摘要:

The temperature and compositional dependences of the energy gap are determined for the alloy semiconductor mercury‐cadmium telluride (Hg1−xCdxTe). The cutoff wavelength was measured on photoconductive and photovoltaic infrared detectors where 0.17<x<0.60 over a temperature range 20<T< 300°K. Spectral response curves are shown to indicate the precision of the method. The temperature and compositional dependences of the energy gap are shown and the empirical expressionEg(eV) =1.59x−0.25+5.233(10−4)T(1−2.08x)+0.327x3is deduced.

ISSN:0021-8979    

DOI:10.1063/1.1657304

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A technique is described for microwave diagnostics of a transient plasma that makes use of an active Fabry‐Perot resonator, in which a positive‐feedback loop is to provide gain. The experimental results indicate that the technique is attractive from the point of view of sensitivity, dynamic range, time resolution and convenience of readout.

ISSN:0021-8979    

DOI:10.1063/1.1657305

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Microwave nonlinear effects have been observed in the plasma sheath surrounding a probe. Results were obtained for a PIG discharge operating at 2.0×10−2Torr xenon. The nonlinear effects include mixing, harmonic generation, and current rectification. The probe is connected directly to a 50‐&OHgr; coaxial transmission line through which the microwave signal is coupled to the sheath. Strong nonlinear interaction is observed when the probe is dc biased at a point in the exponential region of the Langmuir curve. The explanation of this interaction is based on the usual interpretation of the sheath as a nonlinear capacitance.

ISSN:0021-8979    

DOI:10.1063/1.1657306

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We describe a very simple technique for obtaining an instantaneous display of the electron energy distribution in a plasma. We electronically doubly differentiate the current‐voltage characteristic of the Langmuir probe, following the method of Druyvesteyn. In our technique, we use operational amplifiers for differentiation. Our new contributions are: First, we have discovered where the noise is produced that formerly made operational amplifiers unsatisfactory; second, we have demonstrated that this noise can be eliminated; and third, we have produced simple techniques for cross checking our double‐differentiating system to demonstrate that the noise‐elimination process does not appreciably distort the desired information.

ISSN:0021-8979    

DOI:10.1063/1.1657307

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The application of 1500‐J self‐focused 1.5‐MeV electron pulses of 25‐nsec duration to production of energetic plasmas has been studied by time resolved emission spectroscopy. In Ar and He at pressures of from 0.15 to 1.5 Torr a high‐energy plasma is formed which continues radiating for up to 500 &mgr;sec. Under drifting electron beam conditions the He plasma appears to be doubly ionized. Measurements of excitation temperature from the relative intensities of neutral He lines fit an equilibrium model 2 &mgr;sec after the electron passage and indicate a temperature of 10 000°K falling to 5000°K by 400 &mgr;sec. A measurement of the width of the He(I)4921‐Å line indicates an electron density of 1.2×1015cm−3at 70 &mgr;sec, falling to 3.4×1014cm−3by 200 &mgr;sec. Studies of an Ar plasma have shown the emission at peak excitation to be in the Ar(IV) spectrum. When the beam exceeds its critical current and is stopped by its own magnetic compression, in Ar, the quenching of the Ar(IV) emission indicates that the plasma reaches an energy which is high compared to the 145 eV necessary to four times ionize and remains above this level for 8 &mgr;sec.

ISSN:0021-8979    

DOI:10.1063/1.1657308

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A model is proposed to explain radiation damage and charge trapping in the oxide layer of MOS devices after exposure to ionizing radiation. This model is based upon the close similarity between radiation effects in the silicon dioxide layer and in fused silica. In addition to explaining the production of damage by ionization, the model has an advantage over other models inasmuch as the charge trapping in a relatively impurity‐free silicon dioxide layer can be explained. The model explains radiation‐induced charge trapping in the oxide and subsequent annealing of the charge as a function of temperature and exposure to ultraviolet radiation. In addition, the model suggests that the sensitivity of MOS devices to ionizing radiation can be reduced by decreasing the amorphous structure of the oxide.

ISSN:0021-8979    

DOI:10.1063/1.1657309

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Consideration of the factors influencing electron radiation damage has led to the development of a computer program to predict damage rates as a function of electron beam energy and crystal orientation with respect to the beam. Experimental results using low‐energy electrons (in the range 100–400 keV) are presented, which show the carrier removal rate as a function of sample orientation and electron beam energy. These measurements supplement the earlier results of Haddad and Banbury. Comparison of the calculated and experimental results enables us to make suggestions about the form of the displacement energy as a function of direction in the crystal, and to determine an effective threshold energy of 22 eV. Our model of the displacement‐energy profile is justified in a simple manner from crystallographic considerations.

ISSN:0021-8979    

DOI:10.1063/1.1657310

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An EPR study of the Mn spectra in Li‐diffused Mn‐doped GaAs is presented. The EPR spectra show that the symmetry at the Mn site is orthorhombic. This thus indicates association between the Mn and Li impurities. A model is proposed which is consistent with the observed symmetry at the Mn site, the donor impurities, and with the infrared absorption of the localized vibrational modes of the Li impurities as observed by Lorimor and Spitzer.

ISSN:0021-8979    

DOI:10.1063/1.1657311

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Photoresponse measurements were made to determine the compositional dependence of the Ga1−xAlxAs direct &Ggr;15→&Ggr;1and indirect &Ggr;15→X1energy gaps. These data, together with other information, show that the crossover composition and energy gap are between 0.35<xc<0.40 and 1.87<Egc<1.97 eV, and that the most resonable values are 0.37 and 1.92 eV.

ISSN:0021-8979    

DOI:10.1063/1.1657312

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Hall effect and resistivity of sputtered silicon‐chromium films have been measured versus temperature between −200° and +500°C on samples annealed at 550°C for 10 min. The films were dc diode sputtered at 1.0 and 2.5 kV from cathodes containing 17, 25, and 33 at.% Cr. The results are interpreted in terms of a one‐carrier conduction process, the positive Hall voltage indicating holes. The effective hole concentrationp= 1/RHqat room temperature is about 3×1021cm−3and is nearly independent of composition and sputtering voltage; it increases slightly with increasing temperature (Ea<0.1 eV). The effective mobility &mgr; =RH/&rgr;at room temperature ranges from 0.02 to 1 cm2/V·sec; it increases strongly with increasing Cr content, and decreases with increasing temperature. Small temperature coefficients of resistivity are obtained for the 25% Cr samples, where the temperature dependence of the carrier concentration cancels that of the mobility. Unannealed silicon‐chromium films have hole concentrations a factor of 2–20 higher, depending on the composition and the sputtering voltage. The mobility of unannealed films is lower by a factor of 1.2–20. As a result, annealing increases the resistivity of some films (those sputtered at 2.5 kV) and decreases it for others (those sputtered at 1.0 kV). Annealing takes place between 400° and 600°C. The low values obtained for the effective mobility are in contradiction with a basic assumption of the free carrier model. Conduction mechanisms which could account for these low values are discussed.

ISSN:0021-8979    

DOI:10.1063/1.1657313

出版商:AIP    

年代:1969

数据来源: AIP