Vapor Phase Growth Technique and System for Several III-V Compound Semiconductors Interim Scientific Report
Vapor phase crystal growth and preparation of gallium, indium, arsenic, phosphorous, and antimony alloy semiconductor materials
Clough, R.↗
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Microwave device investigations Semiannual progress report, 1 Apr. - 1 Oct. 1969
Summaries of progress in beam plasma interactions, paramagnetic and bulk semiconductor materials, and avalanche diodes
Curtice, W. R.↗
Gd or Sm doped silicon semiconductor composition Patent
Gadolinium or samarium doped-silicon semiconductor material with resistance to radiation damage for use in solar cells
Mandelkorn, J.↗
A study of metal insulator semiconductor magnetoresistance, bulk, and surface properties of indium antimonide
Metal-insulator-magnetoresistance, bulk, and surface properties of indium antimonide compound semiconductor material
Grannemann, W. W.↗
Vapor phase growth system and its use in the preparation of several III-V compound semiconductors
Vapor phase growth and properties of semiconductor materials
Enstrom, R. E.↗
A summary of the research program in the broad field of electronics
Summary reports of research projects covering solid state materials, semiconductors and devices, quantum electronics, plasmas, applied electromagnetics, electrical engineering systems to include control communication, computer and power systems, biomedical engineering and mathematical biosciences.
Source record↗
Influence of gravity-free solidification on microsegregation
Single crystalline germanium has been grown for the first time in space aboard Skylab Mission No. 2. The crystal growth experiment, designed to characterize the influence of gravity-free solidification on microsegregation of a semiconductor material, contained three crystals. One was doped with Ga; the second with Sb; and the third with B. Portions of the germanium crystals were remelted and subsequently resolidified at 5 microns per second under controlled conditions by the gradient freeze technique. Detailed spreading resistance measurements made on the Ga doped Ge crystals indicate that microsegregation in space is reduced by two to five-fold in the bulk and eight-fold near the surface, while macrosegregation in space is reduced by six-fold in the bulk. The effective segregation coefficient for Ga in Ge was analyzed extensively and was found to be larger for space solidification. This has the implication that the solute boundary layer at the growth interface in space is correspondingly thinner. The solidification interface is significantly smoother and is found to be initially convex toward the melt in space. A convective mixing model has been advanced to explain the absence of gravity on convective mixing and solute segregation during solidification.
Yue, J. T.↗
Contact-eutectic-lens fabrication technique
Method enables use of crystal or semiconductor materials with selective spectral-response characteristics (ultraviolet, visible, or infrared wavelengths) in fabrication of contact lenses, reading glasses, and photographic processing equipment.
Allen, F. G.↗
Electromagnetic radiation screening of microcircuits for long life applications
The utility of X-rays as a stimulus for screening high reliability semiconductor microcircuits was studied. The theory of the interaction of X-rays with semiconductor materials and devices was considered. Experimental measurements of photovoltages, photocurrents, and effects on specified parameters were made on discrete devices and on microcircuits. The test specimens included discrete devices with certain types of identified flaws and symptoms of flaws, and microcircuits exhibiting deviant electrical behavior. With a necessarily limited sample of test specimens, no useful correlation could be found between the X-ray-induced electrical response and the known or suspected presence of flaws.
Brammer, W. G.↗
Semiconductor ohmic contact
Contact formed on p-type surface of semiconductor laser has several advantages: highly conductive degenerate region and narrow band gap provides surface for good metal-to-semiconductor contact; lattice parameter of GaAs is 5.6533 A; improved lattice match eases interface strain which reduces interface cracking of semiconductor material.
Hawrylo, F. Z.↗
III-V photocathode with nitrogen doping for increased quantum efficiency
An increase in the quantum efficiency of a 3-5 photocathode is achieved by doping its semiconductor material with an acceptor and nitrogen, a column-5 isoelectronic element, that introduces a spatially localized energy level just below the conduction band similar to a donor level to which optical transitions can occur. This increases the absorption coefficient, alpha without compensation of the acceptor dopant. A layer of a suitable 1-5, 1-6 or 1-7 compound is included as an activation layer on the electron emission side to lower the work function of the photocathode.
James, L. W.↗
X-ray topography as a process control tool in semiconductor and microcircuit manufacture
A bent wafer camera, designed to identify crystal lattice defects in semiconductor materials, was investigated. The camera makes use of conventional X-ray topographs and an innovative slightly bent wafer which allows rays from the point source to strike all portions of the wafer simultaneously. In addition to being utilized in solving production process control problems, this camera design substantially reduces the cost per topograph.
Parker, D. L.↗
Novel silicon crystals and method for their preparation
Plate shaped silicon crystals and their preparation by pouring a silicon melt into a suitable mold and then allowing it to solidify in a temperature gradient were investigated. The production of energy by direct conversion of solar energy into electrical energy by means of solar cells takes on increasing importance. While this type of energy production is already the prevailing form today in the realm of satellite technology, its terrestrial application has thus far encountered strict limitations owing to the high price of such solar cells. Of the greatest interest in this connection are silicon cells. A substantial reduction in the semiconductor material costs and the costs involved in the further processing to make solar cells are prerequisites for a rational market growth for solar energy.
Authier, B.↗
Space-charge-limited solid-state triode
A solid-state triode is provided from a wafer of nearinstrinsic semiconductor material sliced into filaments of rectangular cross section. Before slicing, emitter and collector regions are formed on the narrow sides of the filaments, and after slicing gate regions are formed in arrow strips extending longitudinally along the midsections of the wide sides of the filaments. Contacts are then formed on the emitter, collector and gate regions of each filament individually for a single filament device, or in parallel for an array of filament devices to increase load current.
Shumka, A.↗
A review of Air Force high efficiency cascaded multiple bandgap solar cell research and development
At the time of their conception, the cell stack systems to be discussed represent the best semiconductor materials combinations to achieve Air Force program goals. These systems are investigated thoroughly and the most promising systems, from the standpoint of high efficiency, are taken for further development with large area emphasized (at least 4 sq cm). The emphasis in the Air Force cascaded cell program is placed on eventual nonconcentrator application. This use of the final cell design considerably relieves the low resistance requirements for the tunnel junction. In a high concentration application the voltage drop across the tunnel junction can be a very serious problem.
Rahilly, W. P.↗
The role of thermophysics in the design, optimization and understanding of semiconductor crystal growth in space
The compound semiconductor material PbSnTe has been investigated by NASA Langley Research Center as part of the Material Processing in Space (MPS) experiment in the framework of the Space Shuttle program. The long-range goal of the research is the improving of the performance of infrared detectors for use in remote sensing experiments. Three distinct techniques will be used in the low-g environment of space: two techniques involving bulk growth from melt and a vapor growth technique. In order to establish realistic estimates of the required time for experiments and to determine the thermal gradients that will be required to avoid constitutional supercooling, the diffusion coefficients must be accurately measured, however more data especially in the vapor-solid phase relations are needed.
Crouch, R. K.↗
Analysis of the interaction of an electron beam with a solar cell. III - The effect of spacial variations of the number density of recombination centers on SEM measurements
By means of an exactly soluble model the short circuit current generated by a scanning electron microscope in a P-N junction has been determined in cases where the trap density is inhomogeneous. The diffusion length for minority carriers becomes then dependent on the spacial coordinates. It is shown that in this case the dependence of the Isc on characteristic parameters as cell thickness, distance of the beam excitation spot from ohmic contacts, etc., becomes very intricate. This fact precludes the determination of the local diffusion length in the usual manner. Although the model is somewhat simplified in order to make it amenable to exact solutions, it is nevertheless realistic enough to lead to the conclusion that SEM measurements of bulk transport parameters in inhomogeneous semiconductor material are impractical since they may lead to serious errors in the interpretation of the data by customary means.
Von Roos, O.↗
Bulk lifetime indicates surface contamination
Indirect measurement of wafer surface impurities has sensitivity of 300 monolayers. Photoconductivity-decay apparatus determines bulk recombination lifetime in semiconductor materials. Bulk impurity levels before and after annealing relate to level of surface contamination. Method evaluates wafer cleaning techniques, qualifying purity of chemical and deionized water used, or monitors production process.
Blais, P. D.↗