摘要:

Rare‐earth rhodates of the distorted perovskite structure are semiconductors with a band gap of 2.2 eV. They may be doped eithernorptype. The oxides are stable against photodecomposition at the potential for hydrogen evolution. With ceramicp‐type LuRhO3as the cathode andn‐type TiO2as the anode of an electrolytic cell sufficient photopotential is developed both to photoelectrolyze water in sunlight with no externally applied potential and to generate power simultaneously. As synthesized, LuRhO3isptype as determined by thermoelectric power measurements, but may be dopedntype by the introduction of Th+4during synthesis. Electrical resistivity data show that this oxide passes through compensation as the doping level increases, the activation energy at compensation being one‐half the optical band gap. The concentration of donor and acceptor impurities was determined by magnetic susceptibility to be in the vicinity of 1% for all samples. From these data, an estimate of 2.5 cm2/V sec can be made for the mobility of holes and 1 cm2/V sec for the mobility of electrons. Unlike mostn‐type oxides reported, LuRhO3possesses deep lying impurity levels and surface capacitance is far from Mott‐Schottky behavior. We have developed a theory of surface capacitance for deep levels, and the data agree well with theory. It is interesting to note that the Fermi level of LuRhO3is pinned to the electrolyte at the same potential independent of whether the oxide isporntype.

ISSN:0021-8979    

DOI:10.1063/1.328139

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A simple theory of current flow in negative barrier metal‐insulator‐semiconductor (MIS) junctions is developed. The properties of negative barrier MIS contacts are found to be closely related to those of positive barrier MIS junctions in which the semiconductor surface is strongly inverted. It is shown that by an appropriate choice of barrier metal work function and insulator thickness it should be possible to produce a negative barrier MIS contact which does not impede the flow of majority carriers, but which acts as a surface of low effective recombination velocity for minority carriers. It is demonstrated experimentally that such minority‐carrier reflecting negative barrier contacts can provide an enhancement in solar cell open circuit voltage equal to that obtained with a diffused back surface field. This is the first report of an induced back surface field solar cell.

ISSN:0021-8979    

DOI:10.1063/1.328140

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The microstructure and properties of ZnO varistors containing Ba, Co, and rare‐earth–metal oxides, which give values of &agr; [&agr;=d(log I)/d(logV)] as high as 29, are examined. Mean ZnO grain size is 11 &mgr;m, and the grains are uniformly doped with Co. The barium and rare earth metals concentrate into 1.5‐&mgr;m‐wide particles embedded in a matrix of ZnO grains. Within the grains and at grain boundaries, the barium and rare‐earth–metal concentration is below the detection limit of the energy‐dispersive spectrometer technique (about 0.5%). No intergranular films, amorphous or crystalline, are detected, to within 10 A˚ resolution. These results are shown to be consistent with the grain boundary charge depletion model for the voltage barrier formation and breakdown.

ISSN:0021-8979    

DOI:10.1063/1.328168

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

AlxGa1−xAsp+‐n+diodes have been studied in the direct band‐gap range. Tunnel diodes were achieved in alloys with band gaps up to about 1.85 eV. For these devices theI‐Vcharacteristics show a second hump, which is believed to be due to tunneling from the conduction band on thenside of the junction to an impurity band on thepside of the junction. The location of this band was found to be independent of the band gap. In alloys with band gaps in the range 1.85–1.95 eV, backward diodes were obtained.

ISSN:0021-8979    

DOI:10.1063/1.328169

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Plasma polymerized methyl‐methacrylate thin film was formed on a glass substrate coated with chromium as a resist for electron‐beam lithography. The polymerizations were conducted at two discharge frequencies of 13.56 MHz and 5 KHz using a capacitively coupled discharge electrode system in a bell‐jar‐type reactor. Delineations were carried out using an electron beam whose diameter and acceleration voltage were 0.5 &mgr;m and 20 kV, respectively. As a test pattern, 25 pairs of parallel lines and spaces each having a 10‐&mgr;m width were delineated in a rectangular area of 0.5×0.5 mm2. Each line of 10‐&mgr;m width was depicted by sweeping over using the electron beam with 20 repetitions. The patterns were developed on the chromium by CCl4plasma etching.

ISSN:0021-8979    

DOI:10.1063/1.328170

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

In order to improve ultrasonic image quality, transducers, similar to those currently used in nondestructive testing and medical imaging applications, have been studied extensively. Attention has been given to single isolated transducers, for which anomalous radiation patterns have been obtained, and to transducers integrated in an array structure, where additional problems occur due to coupling effects between nearest neighbors. An experimental study of these phenomena has made it possible in both cases to find the origin of the perturbations with respect to the theoretical situations which occur in the radiation pattern. Solutions for increasing these perturbations are also suggested.

ISSN:0021-8979    

DOI:10.1063/1.328171

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Polycrystalline films of Sn‐substituted MnSb have been prepared from bulk by Flash evaporation. The Faraday rotations and optical absorption coefficients of MnSb1−xSnx(0⩽x⩽0.3) films are measured in the visible region. Room temperature specific saturation rotationF, decreases with increasing Sn concentration at all wavelengths while the optical absorption coefficient &agr; (uncorrected for reflection) does not show any significant change. The Magneto‐optic figure of merit (2F/&agr;) for different compositions and wavelengths are estimated for evaluating these films as beam‐addressable storage elements.

ISSN:0021-8979    

DOI:10.1063/1.328172

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A theoretical model for aninsituoil shale retort with three distinct vertical zones, all surrounded by a wall of oil shale, overburden and underburden, is considered for the study of potential electromagnetic monitoring of the progression of retorting processes using wave propagation techniques. The overall power reflection and transmission coefficients for both transverse electric and transverse magnetic waves are used for finding the position of a combustion zone in the retort, based upon the assumption of straight‐line propagation of monochromatic plane waves through layered lossy dielectric media characterized by the dielectric constants and loss tangents. The behavior of each power coefficient is discussed as a function of burn front positions and signal frequencies. As a result of the relatively moderate signal power for each coefficient required for detection, and the one‐to‐one correspondence between each power coefficient and burn front position at typical conditions, the feasibility of using low radio‐frequency waves to monitor relatively large scaleinsituretorting process is established.

ISSN:0021-8979    

DOI:10.1063/1.328173

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An experimental investigation has demonstrated that the previously observed wall‐supported shock precursor, in high‐explosive‐driven argon‐containing shock tubes, rapidly grows to a maximum length at a tube length‐to‐diameter ratio of 2. It then gradually decreases in length and grows in width as a steady‐state configuration is apparently asymptotically approached. All experiments were done in 10.2‐cm tubes varying in length from 10 to 80 cm. The explosive was Comp C‐4, and the exterior surface of the tube was surrounded by a 4‐mm‐thick layer of Deta‐sheet to minimize wave attenuation. The experimental assembly was tamped in sand. The precursor was observed with a smear camera as the wave system interacted with a thin aluminum foil covering the end of the tube.

ISSN:0021-8979    

DOI:10.1063/1.328174

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

X‐ray and diamagnetic loop measurements following electron beam injection into a hot ion plasma trapped in a minimum‐Bmirror system are reported. The hot electrons, believed to be responsible for the novel stabilization of the plasma by electron beam injection, are found to have a temperaturekT∼2–3 keV, and a density of about 1% of the plasma’s at the midplane. Axially, the hot electrons are more widely distributed than the trapped ions.

ISSN:0021-8979    

DOI:10.1063/1.328175

出版商:AIP    

年代:1980

数据来源: AIP