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Surprising patterns of CMOS susceptibility to ESD and implications on long-term reliability

Description: CMOS electrostatic discharge (ESD) failures in a product where, by design, the device input terminals are not accessible to ESD led to this study of device susceptibility and an analysis of the long-term reliability of devices in assemblies from that production line. Some surprising patterns of device susceptibility are established and it is shown that the probability of long-term failure in devices whose electrical characteristics have been degraded by electrostatic discharge is small.
Date: January 1, 1980
Creator: Schwank, J.R.; Baker, R.P. & Armendariz, M.G.
Partner: UNT Libraries Government Documents Department

SEM technique for experimentally locating latch-up paths in integrated circuits

Description: A technique is presented for using the scanning electron microscope (SEM) in the electron-beam-induced current (EBIC) mode to delineate latch-up paths in CMOS ICs. In the EBIC mode, the current produced by the collection and separation of the electron-beam-generated electron-hole pairs in the space charge regions of the device is measured and used to form an image. Since the collection of these carriers is dependent on space charge region width (and thus junction potential), anything that alters the depletion layer width will affect the collection efficiency. In a latch condition the junctions involved in the latch will be biased differently from those which are not, and thus the EBIC signal from those regions should be measurably different.
Date: January 1, 1980
Creator: Dressendorfer, P. V. & Armendariz, M. G.
Partner: UNT Libraries Government Documents Department

Advanced packaging technology for high frequency photonic applications

Description: An advanced packaging concept has been developed for optical devices. This concept allows multiple fibers to be coupled to photonic integrated circuits, with no fiber penetration of the package walls. The principles used to accomplish this concept involves a second-order grating to couple light in or out of the photonic circuit, and a binary optic lens which receives this light and focuses it into a single-mode optical fiber. Design, fabrication and electrical/optical measurements of this packaging concept are described.
Date: March 1, 1996
Creator: Armendariz, M.G.; Hadley, G.R. & Warren, M.E.
Partner: UNT Libraries Government Documents Department

Unlimited-bandwidth distributed optical phase modulators and detectors: Design and fabrication issues

Description: Practical and theoretical limits on the bandwidth of distributed optical phase modulators and traveling-wave photodetectors are given. For the case of perfect velocity matching, RF transmission losses are the main performance-limiting factor. However, some high-performance modulators require highly-capacitive transmission lines making proper slow-wave operation difficult to achieve.
Date: August 1, 1994
Creator: Vawter, G. A.; Hietala, V. M.; Kravitz, S. H. & Armendariz, M. G.
Partner: UNT Libraries Government Documents Department

CLASP (Capture and Locking alignment Spring Positioner): A micromachined fiber auto-positioning device

Description: This work provides a method of mechanical alignment of an array of single mode fibers to an array of optical devices. The technique uses a micromachined metal spring, which captures a vertical, pre- positioned fiber, moves it into accurate alignment, and holds it for attachment. The spring is fabricated from electroplated mickel, using photodefined polyimide as a plating mask. The nickel is plated about 80 {mu}m thick, so that a large fiber depth is captured. In one application, the nickel springs can be aligned to optics on the back side of the substrate. This entire concept is referred to as CLASP (Capture and Locking Alignment Spring Positioner). These springs can be used for general alignment and capture of any fiber to any optical input or output device. Passive alignment of fiber arrays to {plus}/{minus} 2{mu}m accuracy has been demonstrated, with a clear path to improved accuracy.
Date: March 1, 1996
Creator: Kravitz, S. H.; Word, J. C.; Bauer, T. M.; Seigal, P. K. & Armendariz, M. G.
Partner: UNT Libraries Government Documents Department

Velocity matched electrode structures on doped semiconductors for large bandwidth optoelectronic modulators

Description: High-speed optoelectronic modulators are becoming increasingly important in microwave applications. These devices are necessarily electrically large and hence require velocity matching of the microwave signal to the light. A design methodology for velocity matched electrodes on doped semiconductor devices will be presented. As an example of a successful device design, experimental results on a >10 bandwidth high-efficiency (>15{degrees}/V/mm) Mach Zehnder interferometer will be presented.
Date: December 1995
Creator: Hietala, V. M.; Vawter, G. A.; Fuchs, B.; Armendariz, M. G. & Sullivan, C. T.
Partner: UNT Libraries Government Documents Department

Electrical characterization and application of very high speed vertical cavity surface emitting lasers (VCSELs)

Description: Vertical Cavity Surface Emitting Lasers (VCSELs) offer many benefits over conventional edge-emitting lasers including economical microelectronic batch processing, easy extension to 2-D arrays, and of interest here, very large intrinsic bandwidths due to reduced cavity volume. Results of electrical characterization of a 19 GHz bandwidth 850 nm VCSEL are presented. Small-signal characterization and modeling of the frequency response and device impedance is presented. Large signal performance is studied using two-tone RF and high-speed digital measurements. Appropriate drive conditions for high-speed digital applications are demonstrated.
Date: April 1, 1997
Creator: Hietala, V. M.; Lear, K. L. & Armendariz, M. G.
Partner: UNT Libraries Government Documents Department

Fabrication, Packaging, and Performance of VCSELs and Photodetectors for Space Applications

Description: Optocouplers are used for a variety of applications aboard spacecraft including electrical isolation, switching and power transfer. Commercially available light emitting diode (LED)-based optocouplers have experienced severe degradation of light output due to extensive displacement damage occurring in the semiconductor lattice caused by energetic proton bombardment. A new optocoupler has been designed and fabricated which utilizes vertical cavity surface emitting laser (VCSEL) and resonant cavity photodetector (RCPD) technologies for the optocoupler emitter and detector, respectively. Linear arrays of selectively oxidized GaAs/AlGaAs VCSELS and RCPDS, each designed to operate at a wavelength of 850nm, were fabricated using an airbridge contacting scheme. The airbridged contacts were designed to improve packaging yields and device reliability by eliminating the use of a polyimide planarizing layer which provided poor adhesion to the bond pad metallization. Details of the airbridged optocoupler fabrication process are reported. Discrete VCSEL and RCPD devices were characterized at temperatures between {minus}100 to 100 C. Devices were packaged in a face-to-face configuration to form a single channel optocoupler and its performance was evaluated under conditions of high-energy proton bombardment.
Date: March 9, 1999
Creator: Armendariz, M.G.; Briggs, R.D.; Choquette, K.D.; Geib, K.M. & Serkland, D.K.
Partner: UNT Libraries Government Documents Department

Metallization and packaging of compound semiconductor devices at Sandia National Laboratories

Description: Recent advances in compound semiconductor technology utilize a variety of metal thin films fabricated by thermal and electron-beam evaporation, and electroplating. An overview of metal processes used by Sandia`s Compound Semiconductor Research Laboratory is presented. Descriptions of electrical n-type and p-type ohmic contact alloys, interconnect metal, and metal layers specifically included for packaging requirements are addressed. Several illustrations of devices incorporating gold plated air bridges are included. ``Back-end`` processes such as flip-chip under bump metallurgy with fluxless solder reflow and plated solder processes are mentioned as current research areas.
Date: November 1, 1996
Creator: Seigal, P.K.; Armendariz, M.G.; Rieger, D.J.; Lear, K.L. & Sullivan, C.T.
Partner: UNT Libraries Government Documents Department

High-performance GaAs/AlGaAs optical phase modulators for microwave photonic integrated circuits

Description: A high-performance high-speed optical phase modulator for photonic integrated circuit (PIC) use is described. Integration of these optical phase modulators into a real system (compass) is also discussed. The optical phase modulators are based on depletion-edge translation and have experimentally provided optical phase shifts in excess of 60{degrees}/V{center_dot}mm with approximately 4 dB/cm loss while simultaneously demonstrating bandwidths in excess of 10 GHz.
Date: March 1, 1994
Creator: Hietala, V. M.; Kravitz, S. H.; Armendariz, M. G.; Vawter, G. A. & Carson, R. F.
Partner: UNT Libraries Government Documents Department

Proton Irradiation Effects in Oxide-Confined Vertical Cavity Surface Emitting Laser (VCSEL) Diodes

Description: Recent space experience has shown that the use of commercial optocouplers can be problematic in spacecraft, such as TOPEX/Poseidon, that must operate in significant radiation environments. Radiation--induced failures of these devices have been observed in space and have been further documented at similar radiation doses in the laboratory. The ubiquitous use of optocouplers in spacecraft systems for a variety of applications, such as electrical isolation, switching and power transfer, is indicative of the need for optocouplers that can withstand the space radiation environment. In addition, the distributed nature of their use implies that it is not particularly desirable to shield optocouplers for use in radiation environments. Thus, it will be important for the space community to have access to radiation hardened/tolerant optocouplers. For many microelectronic and photonic devices, it is difficult to achieve radiation hardness without sacrificing performance. However, in the case of optocouplers, one should be able to achieve both superior radiation hardness and performance for such characteristics as switching speed, current transfer ratio (CTR), minimum power usage and array power transfer, if standard light emitting diodes (LEDs), such as those in the commercial optocouplers mentioned above, are avoided, and VCSELs are employed as the emitter portion of the optocoupler. The physical configuration of VCSELs allows one to achieve parallel use of an array of devices and construct a multichannel optocoupler in the standard fashion with the emitters and detectors looking at each other. In addition, detectors similar in structure to the VCSELs can be fabricated which allows bidirectional functionality of the optocoupler. Recent discussions suggest that VCSELs will enjoy widespread applications in the telecommunications and data transfer fields.
Date: March 11, 1999
Creator: Armendariz, M.G.; Barnes, C.E.; Choquette, K.D.; Guertin, S.; Hash, G.L.; Schwank, J.R. et al.
Partner: UNT Libraries Government Documents Department

High-speed modulation of vertical cavity surface emitting lasers

Description: This report summarizes work on the development of high-speed vertical cavity surface emitting lasers (VCSELs) for multi-gigabit per second optical data communications applications (LDRD case number 3506.010). The program resulted in VCSELs that operate with an electrical bandwidth of 20 GHz along with a simultaneous conversion efficiency (DC to light) of about 20%. To achieve the large electrical bandwidth, conventional VCSELs were appropriately modified to reduce electrical parasitics and adapted for microwave probing for high-speed operation.
Date: March 1, 1998
Creator: Hietala, V.M.; Armendariz, M.G.; Choquette, K.D. & Lear, K.L.
Partner: UNT Libraries Government Documents Department

Ultra-high-speed optical and electronic distributed devices

Description: This report summarizes work on the development of ultra-high-speed semiconductor optical and electronic devices. High-speed operation is achieved by velocity matching the input stimulus to the output signal along the device`s length. Electronic devices such as field-effect transistors (FET`s), should experience significant speed increases by velocity matching the electrical input and output signals along the device. Likewise, optical devices, which are typically large, can obtain significant bandwidths by velocity matching the light being generated, detected or modulated with the electrical signal on the device`s electrodes. The devices discussed in this report utilize truly distributed electrical design based on slow-wave propagation to achieve velocity matching.
Date: August 1, 1995
Creator: Hietala, V.M.; Plut, T.A.; Kravitz, S.H.; Vawter, G.A.; Wendt, J.R. & Armendariz, M.G.
Partner: UNT Libraries Government Documents Department

High-performance GaAs/AlGaAs optical phase modulators for microwave/photonic integrated circuits

Description: High-speed high-performance optical phase modulators are being developed for use in a coherent Photonic Integrated Circuit (PIC) technology. These phase modulators are the critical component of a PIC program at Sandia National Laboratories targeted for microwave/millimeter-wave signal processing and control including phased-array antenna control. The primary design goals for these modulators are amenability for integration into PICs, high ``figure of merit`` (FOM -- phase shift per unit length-voltage), and large bandwidths allowing for operation at millimeter wave frequencies. Depletion-edge-translation optical phase modulators (GaAs/AlGaAs based) have been selected as the device technology of choice due to their high FOM (>60{degree}/V{center_dot}mm @ 1.3 {mu}m). These modulators unfortunately suffer from a large terminal capacitance which greatly limits speed. To overcome this problem, a distributed electrode design based on the use of slow-wave coplanar strips has been developed. Device design and measurements are presented in this paper.
Date: December 31, 1993
Creator: Hietala, V. M.; Kravitz, S. H.; Armendariz, M. G.; Vawter, G. A.; Carson, R. F. & Leibenguth, R. E.
Partner: UNT Libraries Government Documents Department

Cl{sub 2}+Ar reactive-ion-beam etching of InGaAlAs for smooth, low- damage definition of asymmetric Fabry-Perot optical transmission modulators

Description: Cl{sub 2}+Ar Reactive-Ion-Beam Etching is demonstrated for anisotropic, low-damage etching of InAlGaAs semiconductor alloys for use as optical transmission modulators at 1.32 {mu}m wavelength.
Date: July 1, 1996
Creator: Vawter, G.A.; Fritz, I.J.; Drummond, T.J.; Lee, S.R.; Hafich, M.J.; Armendariz, M.G. et al.
Partner: UNT Libraries Government Documents Department