摘要:

Recent measurements of less‐than‐full shot noise in GaAs/AlGaAs quantum‐well infrared detectors can be explained in terms of standard photoconductor generation‐recombination theory. Therefore, more complex models are not yet necessary.

ISSN:0021-8979    

DOI:10.1063/1.348426

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The expression for the ratio between the noise current and full shot noise contained in our recent paper [J. Appl. Phys.67, 7608 (1990)] is based entirely on standard generation‐recombination noise theory, and does not represent a more complex model as Beck suggests [J. Appl. Phys.69, xxx (1991)]. The equations presented by Beck contain errors, but once these errors are corrected, his equations and ours yield the same quantitative predictions.

ISSN:0021-8979    

DOI:10.1063/1.348427

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We investigated the current‐voltage characteristics of double‐barrier resonant tunneling diodes with areas ranged from ∼400 &mgr;m2to ∼10 &mgr;m2at a temperature of 300 and 4.2 K. For diodes of large areas, the characteristic negative differential resistance is always accompanied by a hysteresis and oscillation at several tens of MHz. However, for smaller diodes, the hysteresis and oscillation disappear, and the tunneling current shows a smooth transition between peak and valley. Our observation shows that the hysteresis can result from a load line effect. Were the hysteresis an intrinsic behavior, it should persist as the device area is reduced. We therefore conclude that the intrinsic bistability is yet to be experimentally confirmed.

ISSN:0021-8979    

DOI:10.1063/1.348428

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Solar cells with less than 1% front‐surface metal shading loss have been made with a deep‐grooving hollow cathode dry etching process. Compared with standard laser‐grooved cells, a 4% relative increase in short‐circuit current density has been demonstrated. Open‐circuit voltages of over 640 mV (air mass 1.5, 25 °C), a fill factor of almost 79%, and the application of an antireflection coating have resulted in a one‐sun efficiency of 19.2%. This is one of the highest efficiencies yet reported for a cleaved 4 cm2silicon solar cell.

ISSN:0021-8979    

DOI:10.1063/1.348429

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We consider the proximity effect between high‐temperature superconducting cuprates and ordinary metals in the context of superconductor‐normal‐superconductor (S‐N‐S) microbridges. The theory of the proximity effect for conventional superconductors predicts that superconductivity can only be weakly induced by the coupling of the cuprates with metals such as gold or silver. Experimental investigations of this system have yielded results consistent with this prediction. We discuss the possibility of fabricating S‐N‐S microbridges with desirable properties by using more appropriate normal layers in the devices.

ISSN:0021-8979    

DOI:10.1063/1.348430

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Point defect concentrations in InGaAsP grown from liquid phases were calculated. Vacancies and antisites were taken to be dominant defects. The calculated antisite concentrations decrease with increasing band gap, while the vacancy concentrations are weakly dependent on composition. Although development of dislocations is known to be easier in InGaAsP lattice matched to GaAs than in those lattice matched to InP, the difference in the vacancy concentration between them is small when their growth temperatures are assumed to be the same. However, a high growth temperature usually adopted for InGaAsP on GaAs will result in larger vacancy concentrations.

ISSN:0021-8979    

DOI:10.1063/1.348431

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The experimental magnetic‐field derivative of the microwave absorption signal, obtained using electron paramagnetic resonance techniques, has a line shape that depends on the Ginzburg–Landau model parameter &kgr; of the superconducting sample at a given temperature. The type‐II superconducting equation of state can be utilized to describe the drop in the output microwave power derivative, from its maximum atH&bartil;Hc1to its much lower values whenH≫Hc1, in order to estimate the values of &kgr;. The technique also allows for the experimental determination of hysteretic behavior inBas a function ofH.

ISSN:0021-8979    

DOI:10.1063/1.348432

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A Nb‐InAs‐Nb superconductor‐semiconductor‐superconductor weak link based on a high‐mobility homoepitaxialn‐InAs film was reported recently [Akazaki, Kawakami, and Nittu J. Appl. Phys.66, 6121 (1989)]. Measurements of the electron concentration, effective mass, and mobility allowed the coherence length in the normal link to be calculated. The mobility was high enough that the dirty limit was not applicable in the temperature range (∼2–7  K) over which the device critical current was measured. The temperature dependence of the critical current could not be fit by the usual theoretical form, even though an expression for the coherence length was used that should be applicable in both the clean and dirty limits. In this paper is demonstrated an excellent fit to the data, obtained by using the magnitude of the coherence length as a fitting parameter and assuming the dirty limit temperature dependence. This implies a coherence length proportional toT−1/2but far shorter than that calculated from the known material parameters. It is suggested that a different scaling length may apply in high‐mobility devices.

ISSN:0021-8979    

DOI:10.1063/1.348433

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Small‐signal ac admittance data are presented, and shown to provide accurate and unambiguous evidence ofp‐type behavior in Li‐doped ZnSe epilayers grown onp+‐GaAs. The devices measured are two‐terminal vertical‐transport structures, with unequal‐area contacts in order to distinguish effects arising from the top metal Schottky barrier from those arising from the heterojunction. Qualitative features of the data alone are sufficient to determine the (positive) sign of the mobile carriers in the ZnSe. The data are analyzed using an equivalent‐circuit model shown to be reliable forn‐type ZnSe, from which the net doping and the ZnSe resistivity are extracted. Using these quantities, the ZnSe hole mobility is found to be about 28±4 cm2/V s. Schottky barrier and heterojunction barrier heights are also determined.

ISSN:0021-8979    

DOI:10.1063/1.348434

出版商:AIP    

年代:1991

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.348978

出版商:AIP    

年代:1991

数据来源: AIP