 22.7% maintained at 273 suns concentration.

ISSN:0003-6951    

DOI:10.1063/1.97167

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Electron irradiation of WF6films on Si has been studied using scanning Auger and electron microscopic techniques. In contrast to metal organics, electron stimulated decomposition of WF6is found to result in formation of pure W deposits; patterned films are formed by scanning the focused electron beam. The morphology of the films is particulate and the manner in which this originates is discussed.

ISSN:0003-6951    

DOI:10.1063/1.97168

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Deep levels introduced in boron‐doped silicon by heat‐pulse annealing with a tungsten‐halogen flashlamp are investigated using deep level transient spectroscopy. Two majority‐carrier trapping levels in the band gap, atEv+0.32 eV and atEv+0.45 eV, are observed. These results are compared to those obtained by furnace quenching and laser annealing studies. Both the position in the gap and the annealing kinetics of the hole trap atEv+0.45 eV suggest that this center is due to an interstitial iron impurity in the lattice. The deep levels are not consistently observed in all flashlamp‐annealed Si crystals utilized in the present work.

ISSN:0003-6951    

DOI:10.1063/1.97169

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Measurement of the minority‐carrier mobility in the base region of the high‐voltage metal‐insulator‐N‐P solar cell, as well as in other 0.1 &OHgr; cm cells, provides direct proof that the high voltages measured for that cell are due not only to improved emitter characteristics but to an improved base region as well. The base characteristics are shown to be quite sensitive to the effects of diffusion induced lattice stress originating in the emitter. The implications of these findings with regard to the fabrication of high efficiency cells are discussed.

ISSN:0003-6951    

DOI:10.1063/1.97170

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Ion beam etching (IBE) and reactive IBE (RIBE) of GaAs and AlxGa1−xAs(x=0.3–0.5) were examined using Ar and Ar/O2(O2: 2.0 and 5.3 mol %). In Ar IBE of 100 eV or more, neither GaAs nor AlGaAs was substantially oxidized and equirate etching was observed. In 50 eV Ar/O2(2–5.3%) RIBE, however, both GaAs and AlGaAs were oxidized and etched little. In 100 eV Ar/O2(2%) RIBE, especially, AlGaAs was oxidized but GaAs was not, and a maximum selectivity of 13 was obtained in the etching of GaAs/Al0.5Ga0.5As. Impinging O+ions were found to be the main origin of oxidation.

ISSN:0003-6951    

DOI:10.1063/1.97171

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We present new experimental results of ballistic electron transport through thinn+‐GaAs layers. Measurements were done on tunneling hot‐electron transfer amplifier devices composed of GaAs and AlGaAs layers. In devices with GaAs active regions (bases) of 300 and 800 A˚, collisionless or ballistic transport was observed. By performing hot‐electron energy spectroscopy we found that the collected ballistic distributions were similar in shape but differed in magnitude. This suggests the existence of a strong scattering mechanism which randomizes the otherwise ballistic electrons. The maximum differential current transfer ratio &agr; was 0.9 in devices for which about 75% of the injected current traversed the base ballistically. The presence of ballistic transport has also allowed the measurement of the AlGaAs barrier height through observation of the onset of current collection in the devices. Barrier heights higher than those recently reported have been measured. In addition we show the effects of grading the collector barrier. The most noted effect in these cases was a higher transfer ratio.

ISSN:0003-6951    

DOI:10.1063/1.97172

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We have performed open‐tube diffusion of Zn inton‐type InP over the temperature range 525–675 °C. For heavily doped InP, the observed diffusion profiles are consistent with an interstitial‐substitutional model where the interstitial Zn is doubly ionized. However, for undoped InP the profiles have a significantly different shape and the diffusion is deeper. Assumption of neutral interstitial Zn is able to account for these two changes. A tentative model is proposed to explain the dependence of the interstitial Zn ionization state on the starting substrate dopant concentration.

ISSN:0003-6951    

DOI:10.1063/1.97173

出版商:AIP    

年代:1986

数据来源: AIP