摘要:

The minority carrier diffusion lengths on both sides of Cu2S&sngbnd;CdS heterojunctions have been measured directly by light microprobe techniques. In approximately 1 &OHgr; cm CdS the hole diffusion length was found to be between 3×10−4and 7×10−4cm. The high‐conductivity Cu2S formed on the CdS by a chemical dip was found to have electron diffusion lengths ranging from ≤1×10−5to 4×10−5cm. Light‐induced breakdown was observed at small reverse bias for photon energies greater than the CdS bandgap. The reverse breakdown was correlated with visible defects on the junctions where photocurrent gains as large as 2000 were observed. A model for the breakdown is proposed in which Zener breakdown at high‐field points along the junction is modulated by photoinjected holes.

ISSN:0021-8979    

DOI:10.1063/1.1659093

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A discharge plasma is established in air at pressures of 0.2–20 Torr in the rf electric field between parallel‐plate electrodes in a resonant circuit at 14 MHz. By adjusting a calibrated tuning capacitor in parallel with the electrodes, one can observe a wide range of plasma conditions extending from normal extinction at low rf potential and power to an apparent dynamic instability at high potential and power. The loading effect of the plasma is found to be that of a lossy capacitance. Net input rf power to the plasma‐loaded circuit at the tuning condition just below the threshold for dynamic instability is found to be ∼10 times that for a plasma maintained at the tuning condition for the resonant circuit without plasma. The retuning effects are discussed on the basis of the nonlinearity of the plasma medium, and a possible mechanism for the dynamic instability is proposed.

ISSN:0021-8979    

DOI:10.1063/1.1659094

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Mass identified measurements of the time dependence of the density of atomic argon ions in decaying plasmas are reported. The measurements yield a mobility &mgr;0(Ar+)=1.55 cm2V−1·sec−1for Ar+in argon at a gas temperature of 300°K, and for the rate of conversion of Ar+into Ar2+, a value of 1.9×10−31cm6sec−1.

ISSN:0021-8979    

DOI:10.1063/1.1659095

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The validity of electron‐density determinations using spherical probe in medium pressure discharge plasmas (rp/&lgr;e∼0.3 to 40, whererp=probe radius, &lgr;e=electron mean‐free path) are examined for density rangeNe=109−1011cm−3. Various collision‐dominated probe theories are used to obtainNefrom both electron and ion saturation currents (IeandIi).Nedetermined fromIecoincide reasonably with those determined from microwave measurement, whileNefromIiare always greater than those from microwave measurement by a factor of 2 to 100. The discrepancy increases with increasing gas pressure and total discharge current, andIican not be used forNedeterminations. There is ``break'' on the ion current characteristics which is the same as that reported in the measurement of very low‐density flowing afterglow plasmas (Ne<108cm−3). Explanation is offered in connection with the unusual increase of ion current caused by the release of electrons from the probe surface by collisions of metastables and the decrease of regular thermal‐motion current because of the short mean‐free path condition (&lgr;6<rp).

ISSN:0021-8979    

DOI:10.1063/1.1659096

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Calculations of the absorption coefficients for inverse bremsstrahlung in the field of ions and neutral atoms in ground and excited states and for photoionization are presented for the absorption of He&sngbnd;Ne laser radiation in dense Li plasmas. These are compared with those measured in an exploded Li‐wire plasma and the two values differ at most by a factor of five. The electron density and temperature in the plasma are estimated from the time‐resolved spectroscopic measurements using the Stark broadening of the Li 6103 line and the intensity ratios of various neutral and ionized Li lines. The plasma diameter and the total neutral atom densities are estimated from the framing and streak pictures of the plasma.

ISSN:0021-8979    

DOI:10.1063/1.1659097

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The effects of ion implantation in an MOS structure were investigated. It was found that depending on the choice of implantation parameters, the effects may include: (1) displacement damage in the oxide, (2) creation of fast states and positive fixed charge near the Si/SiO2interface, and (3) doping in the substrate. MOS capacitance measurements, used in conjunction with isothermal annealing, indicate that the fast states are located in the center of the forbidden gap and are most likely physically associated with point defects created by implantation. In O+implanted specimens, a residual positive charge was formed after an annealing treatment which removed the fast states. The residual charge is probably attributable to a reoxidation effect during annealing.

ISSN:0021-8979    

DOI:10.1063/1.1659098

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Sputtering of gold by normally incident protons of energies between 500 eV and 8 keV has been studied. An ion source system delivering a magnetically analyzed proton beam to a target at a pressure of 5×10−8Torr was utilized, and neutron activation established the quantities of sputtered material. The gold targets, consisting of microcrystals with preferred orientation, were sputtered predominantly on (100) and (110) planes, and the yields were not observed to depend perceptibly on the crystal orientation. The yield was a maximum of 0.022 atoms/proton at a proton energy of 4 to 5 keV, dropping off gradually at higher energies and sharply at lower ones. Analysis of the sputtered deposit spot patterns, using autoradiographs, indicated that focused collision sequences were of greater importance in proton sputtering than in sputtering by heavier ions. A readily detectable yield for sputtering by 500‐eV protons suggests a minimum atomic ejection energy of less than 10 eV for sputtering of gold.

ISSN:0021-8979    

DOI:10.1063/1.1659099

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A time‐dependent differential equation for the average conduction current density in a semiconductor avalanche has been derived in the quasistatic approximation. For generality, unequal ionization rates and drift velocities have been assumed. The functional form of the resulting differential equation is simplified by introducing macroscopic quantities like the multiplication and the intrinsic response time. It is shown that in obtaining the correct quasistatic limit the carrier‐induced displacement current must be included, since this current modifies the intrinsic response time and also gives rise to a reactive term. Simplified analytical expressions are obtained for correction factors due to these effects in special cases, e.g., like assuming the ratio between the ionization rates to be independent of the electric field. The modification of the intrinsic response time is shown to be of special importance in the design of avalanche photodiodes. Analytical design criteria for such diodes are given. The small‐signal admittance is derived and compared with experimental susceptance measurements. It is shown that a special plot of the data can give a fairly accurate determination of the intrinsic response time, since this plot allows systematic experimental errors to be removed.

ISSN:0021-8979    

DOI:10.1063/1.1659100

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

An analytical development is given for multifrequency operation of avalanche diodes with a narrow ionization layer. The current response from the avalanche is evaluated in the quasistatic limit. The continuity equations are solved separately in the drift regions. The efficiency at the lowest harmonic is derived. It is found to be necessary to limit the generation of carriers due to the positive space‐charge resistance of the drift regions. The theoretical results are used to analyze two‐frequency operation of two Read diode structures. The analytical approach is quite simple at small and intermediate perturbations. An analog computer program was developed to calculate large signal perturbations. For an effective avalanche width of 0.69‐&mgr; optimum efficiencies of 23&percent; and 34&percent; are predicted for single and two‐frequency operation, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1659101

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The capacitance‐voltage (C‐V) relationship of a Schottky barrier diode is predicted for an energy distribution of impurity levels having spatially uniform concentration in ann‐type semiconductor. The model applies for forward and reverse bias voltages at modulation frequencies near dc and at modulation frequencies at which one or more of the deep doping levels cannot respond. Effects of partial ionization of impurity species and the effect of electrons in the depletion region are considered. It is predicted that the diode [d(1/C)/dV] versusVrelationship exhibits sharp minima when the barrier height minus the applied bias is equal to the energy level relative to the conduction band edge of any of the predominant deep‐lying impurities in the semiconductor. The way in which deep lying impurities consequently affect aC‐Vimpurity profile analysis is discussed.

ISSN:0021-8979    

DOI:10.1063/1.1659102

出版商:AIP    

年代:1970

数据来源: AIP