摘要:

Aderivedcurrent‐voltage (I‐V) characteristic forp‐nheterojunction solar cells of the form window/absorber is obtained. The development lends itself to a simple, diagrammatical interpretation of the step‐by‐step collection of the photocurrent flowing out of the base of the absorber. The resulting generalI‐Vcharacteristic under illumination is in a form useful for the design of these devices and for the interpretation of their performance.

ISSN:0021-8979    

DOI:10.1063/1.327883

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Measurements of the weak‐field magnetoresistance (WFMR) were carried out at 300 and 77 K on two (111)‐orientedn‐type PbTe epitaxial films, 4 and 10 &mgr;m thick. A recently developed single‐sample four‐measurement technique and a cubic‐trigonal‐hexagonal extension of the Seitz–Pearson–Suhl WFMR phenomenology were used to obtain and analyze the data. Significant deviations from the requirements of cubic symmetry were detected, the effect being larger in the thinner film and at the lower temperature. A WFMR coefficient ratio, which would have been unity for a cubic environment, ranged from 1.3 to 6.8. These noncubic results are tentatively ascribed to the effects of substrate‐induced strain on the films. The four WFMR coefficients were fitted to a simple trigonally distorted three‐parameter model of the PbTe conduction band. For reasons not yet identified, the fit was very good for the thinner film and quite poor for the other one.

ISSN:0021-8979    

DOI:10.1063/1.327884

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

From an investigation of the behavior of the momentum distribution function of electrons or holes under scattering rate and momentum scaling transformations, a number of interesting results are derived concerning the parameterization of drift‐velocity–vs–electric‐field relations in terms of mobility and saturation velocity. Indeed it is determined that saturation velocity is invariant under scaling of the magnitude of the scattering rates, which alters mobility, while mobility is invariant under scaling of the magnitude of the momentum, which alters saturation velocity. This independence between mobility and saturation velocity is utilized to generalize to interfaces velocity‐field relations valid the the bulk. Using the transformation of drift velocity under both rate and momentum scaling, partial experimental data can be used to predict high‐field saturation velocities. These velocities need not be reduced due to higher scattering rates as much as their low‐field counterparts. Nonzero magnetic fields and nonuniform scaling are also considered.

ISSN:0021-8979    

DOI:10.1063/1.327885

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Improvement of the previously reported photocapacitive MIS infrared detectors has led to the development of exceptional room‐temperature devices. Unoptimized peak detectivities on the order of 1013W−1cm Hz1/2, a value which exceeds the best obtainable from existing solid‐state detectors, have now been consistently obtained in Si and GaAs devices using high‐capacitance LaF3or composite LaF3/native‐oxide insulating layers. The measured spectral response of representative samples is presented and discussed in detail together with a simple theory which accounts for the observed behavior. The response of an ideal MIS photocapacitor is also contrasted with that of both a conventional photoconductor and ap‐i‐nphotodiode, and reasons for the superior performance of our detectors are given. Finally, fundamental studies on the electrical, optical, and noise characteristics of our MIS structures are analyzed and discussed in the context of infrared‐detector applications.

ISSN:0021-8979    

DOI:10.1063/1.327886

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Measurements were made of the capacitance (1 kHz) and the dc conductivity of degassed, oxygen‐doped, and iodine‐doped single crystals of lead phthalocyanine (PbPc) as a function of temperature between room temperature and 250 °C. As the temperature was increased, the capacitance initially remained constant as expected, followed by an exponential increase similar to that of the conductivity and then saturated with an extraordinarily large value. Frequency dependence below 1 MHz of the capacitance and the loss tangent of PbPc film with aluminium electrodes was also measured at degassed and oxygen‐doped states. An apparent Debye‐type dispersion was observed. All the results obtained are consistently understood in terms of the Schottky barrier capacitance associated with the PbPc‐electrode contact. The oxygen doping exhibited remarkable influence on the alternating current response and this effect is considered to be due to changes in the barrier capacitance and the dc conductivity with doping.

ISSN:0021-8979    

DOI:10.1063/1.327887

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The potential barriers of ultrathin (%40 A˚) SiO2layers to electrons and holes tunneling between the semiconductor and the metal have been measured independently on the same MOS samples by a new experimental technique introduced in this paper. The method combines dark measurements of current and capacitance versus voltage with measurements of photocurrent suppression under optical illumination. The results show that the tunneling barriers for holes are consistently much larger than those for electrons.

ISSN:0021-8979    

DOI:10.1063/1.327888

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

It is shown that the energy of electronic minority charge carriers injected into an electrolyte from an illuminated semiconductor electrode may be significantly greater than that predicted by previous models. The time constants for tunneling from the semiconductor states in the depletion region are evaluated by two methods: approximating the final states as a continuum resulting from strong electron‐vibration interaction in the electrolyte, and calculating the oscillation time between semiconductor states and the discrete electrolyte states before vibrational relaxation. Comparisons are made with the time constants for intraband electronic relaxation in the semiconductor, including the effects of quantization due to confinement in the depletion region, and with those for the vibrational relaxation in the electrolyte. The general conditions for the injection of hot carriers from semiconductors into electrolytes are specified.

ISSN:0021-8979    

DOI:10.1063/1.327889

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Recently, Rodriquez and co‐workers [J. Appl. Phys. 50, 6011 (1979)] reported anomalous photocurrent in reverse‐biased tin oxide/silicon solar cells. We have observed no anomalous photocurrent in our indium tin oxide/silicon semiconductor‐insulator‐semiconductor (SIS) solar cells. In this paper we have offered a possible explanation of why the authors of the above referred paper have observed anomalous photocurrent in tin oxide/silicon solar cells whereas no such effect has been observed in our indium tin oxide/silicon SIS solar cells.

ISSN:0021-8979    

DOI:10.1063/1.327890

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Nearly ’’stoichiometric’’ amorphous silicon carbide films were prepared by the reactive sputtering of a silicon target in a gaseous mixture of Ar, CH4, and H2(or D2). The use of the1H (11B, &agr;)&agr;&agr; nuclear reaction and infrared transmission measurements shows that controlled amounts of hydrogen can be incorporated in the films during deposition. The hydrogen content has a dominant effect on the density of the films, its optical gap, and its refractive index. The films could be well described as a polycarbosilane, made of CHn, SiH, and SiC groups. Moreover,11B bombardment induces a decrease of the hydrogen content and a drastic change in the bonds of the polycarbosilane. In conclusion, we show that reactive sputtering is an alternative to the glow discharge technique previously described by W.E. Spear to obtain amorphous silicon carbide.

ISSN:0021-8979    

DOI:10.1063/1.327891

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The properties of indium‐tin oxide (ITO)/CdTe junction solar cells prepared by rf sputtering of ITO onP‐doped CdTe single‐crystal substrates have been investigated through measurements of the electrical and photovoltaic properties of ITO/CdTe and In/CdTe junctions, and of electron beam induced currents (EBIC) in ITO/CdTe junctions. In addition, surface properties of CdTe related to the sputtering process were investigated as a function of sputter etching and thermal oxidation using the techniques of surface photovoltage and photoluminescence. ITO/CdTe cells prepared by this sputtering method consist of ann+‐ITO/n‐CdTe/p‐CdTe buried homojunction with about a 1‐&mgr;m‐thickn‐type CdTe layer formed by heating of the surface of the CdTe during sputtering. Solar efficiencies up to 8% have been observed withV0c=0.82 V andJsc=14.5 mA/cm2. The chief degradation mechanism involves a decrease inV0cwith a transformation of the buried homojunction structure to an actual ITO/CdTe heterojunction.

ISSN:0021-8979    

DOI:10.1063/1.327892

出版商:AIP    

年代:1980

数据来源: AIP