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At least 109 records · Page 6

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NASA NTRS1976

Evaluation of advanced microelectronic fluxless solder-bump contacts for hybrid microcircuits

Technology for interconnecting monolithic integrated circuit chips with other components is investigated. The advantages and disadvantages of the current flip-chip approach as compared to other interconnection methods are outlined. A fluxless solder-bump contact technology is evaluated. Multiple solder-bump contacts were formed on silicon integrated circuit chips. The solder-bumps, comprised of a rigid nickel under layer and a compliant solder overlayer, were electroformed onto gold device pads with the aid of thick dry film photomasks. Different solder alloys and the use of conductive epoxy for bonding were explored. Fluxless solder-bump bond quality and reliability were evaluated by measuring the effects of centrifuge, thermal cycling, and high temperature storage on bond visual characteristics, bond electrical continuity, and bond shear tests. The applicability and suitability of this technology for hybrid microelectronic packaging is discussed.

Mandal, R. P.↗

NASA NTRS1982

Phase control and beam steering of semiconductor laser arrays

The operational principles and a possible device configuration of one dimensional monolithically integrated semiconductor laser arrays are described. The output beam of the array can be electronically steered. Devices of the type can find applications in optical communication systems where the power levels needed are above the capability of a single laser device.

Katz, J.↗

NASA NTRS1983

Semiconductor optoelectronic devices for free-space optical communications

The properties of individual injection lasers are reviewed, and devices of greater complexity are described. These either include or are relevant to monolithic integration configurations of the lasers with their electronic driving circuitry, power combining methods of semiconductor lasers, and electronic methods of steering the radiation patterns of semiconductor lasers and laser arrays. The potential of AlGaAs laser technology for free-space optical communications systems is demonstrated. These solid-state components, which can generate and modulate light, combine the power of a number of sources and perform at least part of the beam pointing functions. Methods are proposed for overcoming the main drawback of semiconductor lasers, that is, their inability to emit the needed amount of optical power in a single-mode operation.

Katz, J.↗

NASA NTRS1984

LEC GaAs for integrated circuit applications

Recent developments in liquid encapsulated Czochralski techniques for the growth of semiinsulating GaAs for integrated circuit applications have resulted in significant improvements in the quality and quantity of GaAs material suitable for device processing. The emergence of high performance GaAs integrated circuit technologies has accelerated the demand for high quality, large diameter semiinsulating GaAs substrates. The new device technologies, including digital integrated circuits, monolithic microwave integrated circuits and charge coupled devices have largely adopted direct ion implantation for the formation of doped layers. Ion implantation lends itself to good uniformity and reproducibility, high yield and low cost; however, this technique also places stringent demands on the quality of the semiinsulating GaAs substrates. Although significant progress was made in developing a viable planar ion implantation technology, the variability and poor quality of GaAs substrates have hindered progress in process development.

Kirkpatrick, C. G.↗

NASA NTRS1985

Large-area thin-film modules

The low cost potential of thin film solar cells can only be fully realized if large area modules can be made economically with good production yields. This paper deals with two of the critical challenges. A scheme is presented which allows the simple, economical realization of the long recognized, preferred module structure of monolithic integration. Another scheme reduces the impact of shorting defects and, as a result, increases the production yields. Analytical results demonstrating the utilization and advantages of such schemes are discussed.

Tyan, Y. S.↗

NASA NTRS1986

MMIC devices for active phased array antennas

The use of finlines for microwave monolithic integrated circuit application in the 20 to 40 GHz frequency range. Other wave guiding structures, are also examined from a comparative point of view and some sonclusions are drawn on the basis of the results.

Mittra, R.↗

NASA NTRS1987

Optically controlled microwave devices and circuits: Emerging applications in space communications systems

Optical control of microwave devices and circuits by an optical fiber has the potential to simplify signal distribution networks in high frequency communications systems. The optical response of two terminal and three terminal (GaAs MESFET, HEMT, PBT) microwave devices are compared and several schemes for controlling such devices by modulated optical signals examined. Monolithic integration of optical and microwave functions on a single semiconductor substrate is considered to provide low power, low loss, and reliable digital and analog optical links for signal distribution.

Bhasin, Kul B.↗

NASA NTRS1987

Detection of radio-frequency modulated optical signals by two and three terminal microwave devices

An interdigitated photoconductor (two terminal device) on GaAlAs/GaAs heterostructure was fabricated and tested by an electro-optical sampling technique. Further, the photoresponse of GaAlAs/GaAs HEMT (three terminal device) was obtained by illuminating the device with an optical signal modulated up to 8 GHz. Gain-bandwidth product, response time, and noise properties of photoconductor and HEMT devices were obtained. Monolithic integration of these photodetectors with GaAs microwave devices for optically controlled phased array antenna applications is discussed.

Bhasin, K. B.↗

NASA NTRS1986

A 30-GHz monolithic receiver

Several monolithic integrated circuits have been developed to make a 30-GHz receiver. The receiver components include a low-noise amplifier (LNA), an IF amplifier, a mixer, and a phase shifter. The LNA has a 7-dB noise figure with over 17 dB of associated gain. The IF amplifier has a 13-dB gain with a 30-dB control range. The mixer has a conversion loss of 10.5 dB. The phase shifter has a 180-deg phase shift control and a minimum insertion loss of 1.6 dB.

Liu, Louis C. T.↗

NASA NTRS1986

Phase-locked arrays of semiconductor injection lasers - A review

Arrays of phase-locked semiconductor injection lasers integrated monolithically on the same substrate are one potential method for obtaining higher power levels (in controlled mode operation) than those available from a single laser. This paper describes basic methods for analyzing the electrical and optical characteristics of these devices, and discusses problems associated with maintaining a stable operation in a single array mode ('supermode'). Various experimental results are presented and compared with theory.

Katz, Joseph↗

NASA NTRS1988

Optically interconnected phased arrays

Phased-array antennas are required for many future NASA missions. They will provide agile electronic beam forming for communications and tracking in the range of 1 to 100 GHz. Such phased arrays are expected to use several hundred GaAs monolithic integrated circuits (MMICs) as transmitting and receiving elements. However, the interconnections of these elements by conventional coaxial cables and waveguides add weight, reduce flexibility, and increase electrical interference. Alternative interconnections based on optical fibers, optical processing, and holography are under evaluation as possible solutions. In this paper, the current status of these techniques is described. Since high-frequency optical components such as photodetectors, lasers, and modulators are key elements in these interconnections, their performance and limitations are discussed.

Bhasin, Kul B.↗

NASA NTRS1988

Grid oscillators

Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

Popovic, Zorana B.↗

NASA NTRS1987

Detection of radio-frequency modulated optical signals by two and three terminal microwave devices

Bhasin, K. B.↗

NASA NTRS1989

Composite Semiconductor Substrates

Epitaxial structure of three semiconductor materials - silicon, gallium arsenide, and cadmium telluride - makes possible integrated monolithic focal-plane arrays of photodectors. Silicon layer contains charge-coupled devices, gallium arsenide layer contains other fast electronic circuitry, and cadmium telluride layer serves as base for array of mercury cadmium telluride infrared sensors. Technique effectively combines two well-established techniques; metalorganic chemical-vapor deposition (MOCVD) and molecular-beam epitaxy (MBE). Multilayer structure includes HgCdTe light sensors with Si readout devices and GaAs signal-processing circuits. CdTe layer provides base for building up HgCdTe layer.

Nouhi, Akbar↗

NASA NTRS1988

Surface emitting lasers for optical circuitry - Optical interconnect technology

Surface emitting (SE) lasers and their application in VLSI optical interconnect networks are considered. In particular, the advantages provided by SE lasers in optical interconnect circuits and monolithic integration are discussed. Some of the requirements, such as wavelength stability, power dissipation, emission angle, size, etc., are compared with respect to conventional laser diodes. It is noted that the operation of SE lasers will be critically dependent on the properties of the feedback reflectors. Experimental measurements of reflection spectra on AlGaAs/GaAs multilayer reflectors and InAlAs/InGaAs etalons formed with molecular beam epitaxy (MBE) are presented.

Yu, P. K. L.↗

NASA NTRS1988

Monolithic watt-level millimeter-wave diode-grid frequency tripler array

In order to provide watt-level CW output power throughout the millimeter and submillimeter wave region, thousands of solid-state diodes have been monolithically integrated using a metal grid to produce a highly efficient frequency multiplier. Devices considered include GaAs Schottky diodes, thin MOS diodes, and GaAs Barrier-Intrinsic-N(+)diodes. The performance of the present compact low-cost device has been theoretically and experimentally validated.

Hwu, R. J.↗

NASA NTRS1988

Optically interconnected phased arrays

Bhasin, Kul B.↗

NASA NTRS1990

GTO/FET Cascode Three-Terminal Switch

Neither external bias nor energy-storage components required. Three-terminal semiconductor switching circuit features high switching speed, extremely high turnoff safe operating area (area in current-vs-voltage plane), moderately low forward ("on"-state) voltage drop, and efficient utilization of silicon in design of components. Includes gate-turn-off thyristor (GTO) and low-voltage (low-on-resistance) field-effect transistor (FET-1) connected in series to form cascode pair. Made of commercially available, discrete components, as hybrid circuit package or as monolithic integrated circuit.

Rippel, Wally E.↗