摘要:

Clean mode excitation and transmission have been observed in inverted‐ridge waveguides fabricated by liquid‐phase epitaxy of Ga0.7Al0.3As‐GaAs structures over preferentially etched channels.

ISSN:0003-6951    

DOI:10.1063/1.88614

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The short‐section critical current densityjcof neutron‐irradiated Nb3Sn composite wires has been measured at 4.2 K in transverse magnetic fields up to 10 T. Irradiation was conducted at ∼6 K, andjcmeasurements were made after annealing to 77 K. A fluence of 4.8×1017n/cm2(E≳0.1 MeV) increasedjc(H) (forH≳1.5 T) above high unirradiated values (about 1×106A/cm2at 4 T). The enhancement injcincreased with field, to 45% at 10 T. Samples irradiated to 1.1×1018n/cm2showed enhancements injca few percent less than samples given the lower dose. After annealing to 295 and 415 K, roughly half of thejcenhancement remained forH≳4 T. Changes in the defect structure caused by irradiation and subsequent annealing, and which are responsible for increased flux pinning, are discussed.

ISSN:0003-6951    

DOI:10.1063/1.88615

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Double heterojunction PbS‐PbS1−xSex‐PbS laser diodes have been fabricated by hot‐wall molecular beam epitaxy. The lasers had stripe geometry of 100‐&mgr;m width formed by MgF2passivation. Structures for electron and hole injection, respectively, are compared. Devices with 1‐&mgr;m‐thick active layers showed threshold current densities of about 400 A/cm2at 77 K and 1.4×104A/cm2at 190 K. cw operation could be realized up to 96 K.

ISSN:0003-6951    

DOI:10.1063/1.88616

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Thin film solar cells, ∼1 &mgr;m thick, have been fabricated from amorphous silicon deposited from a glow discharge in silane. The cells were made in ap‐i‐nstructure by using doping gases in the discharge. The best power conversion efficiency to date is 2.4% in AM‐1 sunlight. The maximum efficiency of thin‐film amorphous silicon solar cells is estimated to be ∼14–15%.

ISSN:0003-6951    

DOI:10.1063/1.88617

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The gate capacitance of a nearly pinched‐off semiconducting channel located between gate and substrate depletion layers is derived for the high‐frequency regime in which the substrate charge does not change with ac channel charge. The distance corresponding to the inverse gate capacitance exceeds the gate depletion layer width, and theR‐Ctime constant per unit channel length approaches the inverse of the product of channel carrier mobility and voltage equivalent of temperature. OrdinaryC‐Vanalysis at high frequency provides an artifactitious impurity profile which is fairly independent of the doping concentration and of the substrate and which varies in proportion to absolute temperature. Reconstruction of the true impurity profile from this artifactitious profile is discussed.

ISSN:0003-6951    

DOI:10.1063/1.88618

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A new class of infrared detectors is proposed and experimental results are presented for a prototype device. The material used is LaF3, an ionic conductor with a capacitance that varies exponentially with temperature. The detectivity of a prototype detector is estimated from measured signal voltages and incident power, and a Johnson noise voltage is calculated from the measured resistance. At a modulation frequency of 20 Hz the estimated detectivity is ∼2×106cm Hz1/2 W−1. For the parameters characterizing this device, the estimated detectivity is consistent with a theoretical prediction. The theory further predicts an optimum detectivity of ∼109cm Hz1/2 W−1for much thinner devices than the prototypes.

ISSN:0003-6951    

DOI:10.1063/1.88619

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Measurements of the standard deviation &sgr;sof the surface potential fluctuations in MOS structures were performed by the conductance technique of Nicollian and Goetzberger for different temperatures and surface potentials. The values of &sgr;swere compared with the three‐dimensional mathematical model suggested by Brews and the quasiuniform model of the surface potential fluctuations generated by interface charge inhomogeneities. Good agreement was obtained with the model of Brews. We conclude that the interface charges are not agglomerated in the form of charge islands but are more or less evenly distributed. For the lower limit of the minimum wavelength of the interface charge inhomogeneities, we obtain a value of 75 A˚. The upper limit of 100 A˚ as assumed by Brews seems to be reasonable. Negative interface charges are either absent or at most present at a low level.

ISSN:0003-6951    

DOI:10.1063/1.88620

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We report pulsed operation of an electrically pumped GaAs single heterostructure ring laser at 77 °K. Guided modes within the laser are totally internally reflected at cleaved facets and output beams are obtained by coupling from an integrated grating. Thresholds as low as 700 A/cm2have been obtained and highly polarized highly collimated beams (1°×7° divergence) with a total output power of 70 mW have been observed.

ISSN:0003-6951    

DOI:10.1063/1.88621

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The statistical distribution of lifetimes of routinely grown and fabricated continuously operated (Al,Ga)As double‐heterostructure lasers is presented and discussed. The 90 typical devices studied were operated as lasers in a dry‐nitrogen elevated‐temperature ambient (70 °C) until failure. The resulting median life, &tgr;m=750 h, and mean life, ⟨&tgr;⟩=1370 h, extrapolate to &tgr;m=5.7 years and ⟨&tgr;⟩=10.5 years at room temperature (22 °C) using a 0.7‐eV activation energy. The observed lifetimes are consistent with a model in which 17% of the lasers die prematurely as infant mortalities while 83% die by a mechanism well characterized by a lognormal distribution. The value of the standard deviation (&sgr;=1.1) in ln&tgr; is typical of other semiconductor devices.

ISSN:0003-6951    

DOI:10.1063/1.88622

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The barrier height of a Pd‐CdS Schottky diode is reported to decrease markedly when exposed to hydrogen. This effect is believed to be due to the decrease in Pd work function. It makes a good simple hydrogen detector (even at 298 °K) over the range 500–5000 ppm H2.

ISSN:0003-6951    

DOI:10.1063/1.88623

出版商:AIP    

年代:1976

数据来源: AIP