摘要:

An expression for the distribution over tetrahedral and octahedral sites of constituent cations and cation vacancies has been derived in copper ferrites Cu1−&dgr;Fe2+&dgr;O4+&ggr;, where &dgr;?0.5 and &ggr;≳0. According to the derived distribution, the calculated saturation magnetization and Seebeck coefficient are in satisfactory agreement with the observed values in copper ferrites Cu0.52Fe2.48O4+&ggr;quenched from 1250 °C under various oxygen partial pressures. These results indicate that no cation vacancy is generated in tetrahedral site but only in octahedral site even at high temperatures.

ISSN:0021-8979    

DOI:10.1063/1.329978

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We present simple analytic expressions for the classical energies of previously obtained nonlinear‐standing‐wave and single‐soliton solutions to the sine‐Gordon equation for a finite‐length system with fixed‐ and free‐boundary conditions. Plots of these energies are presented for several system lengths and the energy expressions are shown to reduce to those appropriate to familiar solutions in the infinite system as the length approaches infinity.

ISSN:0021-8979    

DOI:10.1063/1.329979

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A study of the internal yield, depletion width, and absorption constant is presented for dc glow dischargeP‐I‐Namorphous silicon films. Internal yields of ∼0.9 at 475 nm and depletion widths as large as 0.37 &mgr;m were observed at low illumination levels and were characteristic of the better cells. The absorption constant as a function of wavelength showed no anomalies and was comparable to rf glow discharge films with an optical gap of 1.68 eV. A unique aspect of these cells is that the topPlayer is amorphous boron.

ISSN:0021-8979    

DOI:10.1063/1.329980

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The open circuit voltage, fill factor, and power conversion efficiency ofn‐CdSe thin‐film electrodes for photoelectrochemical solar cells have been improved by treating the surface with Zn++ions. The overall efficiency of these electrodes was increased from ∼5% to as high as 6.5% with a soaking treatment in 1MZnC12. Photoelectrochemical measurement and Auger spectroscopy indicated the observed improvements were the result of a shift in the flat‐band potential to more negative values due to the incorporation of zinc into the surface region of the CdSe thin film.

ISSN:0021-8979    

DOI:10.1063/1.329981

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A computer model to simulate an+ip+amorphous silicon solar cell was developed. This model is based on the computer simulations of solar cells by T. Chappell and the Read diode by Scharfetter and Gummel. The model is used to generate field plots, band diagrams, quantum efficiency curves,I‐Vcharacteristics, carrier density distribution plots, carrier generation, and carrier recombination plots. The simulated values of short circuit current density, open circuit voltage, fill factor, efficiency, junction quality factor, quantum efficiency, junction quality factor, quantum efficiency, slope ofI‐Vcurves atV= 0 andV=Vocare in good agreement with the measured cell values. Computer simulation shows that a major loss mechanism is the back diffusion of holes into then+layer which is diminished by a strong electric field provided by a high concentration of ionized donors in then+layer. Projection of cell performance based on the production ofn+andp+contact layers with ionized donor and ionized acceptor concentrations in the 2×1020cm−3range indicates cell efficiencies greater than 10%.

ISSN:0021-8979    

DOI:10.1063/1.329963

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Au‐interfacial oxide layer (GeO2, Sb2O3, Bi2O3, SnO2and native oxide mixture of AS2O3and Ga2O3)‐semiconductor (GaAs) structures were investigated by the Auger Electron Spectroscopy Method. The results of depth profiling with Ar+‐ion sputtering are presented for all metal‐insulator‐semiconductor (MIS) structures. ’’Metal’’ atoms from deposited interfacial oxide layers (Ge from Ge2O3, Sb from Sb2O3, Bi from Bi2O3, and Sn from SnO2) were observed on the surface. Only As atoms were observed for the native oxide mixture of As2O3and Ga2O3interfacial layer. These findings suggest that As2O3is the dominating oxide at the metal‐oxide interface for native oxide GaAs MIS solar cells. The interfacial reaction takes place between Au and the interfacial layer at room temperature. The ’’diffusion’’ of metal atoms from the interfacial layer towards the surface is suspected to play a role in degradation effect in GaAs MIS solar cells.

ISSN:0021-8979    

DOI:10.1063/1.329982

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A model is introduced to describe the transverse electromagnetic propagation of power in high‐voltage vacuum transmission lines in the presence of a resistive cathode plasma. The model consists of the transmission line equations complemented with a one‐dimensional model for calculating local shunting currents. These equations are self‐consistently solved in the presence of a cathode plasma expanding against the magnetic field. The plasma motion, considered to start at a given point when the local electric field reaches the selected threshold value of 0.3 MV/cm, is described by using one‐dimensional magnetohydrodynamic equations in which the plasma properties at each position along the length of the line are assumed to depend only on the cross cathode‐anode direction. Magnetic diffusion is taken into account in the plasma as well as in the metal cathode. The model is applied to a system for which experimental results are available: a 2‐m vacuum coaxial line of Al walls, driven by a voltage pulse of 130‐ns duration and 0.5‐MV peak, of 6.2‐cm radius and 0.5‐cm gap terminated by an 18‐nH inductive load. Several calculations with different initial temperatures and densities were performed assuming an Al plasma in local thermal equilibrium of variable degree of ionizationz¯.For the highest initial values of temperature and areal density used,T= 5 eV, &mgr; = 8.7×10−7g/cm2, the average plasma front velocity was 2.4×106cm/s. For this case the plasma is found to carry about 50% of the line current once its size is of the order of 1 mm, and it is almost stopped by the magnetic field, which reaches 25 kG at 130 ns. The calculated values of the line and shunting currents at different positions along the coax are compared with the experimental values. It is shown that the line currents are higher than if no plasma were present and lower than if it were a moving perfect conductor. For lower temperatures and densities, the average plasma front velocities are lower, of the order of 2×106cm/s. To assess the possible influence of anomalous effects anadhocmodel for resistivity, in which it is equal to the inverse of the electron plasma frequency, is introduced. ForT= 5 eV and &mgr; = 8.7×10−7g/cm2, thisadhocmodel which clearly underestimates the influence of the magnetic field in slowing down the plasma, gives average plasma front velocities of 3.5×106cm/s. On the basis of these calculations, it is concluded that for the type of experimental setup under consideration, no plasma closure should be observed, even when active loads are used, within the framework of the physical phenomena considered here. The importance of considering magnetic diffusion and joule heating in the motion of the cathode plasma as it influences the electrical properties of vacuum lines is demonstrated.

ISSN:0021-8979    

DOI:10.1063/1.329937

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We analyze, in the absence of space charge, nonaxisymmetric wave propagation in pulsed power machines in the long wavelength limit (&lgr;≫anode‐cathode gap dimensions). The conditions for generalized TEM waves are derived for both straight (coaxial) and convergent (double‐disk) transmission lines. We examine the asymmetries resulting from the lack of switch synchronization as it affects the wave propagation and power delivery to a small radius symmetric imploding load. We apply the long wavelength equations to the output water line and vacuum feed sections of a machine resembling BLACKJACK V and calculate the reduction in power delivered to the load as a function of the degree of synchronization. An important, but simple, consequence of the theory is that for a small symmetric load the angular average of the voltage at the switches is approximately the effective driver of the power reaching the load.

ISSN:0021-8979    

DOI:10.1063/1.329938

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have performed a transient analysis of a Josephson interferometer in which feedback has been introduced to sharpen the transfer function. We examine the case for junctions with small, but finite, capacitance, so that the junctionI‐Vcharacteristics have a small hysteresis. We find that no significant changes in switching times occur when feedback is introduced. The transfer function for the interferometer calculated in our ac analysis, which includes finite junction capacitance, is somewhat different from the one determined by a simple dc analysis that assumed zero capacitance.

ISSN:0021-8979    

DOI:10.1063/1.329939

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The growth and characterization of tunneling GaAs homojunctions and GaAs‐AlGaAs heterojunctions by molecular beam epitaxy for use as optically transparent interconnects in GaAs and AlGaAs solar cells is described. GaAs tunneling interconnects have been achieved with conductances of 300 A/cm2‐V at 0.050 V, and p‐AlxGa1−xAs/n‐GaAs heterojunction structures withxup to 0.4 have been grown which have characteristics comparable to GaAs interconnects. Thin interconnects, 1000 A˚ total thickness, have also been fabricated with conductances comparable to thicker junctions. The effect of dopant diffusion was found to be minimal at the 580 °C junction growth temperature, but annealing these tunnel junctions at 650 °C for several minutes caused diffusion of about 100 A˚ distance.

ISSN:0021-8979    

DOI:10.1063/1.329940

出版商:AIP    

年代:1982

数据来源: AIP