摘要:

The current‐voltage characteristics of Si:In double‐injection devices were measured up to breakdown in the temperature range 20–80 K. To vary the amount of optical carrier generation the devices were either exposed to a 50 K cold shield or a 300 K background. The breakdown voltages were found to be strongly dependent on device temperature and irradiation intensity. By using simple analytical expressions it is shown that the unexpected low values at high temperatures or at high irradiation levels are due to large densities of thermally or optically generated holes. To obtain a satisfactory agreement between theory and experiment the regional approximation method is employed. The analysis extends previous treatments by taking into account field‐dependent mobilities and capture coefficients. The description of the prebreakdown characteristics includes also the lowering of the ionization energies of the acceptor centers at high field strengths.

ISSN:0021-8979    

DOI:10.1063/1.335667

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new type of plasma source is presented: A collisionless plasma is formed by producing ions on one end and electrons on the other of a cylindrical vacuum chamber in a solenoidal magnetic field. The ions are produced by contact ionization of potassium on tungsten. The source of electrons is a LaB6plate. In the usual single‐endedQmachine the elements rhenium, iridium, and platinum are tested as ionizing metals for potassium and barium.

ISSN:0021-8979    

DOI:10.1063/1.335669

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This paper reports a new method for evaluating laser diodes by measuring the variation in driving current of a laser diode operated at a constant light output power against ambient temperature. A close relation was found between the temperature at which the driving current runs away at a given value of light output and degradation in the active region. Selection based on critical temperature is applicable to a simple and effective screening method for long‐living laser diodes.

ISSN:0021-8979    

DOI:10.1063/1.335617

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We present an improved version of a heat‐conduction model which leads to better‐computed values of the anodic voltage drops for electric discharges in a liquid dielectric, with a short interelectrode gap (about 50 &mgr;m) and short duration (10–1000 &mgr;s). The results obtained show monotonic variations according to the duration of the discharge and peak current, and correspond to the measured value of the total interelectrode voltage drop.

ISSN:0021-8979    

DOI:10.1063/1.335618

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A general type of the boundary condition given by Simmons and Taylor is used to derive the expression for the nonequilibrium capacitance of the Schottky diode. It is shown that the deviation of the capacitance from its quasi‐equilibrium value is larger than has been previously reported. Except for the extremely strong forward biases the quasi‐equilibrium capacitance remains a valid approximation.

ISSN:0021-8979    

DOI:10.1063/1.335619

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Low‐pressure metalorganic vapor‐phase epitaxy was adopted to grow AlGaAs epitaxial films by using triethyl‐gallium, trimethyl‐aluminum, and AsH3as the Ga, Al, and As sources, respectively. Growth rate, incorporation rates, and AlAs solid composition versus growth temperature have been investigated by electron probe microanalysis with the following results: the growth rate, the AlAs fraction in AlGaAs, and the Al and Ga incorporation rates increase with increasing growth temperature under reduced pressure. The Al incorporation rate increases more quickly than that of the Ga in AlGaAs. The above results are consistent with one another.

ISSN:0021-8979    

DOI:10.1063/1.335620

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Using theoretical calculations to generate Lyman &bgr; and &dgr; Stark‐broadened line profiles, we have found a simple parameterization of the line intensity full width at half maximum over a broad range of the atomic species [Z∈(6,18)], electron density [NE∈(1019,1025) cm−3], and electron temperature (TE=250,500,1000 eV). The parameters of the fits are presented together with a discussion of the method.

ISSN:0021-8979    

DOI:10.1063/1.335621

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Noncontact photoacoustic measurements were performed on GaAs samples with Michelson interferometry. The detection sensitivity of the vibration amplitude up to 0.01 A˚ was achieved. It is demonstrated that the sensitivity is increased drastically by the resonance of the sample itself. The sensitivity for the temperature rise is estimated to be on the order of 2×10−5 °C.

ISSN:0021-8979    

DOI:10.1063/1.335622

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Thin films of A15 Nb3Al have been prepared by reactive diffusion of sputter‐deposited Nb/Al multilayers. The diffusion reactions were studied byinsituannealing x‐ray diffraction in the temperature range 50–950 °C. Initially the Nb and Al sublayers react to form the phase NbAl3. This interface reaction prevents the formation of the &sgr;‐phase Nb2Al, frequently found as a second phase in A15 Nb3Al materials; NbAl3reacts with the remaining Nb to form the A15 phase. The highestTc, 16.2 K measured resistively and 15.2 K inductively, was found in a Nb/Al multilayer with an A15 cell parameter a0=5.195 A˚ which corresponds to ∼20 at. % Al. From a comparison with previous investigations of theTcdependence on Al concentration and A15 cell parameter, it is concluded that a small amount of the A15 phase has a higher composition of 22–23 at. % Al.

ISSN:0021-8979    

DOI:10.1063/1.335623

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The effect of UV preionization on the optical gas breakdown induced by a CO2laser pulse is studied experimentally. In the present work a UV spark plug and a pulsed CO2laser are used as the UV and IR sources, respectively. The experiments are carried out for helium and some other common gases in the pressure range of 10–1000 Torr to determine the breakdown probability. For all of the gases under study the probability appears higher when the gas is UV preionized. These results show the importance of the seed electrons for the IR‐induced gas breakdown supporting the theory that the cascade ionization process is dominating in the IR region requiring seed electrons to initiate the process. Oscilloscopic waveforms of the optical breakdown spark fluorescence are also observed which shows the optical breakdown occurs more rapidly when the gas is UV preionized.

ISSN:0021-8979    

DOI:10.1063/1.335624

出版商:AIP    

年代:1985

数据来源: AIP