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This report summarizes the results of the experimental and theoretical efforts aimed at developing new image quality descriptors suitable for performance prediction and optimization of combined display-observer systems. The approach is that of linear systems analysis, using the methodology of statistical communications theory. The authors treat the processes of image display and perception in statistical terms and predict the most probable performance of the overall observer-imaging system. This report contains a number of important new results concerning the statistical properties of natural scenes, a complete, new, statistical treatment of the one-dimensional image sampling problem, a new descriptor suitable for the analysis of the perceived sharpness of two-dimensional analog (nonsampled) displays having nonisotropic point-spread functions, and data obtained from a set of psychophysical measurements aimed at the quantitative understanding of the two-dimensional sine wave response of human visual perception. The authors also report the development of a real-time optical block image processor that was developed for use for the experimental testing of our theoretical results.

A method for fabricating and processing plated heat sink hyperabrupt gallium arsenide varactors for use in microwave voltage-controlled oscillators was developed and evaluated during this program. VCOs fabricated with these varactors demonstrated considerably improved linearity and reduced tuning voltage requirements as compared with VCOs fabricated with conventional abrupt junction varactors. During the program, hyperabrupt gallium arsenide varactor wafers were grown in which values of gamma from 0.5 to 2.0 were obtained and capacitance ratios as high as 30:1 were measured. In most cases, the carrier concentration profiles necessary to obtain the various hyperabrupt characteristics obtained were grown epitaxially by the hydride vapor synthesis technique using a programmed controller to introduce dopant at the required rates. The process was proven to have the capability to grow wafers which closely matched a desired profile. Because of the versatility of this controlled back-doping process, complicated structures can be grown such as the p(+)-n(o)- n(+)-n-p(+) GaAs wafers which were used to produce electrolytically etched varactor diodes with integral heat sinks. These plated heat sink mounted varactors proved to have very low post tuning drift characteristics in VCOs compared with conventionally mounted GaAs varactors.

Research effort was directed at validating the concept of using a handheld, battery operated, cw microwave radar, operating at 2.45 GHz, for use as a heart rate monitor under chemically contaminated battlefield conditions. Verification of radar measurements under laboratory conditions was made by literature references and laboratory demonstrations. A breadboard system was designed and evaluated with relatively good results for prone, stationary patients, but erratic performance, probably caused by reflections from antenna side leakage, was observed during transport in a tracked vehicle outfitted as an ambulance. Some circuit modifications and improved shielding are recommended for Phase II prototype models.

Basic requirements for obtaining injection laser action in III-V semiconductors are discussed briefly. A detailed review is presented of materials suitable for lasers emitting at 0.67, 1.44, 1.93, and 2.5 micrometers. A general approach to the problem is presented, based on curves of materials properties published by Sasaki et al. It is also shown that these curves, although useful, may need correction in certain ranges. It is deduced that certain materials combinations, either proposed in the literature or actually tried, are not appropriate for double heterostructure lasers, because the refractive index of the cladding material is higher than the index of the active material, thus resulting in no waveguiding, and high threshold currents. Recommendations are made about the most promising approach to the achievement of laser action in the four wavelengths mentioned above. Keywords: Lasers; Refractive Index; Bandgap.

Several double heterostructure injection lasers were fabricated from vapor-grown InGaAs P/InP. Laser wavelength was 1.4 micrometer. The lowest threshold current density observed was 2385 A/sq.cm. The etching characteristics of bromine-methanol-phosphoric acid solutions on InP were tabulated., Sponsored in part by DARPA.

The objective of this program is to develop techniques for the vapor- phase growth of high-resistivity epitaxial layers of gallium arsenide on semi- insulating gallium arsenide substrates. A capability to grow such layers of high-quality material with minimum structural defects and good surface quality for use as buffer layers prior to the growth of active layers for such devices as FETs and TELDS will eliminate the device performance problems caused by poor and inconsistent substrate quality. During the first quarter, a vapor-phase GaAs reactor and its associate gas handling system were designed and constructed. Preliminary test runs were performed to check system operation under normal operating conditions. In the second quarter, both undoped and Cr-doped high- resistivity GaAs epitaxial layers were grown. The surface morphology of the high-resistivity layers was excellent. During the second quarter, the investigation of a number of techniques was begun in order to develop a capability for characterizing both substrate material and high-resistivity epitaxial layers. This report will describe progress in all of these areas.

This report is concerned with the visibility of displayed luminance information, that is, predicting what an observer can see when he views a display. Some of the specific practical problems addressed are: When does a change in display modulation transfer become visible. What are the perceptual effects of sampling and a visible raster structure. How does the perceived information vary with display signal-to-noise ratio. What perceptual effect does a change in display luminance have on the perceived information. And, finally, what display conditions are required in order to produce a perceptually 'perfect' displayed image.

Varactor-tunable resonant filter elements that use the negative resistance of an FET to overcome the losses of the varactor and the circuit were used to construct two two-section filters. The two filters operate in the 8.2- to 10.3-GHz frequency range. The tuning bandwidth of both filters is 2.0 GHz. Typically, the midband insertion loss over the tuning band is 0 + or -dB; the 3-dB bandwidth is 29 + or - 11 MGz.

Varactor-tunable resonant filter elements that use the negative resistance of an FET to overcome the losses of the varactor and the circuitry were used to construct two three-section filters. One filter operates in the tunable frequency range from 8.4 to 9.2 GHz; a second filter, in the required 9. 1- to 9.6-GHz frequency range. Midband insertion loss is typically 0 dB; 3-dB bandwidth is 100 MHz.

This report describes the results of studies to increase the understanding of the requirements for successful glass passivation, by chemical vapor deposition (CVD), of metallized silicon planar integrated circuits (ICs) to improve both performance and reliability. The effects of various conditions for low-temperature (350 to 450 C) CVD of phosphosilicate glass (PSG) layers by oxidation of silane plus phosphine were correlated with the physical and chemical properties of deposited films. It is concluded that the important conditions to control are substrate temperature of deposition, oxygen-to-hydride ratio, hydride input, silane-to-phosphine ratio, and nitrogen input.

An investigation into the reliability of polycide conductors has been performed utilizing highspeed CMOS logic circuits (QMOS) and a parametric test circuit, the contact-resistance test vehicle (CRTV). The hermetically-packages QMOS units were split into control- and test-circuit groups; control circuits utilizing standard QMOS processing with n+ polysilicon gates, test circuits utilizing n+ polysilicon/TaSi2 (polycide) gates. Relevant features of the CRTV include long, narrow (2.5 micron to 3 micron) polycide lines connected to overlying Al or Al-1%Si Kelvin-contact patterns through small (1.5 micron x 1.5 micron to 2 micron x 2 micron) interlevel contacts, and large (600 micron x 600 micron) polycide/oxide/silicon capacitors, the (3000 A polysilicon/1600 A TaSi2) polycide being separated from the silicon substrate by an unpatterned, 500 A stream-grown gate oxide. No significant degradation in either CRTV polycide line integrity or CRTV gate-oxide breakdown strength was experienced during 30 cycles of thermal shock (-70 C to +100 C).

Dry and wet (pyrogenic steam)-grown thermal oxides on (100) silicon were made for an investigation of the radiation sensitivity of MOS devices. Oxides were grown under conditions known to produce state-of-the-art hardened oxides as well as very soft oxides. MOS capacitors were fabricated with thin semi-transparent and thick aluminum gates for irradiation with 10.2-eV vacuum ultraviolet (VUV) photons and 1-MeV electrons, respectively. Electrical measurements were made on MOS capacitors to determine trapped-charge density, charge transport, and thermal-trap depth, using high frequency and quasi-static CV, triangular voltage sweep (TVS), and thermally stimulated current (TSC) techniques. TSC measurements taken on irradiated capacitors to characterize the thermal-energy trap spectra gave varied results. Analytical measurements of interface stoichiometry and impurity profiles were done by the use of ion-scattering spectroscopy (ISS), x-ray photoelectron spectroscopy (XPS), and secondary-ion mass spectroscopy (SIMS).

The objective of this program is to develop a monolithic GaAs dual-gate FET phase shifter, operating over the 4- to 8-GHz frequency band and capable of a continuously programmable phase shift from 0 deg through N times 360 deg where N is an integer. The phase shift is to be controllable to within +3 deg. This phase shifter will be capable of delivering an output power up to 0 dBm with an input and output VSWR of less than 1.5:1. Progress 1. The photomask of a 0 to 90 deg monolithic GaAs dual-gate FET phase shifter has been procured, and we are in the process of fabricating the phase shifter. 2. We have designed and fabricated a 50 ohm, 4-line interdigitated coupler. Also, we have designed and fabricated a 25-ohm, 6-line interdigitated coupler. The performance of both couplers agrees quite well with the theoretical results. Technical Problems there was no major problem during this period.

Single mode fiber output power of over 7.5 mW cw has been obtained by the use of unique adjustable coupling modules that were developed for this program and that are being delivered to NRL. These are the highest powers ever reported coupled between diode lasers and single mode fibers. Coupling efficiencies over 25% were obtained in simple butt coupling by taking advantage of the large mode size available from RCA CDH LOC lasers. We also observed peak fiber power of over 9 mW with 100 ns 50% duty cycle pulses. The miniature models provide relative transverse and lateral motion between fiber and laser with 2000A resolution, allowing fine tuning against long term drifts. The coupling, while adjustable, is still stable against moderate acceleration of module and motion of fiber pigtail. The adjustments may be adapted to servo control. Still higher coupling efficiencies might be expected with cylinder lenses bonded to the fiber. Initial experiments indicated the need for further work to achieve accurate and stable attachment of lens to fiber.

A 256-element platinum silicide Schottky-barrier IR-CCD line sensor, developed under a prior contract, was fabricated to a matrix of processing variations and mask modification in an effort to improve the performance of the device. A new device, tC1258, resulted from the optimization study. This report details the wafer fabrication and packaging by wafer lot of all devices processed as an aid to the sponsor in evaluating the arrays. (Author)

The report describes the design and performance of FET power amplifier modules for quiet radar requirements. In the initial part of this program suitable device types capable of operation at the 9.5- to 10.5-GHz frequency band were studied. FET combiner circuits were developed to increase power performance of FET chips. Power modules were designed and tested for inclusion into a prototype power amplifier. Module requirements were 4-dB gain with 1.2-W output power. Results obtained from a typical combined FET module were a power output of 1.3 W with 4.5-dB gain. The final part of the program emphasized the construction of power modules for a conjoint power amplifier with 5-W output power. In all, seven, 1.2-W and two 0.5-W modules were built and incorporated into the final amplifier. The following results were obtained from the completed unit: 5-W power output with a gain of 29 + or 1 dB from 9.5 to 10.5 GHz. (Author)

The FET Frequency Discriminator is an experimental microwave frequency discriminator developed for use in a specialized set-on VCO frequency memory system. Additional development and evaluation work has been done during this program to more fully determine the applicability of the FET frequency discriminator as a low-cost, expendable receiver front-end for both surveillance and ECM systems. Various methods for adjusting the frequency-to-voltage characteristic of the discriminator as well as the effects of detector characteristics and ambient temperature changes were evaluated. A number of discriminators for use in the 7- to 11-GHz and the 11- to 18-GHz bands were fabricated and tested. Interim breadboard and final packaged models were either delivered or installed in developmental frequency systems. The major limitations and deficiencies of the FET frequency discriminator that were reviewed during the program include the effects of temperature, input power level variations, nonlinearity, and component repeatability. Additional effort will be required to advance the developmental status of the FET frequency discriminator to the level necessary for inclusion in low-cost receiver systems, but the basic simplicity of the approach continues to show much promise. (Author)

The objectives of the program are to: (1) investigate high-energy ion implantation of donors into GaAs for multigigabit-rate GaAs integrated-circuit (IC) development and (2) to study the use of high-power lasers and other techniques for removing lattice damage and activating implanted species. GaAs ICs require the selective definition of n-layers in semi-insulating (SI) GaAs for the fabrication of active devices such as FETs, TELDs, and Schottky-barrier diodes. In order to fabricate such device elements, a capability for realizing n-layers with doping ranging from 10 to the 16th power to 5 x 10 to the 18th power/cc and thicknesses from 1 to o.15 micrometer is required. Until the inception of this program, the major effort on ion implantation into GaAs has been at energies less than 500 keV, which limits the implant depth to typically less than several hundred nanometers. During this program, high-energy implantation of Si into SI GaAs at energies of 30 to 1200 keV has been investigated. Projected ranges and straggles have been measured by secondary ion-mass spectrometry (SIMS). Based on these measurements, we have produced up to approx. 1-micrometer-thick n-type GaAs layers at doping levels of approx. 5 x 10 to the 16th power to 1 x 10 to the 18th power/cc by multiple-energy Si implantation.

This report describes research undertaken to study and optimize the device properties of 1.3-micron InGaAsP edge-emitting LEDs fabricated by both vapor-phase epitaxy (VPE) and liquid-phase epitaxy (LPE). Edge-emitting LEDs have been prepared with both growth methods with a combination of properties rivaling the best reported to date. In the previous final report (RADC-TR-80-110) details of the VPE growth process were presented. Details of the LPE growth process are presented here. The LED efficiency of LPE devices was found to increase with decreasing cavity thickness. A value over 1% was measured with a 1000 lambda. Contact stripe width and coupling technique were also varied to achieve maximum power into an optical fiber. The best coupling was obtained with a 12-micron-wide contact stripe. Significantly better coupling was also achieved with a balled, rather than cleaved, end fiber. More than twice the power could be coupled into a 100-micron core diameter fiber, as compared to a 50-micron core fiber. The temperature dependence of LED emission was also measured for both VPE and LPE devices. LED efficiency dropped over 30% between 20 and 70 C, while an emission wavelength shift of 5 to 6 lambda/C was observed over the same temperature range.

Process development work for a hardened N+ polysilicon-gate CMOS/SOS process has demonstrated that it is possible to make functional 4K CMOS/SOS static RAMs that are hard to 5 x 10 to the 5th power rads without the implementation of special hardened circuit design techniques. Present circuit probe yields are low, limited by the lack of a hardened low-temperature contoured field oxide. Independent research has shown that a hardened reflow process is possible for such field oxides. Development of this reflow process is nearly complete and should result in significant improvement in yields when fully integrated into the rad-hard N+ process. (Author)

The objectives of this program are: (1) study of high-energy ion implantation of donors into GaAs for multigigabit-rate GaAs integrated-circuit development; and (2) annealing of implanted GaAs using high-power lasers to remove lattice damage and activate implanted donors. We have: (1) investigated implantation of Si(28+) into semi-insulating GaAs with implant energies ranging from 40 keV to 1.2 MeV; (2) developed a capless thermal annealing process under arsenic overpressure which results in high activation efficiency with excellent surface morphology; (3) investigated laser-annealing of Si-implanted GaAs using a high-power Nd:Glass laser and a ruby laser. Electrical activation of high-dose, low-energy (300 keV) implanted samples is many times higher in laser-annealed samples than for those thermally annealed; (4) demonstrated nonalloyed ohmic contacts formed by direct evaporation of AuGe onto high-dose implanted laser-irradiated GaAs surface; and (5) studied impurity distribution in as-implanted, thermally annealed, and laser-annealed samples by secondary ion mass spectrometry. The amount of impurity redistribution depends on the energy and the dose of implantation and on the energy density of the annealing laser pulse. Investigations were continued in (1) si-implantation and capless annealing; (2) laser and electron beam annealing; and (3) chromium redistribution in implanted and annealed GaAs.

This document is the sixth semiannual report and the final report of a basic study of the modes of injection lasers. The concern is the fundamental relationship between the modal properties of diode lasers, their structure, and the nature of the electrical drive. The semiannual report features three pioneering studies: The development of an equation of state relating the laser power, spectrum, and beam profile to the input current and laser structure; the behavior of the laser on transition of threshold as the current is increased through the immediate vicinity of threshold; and the comparison of the laser spectrum under pulsed drive to excitation with a dc current. It also touches on the behavior of quarternary lasers operating at 1.2 micrometers. The report concludes with a consideration of the outstanding fundamental problem at the present time, the dynamic interaction of the laser which reduces the number of spectral lines in the coherent output of a laser as the current drive is increased.

Various approaches to passivating the surface of GaAs have been explored. All of these were aimed at tying dangling bonds with atoms bonding more tightly than either Ga or As. Atomic species of hydrogen and nitrogen were generated by a glow discharge in H2, NH3, or N2. Nitridization with ammonia appears most promising. The degree of passivation was monitored by photoluminescence. A fourfold improvement in luminescence efficiency was obtained with nitridization while a factor-of-ten improvement can be obtained with the less practical technique of generating an (AlGa)As skin. (Author)

Corrosion of thin-film aluminum and gold under defect-containing passivation layers of phosphorus-doped SiO2 and plasma-deposited silicon nitride was investigated. Metal test patterns with corresponding passivation patterns, including deliberate passivation defects, made it possible to measure both corrosion current and corrosion rate. Measurements were done as a function of relative humidity and temperature. Electrochemical bias techniques were used to determine the relative corrosion stabilities of various metallized substrates. Fluoride and chloride contaminants produced greatly accelerated corrosion reactions for aluminized films. Alloying aluminum films improved their corrosion stability. The H2 in the forming gas ambient during alloying further improved the corrosion stability. Measurements of film stress versus corrosion stability did not correlate well. However, films under compressive stress may exhibit an improved corrosion stability. Fluorescent pH indicators were tested as a method of decorating IC devices. On aluminized IC devices in the presence of bias, some indicators exhibited fluorescence at localized sites. The effect on corrosion current of various surface treatments such as heating, etching, storage, and surface chemical modification were examined. Application of hexamethyldisilazane reduced surface currents by a factor varying from 100X to 1000X. (Author)

Both VPE and LPE InGaAsP/InP edge- and surface-emitting LEDs have been fabricated and tested under the present contract. Table 1 contains a summary of the results. Although the surface emitter provides greater total power, its halfwidth is considerably larger than that of the edge emitter. This increases pulse dispersion and reduces the amount of power that can be coupled into an optical fiber. The experimental conditions for the vapor-phase growth of InGaAsP and InP alloy are described. Detailed growth procedures are specified and plots of alloy composition, bandgap, lattice parameter and doping levels vs growth parameters are included. Modulation rates close to 100 MHz have been measured for 1.27-micron edge-emitting LEDs. Fall times on the order of 10 ns for (90 to 10% response) also have been obtained. Over fifty edge-emitting VPE 1.27-micron heterojunction LEDs have been fabricated from numerous wafers. External power efficiencies equal to or greater than 0.3% were routinely measured, with maximum efficiencies on the order of 0.7% (from one edge). Wafer-to-wafer reproducibility of power efficiencies has now been demonstrated with both the LPE and VPE growth techniques.

Phase I of this study proved the feasibility of the variable-gain, constant-output power amplifier from the chosen approach by demonstrating a breadboard model. During Phase II, the development of the final packaged amplifier with improved performance, the following tasks were completed: (1) a dual-gate FET amplifier was redesigned to obtain more gain (10 dB) over the band; (2) a video amplifier was designed and developed for higher gain (40 dB); and (3) circulators were eliminated to reduce the size of the amplifier. This amplifier was demonstrated to operate over a 3-GHz band (4.5 to 7.5 GHz) and to provide an output power of 3 + or - 2 dBm over its entire dynamic range of -45 to 0 dBm of input power. The linear ACG amplifier developed under this program has the following key features. (1) It preserves amplitude modulation of the incoming signal. (2) It can perform normal AGC function under a multiple-pulse condition. This characteristic may prove to be very useful for handling multiple threats. (3) It is very versatile. It can provide separate ports to facilitate output power level adjustment and input signal detection and monitoring. (4) It has very fast response. The rise time and fall time of this amplifier are better than 15 ns which is limited by the measurement system., Includes Rept. no. PRRL-79-CR-46.

This program was aimed at the study of epitaxial growth of high- resistivity GaAs, high-energy implantation of donors into GaAs, and the use of high-power lasers for annealing implanted GaAs layers. We have made significant progress in these three areas. We have grown high-resistivity Cr-doped GaAs layers with good surface morphology using both Ga/Hcl/AsH3/H2 and Ga/AsCl3/H2 processes. n-Layers grown on epitaxial buffer layers have consistently shown lower compensation than direct growth on SI GaAs substrates. Cr doped layers have been grown on both SI GaAs and n + or - GaAs substrates. Ion implantation into epitaxial buffer layers, in general, leads to higher electron mobility than direct implantation.

This report describes a study of techniques for improving the performance of CCDs in a nuclear radiation environment. A test chip with both n-surface- and n-buried-channel devices (128-stage four-phase registers) utilizing a double-polysilicon overlapping gate structure was designed, fabricated with low-temperature, pyrogenically-grown channel oxides, and tested. The chip also contains threshold tracking circuits designed to automatically correct for threshold shifts induced by ionizing radiation as well as automatic input and output biasing circuits to provide a radiation-hardened means of injecting and detecting CCD signals. The devices were subjected to high energy (1 MeV) electron radiation and the optimum circuit techniques to improve the radiation tolerance of CCDs were determined. (Author)

The objectives of this research program are to develop planar GaAs transferred-electron logic devices (TELDs), and to fabricate and evaluate a monolithic full ADDER. The TELD-FET (Field Effect Transistors) combination device provides substantial improvements in operating characteristics over TELD with resistive loads. It has better trigger-sensitivity and stability. The power dissipation can also be reduced to 0.16 to 0.2 of that for TELDs with resistive load. The capacitive output of TELD-FET makes direct interconnections possible without level shifting. Majority logic can be implemented with TELDs which reduces the component count substantially. The full ADDER circuit is a good example of this. Discrete test FET and TELD dc characteristics were evaluated on the curve tracer. FET characteristics were in close agreement with the design goals, but TELDs did not show any substantial current drop. A maximum current drop measured was 10 to 15%, and the design goals are 25 to 35%. Technology was developed for the fabrication of small-scale GaAs integrated circuits. Further improvements are required in the growth of GaAs epitaxial layers which will result in improved device characteristics. The 25 to 30% current drop devices are required for the successful operation of TELD integrated digital circuits.

The program objectives are: study of high-energy (about 1 MeV) ion implantation of donors into GaAs for multigigabit-rate integrated-circuit development and annealing of implanted GaAs using high-power lasers to remove lattice damage and activate implanted donors. Results obtained are: We have investigated implantation of 28Si(+) into semi-insulating GaAs with implant energies ranging from 40 keV to 1.2 MeV; we have analyzed the profiles and range statistics of 28Si-implanted GaAs with energies of up to 1.2 MeV using (Secondary Ion-Mass Spectroscopy) SIMS; we have investigated laser-annealing of high-dose Si-implanted GaAs using both a high-power Nd:glass laser and a ruby laser; optical absorption in Si-implanted GaAs wafers irradiated with high-power Nd:glass laser pulses has been studied; impurity distribution in as-implanted, thermally annealed, and laser-annealed samples has been investigated by SIMS; and investigation of 28Si(+) implantations in GaAs at the low-implant energy (300 keV) shows that the electron concentration attained has an upper limit at the high-dose region and a lower limit at the low-dose region following thermal annealing.

The effort on this program was aimed at fabricating a low-voltage, high-speed VCO to cover the 11- to 18-GHz frequency range for use in a set-on VCO-type of frequency memory in place of an arrangement requiring three VCOs and a multiplexer. The most important accomplishments were: (1) The development of a low-power VCO covering the 11- to 18-GHz range using a GaAs hyperabrupt junction varactor diode and requiring a very small tuning voltage requirement; (2) The fabrication of a new type of frequency discriminator which uses the roll-off characteristic of a microwave FET; (3) Measurements leading to an understanding of the behavior of GaAs hyperabrupt varactors at high input levels. GaAs hyperabrupt varactors were produced having capacitance ratios in excess of 10:1, but less than the expected frequency tuning ranges were orginally obtained from VCOs with these hyperabrupt varactors used as the tuning diode. Special network analyzer measurements with varying levels of input drive power showed the impedance of the hyperabrupt varactors to be unusually sensitive to the incident power level resulting in a significant reduction in maximum capacitant at levels consistent with those to which the varactors are exposed in the oscillator.

The objectives of this program are to (1) develop techniques for the epitaxial growth of high-resistivity buffer layers on semi-insulating (SI) GaAs substrates, (2) investigate ion implantation of donors into GaAs over a range of 50 to 2000 keV, and (3) investigate the potential of laser annealing to remove lattice damage caused by ion implantation and to activate the implanted donors. Preliminary results on growth of Cr-doped buffer layers by vapor-phase epitaxy (VPE) were described in our previous report. These Cr-doped layers were grown using the Ga/HC1/AsH3/H2 system. Based on these results specifications for a new semi-automatic gas-handling system were developed and the unit purchased from Crystal Specialties.

This program was directed at fabricating infrared focal planes consisting of Schottky-barrier detectors multiplexed by charge-coupled shift registers, and demonstrating their imaging capability against 300K background radiation. Three devices were designed and fabricated: a 64-bit, three-phase line-array with transfer gaps, a 62-bit line array, and a 25x50 area array, the latter two with four-phase, sealed-channel, overlapping-gate, double-polysilicon structure. The detectors were palladium silicide and platinum silicide on p- silicon. Fabrication involved only standard silicon-processing operations. Excellent agreement has been obtained between calculated infrared performance and experimental data. Detector uniformity better than 1%, already achieved with palladium silicide, is adequate for staring-mode thermal imagers. These sensors make possible imagers with thermal resolution on the order of tenths of a degree C, and production costs less than present scanned systems., Sponsored in part by DARPA.

A program is under way to fabricate infrared-sensitive, charge- coupled imagers with Schottky-barrier detectors. The previous work has been with three-phase, single metallization line arrays using palladium-silicide, Schottky-barrier detectors. The present effort is directed at fabrication of a 25 x 50 area array. The design of the 25 x 50 area array is nearly complete, and masks will soon be ordered. Arrays of this design will be made with both Pd2Si and PtSi Schottky barriers. There will be optional masks for guard rings and for buried-channel operation. Processing has begun on a batch of wafers with Pt. Optical absorption measurements revealed a possible problem in the processing procedure, and an appropriate change was made. Infrared calculations were made demonstrating that thermal imaging with PtSi is possible, but that excess dark current at the detectors must be avoided., See also report dated 14 Nov 1975, ADA025224.

In this report we discuss some of the experimental measurements made on passive directional couplers. These measurements are designed to help check the accuracy of the processing used in formation of these devices and indicate a large degree of uncertainty in dimensions caused by both the process used in forming the Nb patterns, and in subsequent diffusion of these patterns., Sponsored in part by DARPA.

The ultimate goal of this work is the fabrication of a two- dimensional infrared imager. The authors previous work with the 64 x 1 line array has proven the feasibility of the Schottky-barrier detector silicon/CCD system, and has, in the vidicon mode, demonstrated a uniformity approaching that needed for thermal imaging. In the present work, the two-dimensional imager is being designed and fabricated. The first arrays will again have palladium- silicide on p-silicon as the detector system, but subsequent arrays will be made with platinum-silicide for deeper IR response. A line array is also included on the chip to provide additional features. The considerations that have gone into the design are discussed below. Quantitative infrared measurements have already begun and have yielded good agreement with previous measurements on the absolute quantum efficiency of PdSi:p-Si detectors., See also report dated 15 May 1975, ADA018057.

Heterojunction laser diodes of GaAs and (A1Ga)As have become increasingly sophisticated structures fabricated by liquid-phase epitaxy (LPE). Because of progress made both in the technology and in our theoretical understanding of laser diodes, it is now possible to design devices for specific applications. There is general interest in devices both for high peak power (pulsed) operation at room temperature and in diodes capable of reliable continuous room-temperature operation. Both types of devices require low thermal and electrical resistance but other requirements differ. The high-power pulsed lasers need not have very low threshold current densities, but they must be capable of withstanding catastrophic degradation resulting from excessive optical flux density at the emitting facet. The cw lasers, on the other hand, operate at low power levels (tens of milliwatts) and require low threshold current densities to minimize thermal dissipation problems. The beam divergence should be as low as possible in all devices to reduce the size of the external optical collimating system. In this final report, we discuss techniques used to achieve the control of material parameters of state-of-the-art high-power laser diodes with particular emphasis on the question of radiation pattern control.

The processing of the monolithic dual-gate FET phase shifter has been completed, and the rf testing is in progress. The new design of the 360 deg phase shifter has been conceived requiring fewer hybrids. The mask design is in progress.

The objective of this program was the study and development of directional coupler modulators based on the use of the LiNb(x)Ta(1-x)O3 waveguide system developed at RCA Laboratories. In this final report, observations of surface diffusion and ridge formation are described. Briefly, the surface of the LNT guide is raised by an amount equal to approximately twice the initial niobium thickness. The lateral spread of Nb in y-plates is approximately 20 times the diffusion depth while the spread in x-plates appears to be less than the resolving power of the measurements. The effect of this spread on the operation of stripe guides is discussed and experimental observations on stripe guides and stripe couplers are described. A summary is given of how directional coupling modulators are expected to operate. The effect that constructional tolerances have on the quality of switching that may be obtained in actual devices is analyzed., Sponsored in part by DARPA.

During this quarter, testing of a new braking and stopping method for the high speed carriage return was continued. Wiring of the character generator has been completed. A method of mounting has been worked out that will have the circuits more easily accessible for servicing. The converter has been modified to accept parallel signals from punched paper tape. The circuits have been designed and their construction is 50% completed. (Author)

The basic limits of vision and image detection are discussed. Experimental results with the direct view intensifier are reported. A general discussion of pickup tube limitations concludes that the image intensifier orthicon is a very suitable pickup tube for a brightness intensifier amplifying a low light scene. Other intensifications methods and storage operation of intensifier orthicons are also investigated and discussed. The use of the image intensifier orthicon for optical pulse ranging is suggested.

The report concentrates primarily upon the systems BaClF:Ln2+ and ABF3:Ln2+ (where A = alkali-metal ion, and B = alkaline-earth ion), those compounds selected as best suited to our objectives. The problems were in three major categories: reduction of the rare earth from the normal trivalent to divalent, incorporation of the desired ion into the host with retention of the desired valence state, and the growth of single crystals of suitable optical quality. The first and third categories were satisfactorily solved in many cases, while the second was solved only to a limited extent. On the basis of these studies, one can specify in some detail the materials in which, and the conditions under which, this second aspect of the problem can be successfully solved., Report on Applied Research in Electronic and Magnetic Materials.

This report is an enumeration of the 2470 self-dual eight-argument positive canonical threshold functions, each specified by its Chow parameters, each listed with its minimal 1-realization, and each accompanied by statistics on the number of extremals and iterations involved in its solution, together with a coded indication of its symmetry. The table is ordered lexicographically by the Chow parameters to facilitate test-synthesis by table look-up.

A series of extremely homogeneous Si-Ge solid solution alloys were prepared by the horizontal zone-melting technique. The materials of various compositions were used to make accurate deter minations of density, lattice parameter, phase equilibria, and band gap as functions of composi tion. The densities of about 100 samples were determined to an accuracy of =0.1% by the method of Archimedes. The solidus temperatures were determined at intervals of 5-10%Si by the DTA method, and the results confirm the original (1939) phase diagram of Stohr and Klemm.

The report describes research performed during a two-year period in order to develop a semiconductor cold-cathode electron emitter with emission properties suitable for practical applications. Greatly improved cold-cathode structures based on negative electron affinity surfaces and on GaAs-(AlGa)As heterojunction structures grown by liquid phase epitaxy were developed. The key to the successful development of this device was the ability to obtain highly doped p-type GaAs with electron-diffusion lengths as high as about 5 to 7 micrometers and a technique for the confinement of the carrier flow to the desired emitting area. Extensive studies on dc operation and cathode life were conducted under continuously pumped vacuum conditions as well as in sealed tubes, and operation was obtained for a period of 360 hr., See also Semi-annual rept. no. 3, AD750611.

Evidence is presented to show that the dominant current control mechanism in the insulated-gate cadmium sulfide thin film transistor (TFT) is conductivity modulation in the semiconductor by field effect action of the gate. The characteristics of the coplanar-electrode TFT having overlying ''ohmic'' contacts were demonstrated to be equivalent to the earlier staggered-electrode structure having underlying gold contacts. The measured drift mobility as calculated from the ratio of transconductance to input capacitance may be either higher or lower than the measured Hall mobility depending upon the method of preparation of the semiconductor film. An increase in the Hall mobility as a function of positive gate bias was found, contrary to predictions based upon the effect of scattering at the surface of a homogeneous semiconductor. Tests on various processing procedures and electrode contacts were carried out for cadmium sulfide and other materials potentially useful for TFT fabrication.