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in creator/contributor: "Baca, A. G."

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Non-alloyed, refractory metal contact optimization with shallow implantations of Zn and Mg

Refractory metal contacts to GaAs show great promise for stability during high-temperature processing and for high-reliability. In this paper the authors report a study of sputtered tungsten and tungsten silicide contacts to ion implanted p-GaAs with both Zn and Mg implantations. This study focused on refractory contacts to shallow implanted contact layers that are suitable for devices such as JFETs and HBTs. The very different energy loss mechanisms of Zn and Mg ions result in different levels… more

Date: March 22, 1994

Creator: Lovejoy, M. L.; Zolper, J. C.; Sherwin, M. E.; Baca, A. G.; Shul, R. J.; Rieger, D. J. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fiber-optic control of current filaments in high gain photoconductive semiconductor switches

The discovery of current filaments in GaAs photoconductive semiconductor switches (PCSS) raised concerns about the location and density of the current distribution during high gain switching. This paper describes experiments using fiber-optic coupled laser diode arrays (LDA) to control the location and number of current filaments in GaAs PCSS. Infrared (IR) images of the recombination radiation, that is emitted from the surface of the PCSS, show precisely where the current is concentrated. Thes… more

Date: August 1, 1994

Creator: Zutavern, F. J.; Loubriel, G. M.; Helgeson, W. D.; O`Malley, M. W.; Gallegos, R. R.; Baca, A. G. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Complementary GaAs junction-gated heterostructure field effect transistor technology

The first circuit results for a new GaAs complementary logic technology are presented. The technology allows for Independently optimizable p- and n- channel transistors with junction gates. Excellent loaded gate delays of 179 ps at 1.2 V and 319 ps at 0.8 V have been demonstrated at low power supply voltages. A power-delay product of 8.9 fJ was obtained at 0.8 V.

Date: September 1, 1994

Creator: Baca, A. G.; Zolper, J. C.; Sherwin, M. E.; Robertson, P. J.; Shul, R. J.; Howard, A. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High gain GaAs switches for impulse sources: Measurement of the speed of current filaments

A high peak power impulse pulser that is controlled with high gain, optically triggered GaAs Photoconductive Semiconductor Switches (PCSS) has been constructed and tested. The system has a short 50 ohm line that is charged to 100 kV and discharged through the switch when the switch is triggered with as little as 90 nJ of laser energy. The authors have demonstrated that the GaAs switches can be used to produce either a monocycle or a monopulse with a period of total duration of about 3 ns. For t… more

Date: July 1, 1994

Creator: Loubriel, G. M.; Zutavern, F. J.; O`Maliey, M. W.; Gallegos, R. R.; Helgeson, W. D.; Hjalmarson, H. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Depth and Thermal Stability of Dry Etch Damage in GaN Schottky Diodes

GaN Schottky diodes were exposed to N2 or H2 Inductively Coupled Plasmas prior to deposition of the rectifying contact. Subsequent annealing, wet photochemical etching or (NH4)2S surface passivation treatments were examined for their effect on diode current- voltage characteristics. We found that either annealing at 750 °C under N2, or removal of ~500-600 Å of the surface essentially restored the initial I-V characteristics. There… more

Date: July 6, 1999

Creator: Baca, A. G.; Cao, X. A.; Cho, H.; Dang, G. T.; Hickman, R.; Pearton, S. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cl{sub 2}/Ar High Density Plasma Damage in GaN Schotky Diodes

No Description Available.

Date: June 28, 1999

Creator: Zhang, A. P.; Dang, G.; Ren, F.; Cao, X. A.; Cho, H.; Lambers, E. S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ion implantation processing for high-speed GaAs JFETs

GaAs Junction Field Effect Transistors (JFETs) offer a higher gate turn-on voltage, resulting in a better noise margin and reduced power dissipation, than the more widely employed GaAs MESFET. The primary reason the JFET has not been more widely used is the speed penalty associated with the gate/channel junction and corresponding gate length broadening. We present the ion implantation processes used for a self-aligned, all ion-implanted, GaAs JFET that minimizes the speed penalty for the JFET w… more

Date: July 1, 1995

Creator: Zolper, J. C.; Baca, A. G.; Sherwin, M. E. & Shul, R. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photoconductive semiconductor switches for firing sets and electro-optic modulators

Optically activated GaAs switches operated in their high main mode are being used or tested for pulsed power applications as diverse as low impedance, high current pursers, and high impedance, low current Pockels cell or Q switch drivers. These are important to firing sets in munitions, lasers used in detonation of munitions, and lasers used in large weapons effects simulators (such as Jupiter). For firing, sets we have switched 2.8 kA at 3 kV dc charge in a very compact package. For driving Q … more

Date: July 1, 1995

Creator: Loubriel, G. M.; Zutavern, F. J.; Baca, A. G.; Hjalmarson, H. P.; Helgeson, W. D. & O`Malley, M. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Self-Aligned GaAs JFETs for Low-Power Microwave Amplifiers and RFICs at 2.4 GHz

Self-aligned GaAs JFET narrowband amplifiers operating at 2.4 GHz were designed and fabricated with both discrete WETS as a hybrid amplifier and as RFICS. Enhancement-mode JFETs were used in order to be compatible with complementary digital logic. Hybrid amplifiers achieved 8-10 dB of gain at 2.4 GHz and 1 mW DC bias level. The RFIC achieved 10 dB of gain at 24 GHz and 2 mW DC bias level.

Date: November 2, 1998

Creator: Baca, A. G.; Dubbert, D. F.; Greenway, D.; Hietala, V. M.; Shul, R. J.; Sloan, L. R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Atomic force microscopy as a process characterization tool for GaAs-based integrated circuit fabrication

While developing the fabrication process for GaAs-based integrated circuits numerous situations have been encountered where an in-line and post-process characterization tool which operates in a non-destructive manner was required. We will report several examples which demonstrate that the atomic force microscope (AFM) fills this characterization void in our laboratory. The AFM is extremely useful where the unintentional removal of small amounts of GaAs can be detrimental in the fabrication of d… more

Date: February 1, 1995

Creator: Howard, A. J.; Baca, A. G.; Shul, R. J.; Zolper, J. C.; Sherwin, M. E. & Rieger, D. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Thermally stable oxygen and nitrogen implant isolation of C-doped Al{sub 0.35}Ga{sub 0.65}As

Oxygen and nitrogen ion implantation have been applied to C-doped Al{sub 0.35}Ga{sub 0.65}As layers to produce high resistivity regions ({rho}{sub s} {ge} l {times} 10{sup 10} {Omega}/{open_square} that are stable after annealing at 900C. A dose threshold for stable compensation for both O and N ions was found above 8 {times} 10{sup l3} cm{sup {minus}2} for samples doped at 2 {times} 10{sup l8} cm{sup {minus}3}. Although O implantation has been reported to form stable compensation in Si-doped a… more

Date: December 31, 1993

Creator: Zolper, J. C.; Sherwin, M. E.; Baca, A. G. & Schneider, R. P. Jr.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High current density contacts for photoconductive semiconductor switches

The current densities implied by current filaments in GaAs photoconductive semiconductor switches (PCSS) are in excess of 1 MA/cm{sup 2}. As the lateral switches are tested repeatedly, damage accumulates at the contacts until electrical breakdown occurs across the surface of the insulating region. In order to improve the switch lifetime, the incorporation of n- and p-type ohmic contacts in lateral switches as well as surface geometry modifications have been investigated. By using p-type AuBe oh… more

Date: August 1, 1993

Creator: Baca, A. G.; Hjalmarson, H. P.; Loubriel, G. M.; McLaughlin, D. L. & Zutavern, F. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Plasma-induced-damage of GaAs during etching of refractory metal contacts

The effect of plasma-induced-damage on the majority carrier transport properties of GaAs has been studied by monitoring changes in sheet resistance (R{sub s}) of thin conducting layers under various plasma conditions including etch conditions for refractory metal contacts. R{sub s} determined from transmission line measurements are used to evaluate plasma-induced-damage for electron cyclotron resonance (ECR) and reactive ion etch (RIE) conditions by varying the thickness of doped epitaxial laye… more

Date: October 1, 1994

Creator: Shul, R. J.; Lovejoy, M. L.; Baca, A. G.; Zolper, J. C.; Rieger, D. J.; Hafich, M. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Complementary GaAs junction-gated heterostructure field effect transistor fabrication for integrated circuits

A new GaAs junction-gated complementary logic technology that integrates a modulation doped p-channel heterostructure field effect transistor (pHFET) and a fully ion implanted n-channel JFET has recently been fabricated. High-speed, low-power operation has been demonstrated with loaded ring oscillators that show gate delays of 179 ps/stage for a power-delay product of 28 fJ at 1.2 V operation and 320 ps/stage and 8.9 fJ at 0.8 V operation. The principal advantages of this technology include the… more

Date: October 1, 1994

Creator: Baca, A. G.; Zolper, J. C.; Sherwin, M. E.; Robertson, P. J.; Shul, R. J.; Howard, A. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High gain GaAs Photoconductive Semiconductor Switches (PCSS): Device lifetime, high current testing, optical pulse generators

This paper presents results from three areas of GaAs PCSS research and development: device lifetime, high current switching, and PCSS-driven laser diode arrays (LDA). The authors have performed device lifetime tests on both lateral and vertical switches as a function of current amplitude, pulse width, and charging time. At present, their longest-lived switch reached 4 {times} 10{sup 6} pulses. Scanning electron microscope (SEM) images show damage near the contacts even after only 5 pulses. They… more

Date: December 31, 1995

Creator: Zutavern, F. J.; Loubriel, G. M.; Helgeson, W. D.; O`Malley, M. W.; Gallegos, R. R.; Hjalmarson, H. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of High-Voltage Heterojunction Bipolar Transistor Collector Design on f(T) and f(MAX)

High-speed InGaP/GaAs heterojunction bipolar transistors (HBTs) for high-voltage circuit applications have been investigated. In order to obtain ideal IV characteristics, a lightly doped (N{sub DC} = 7.5 x 10{sup 15} cm{sup {minus}3}) thick (W{sub C} = 3.5 {micro}m) layer of GaAs was used as the collector layer. The devices fabricated have shown breakdown voltage exceeding 65 V. Device operated at up to a 60V bias, which is the highest operating voltage reported up to date for single heterojunc… more

Date: March 2, 1999

Creator: Ashby, C. I. H.; Baca, A. G.; Chang, P. C. & Hietala, V. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Gas Phase Chemical Detection with an Integrated Chemical Analysis System

No Description Available.

Date: October 9, 2000

Creator: Casalnuovo, S. A.; Frye-Mason, G. C.; Kottenstette, R.; Heller, E. J.; Matzke, C. M.; Lewis, P. R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Oxygen Implant Isolation of n-GaN Field-Effect Transistor Structures

Multiple-energy (30-325 keV) O{sup +} implantation into GaN field-effect transistor structures (n {approximately} 10{sup 18} cm{sup {minus}3}, 3000 {angstrom} thick) can produce as-implanted sheet resistances of 4 x 10{sup 12} {Omega}/{open_square}, provided care is taken to ensure compensation of the region up to the projected range of the lowest energy implant. The sheet resistance remains above 10{sup 7} {Omega}/{open_square} to annealing temperatures of {approximately} 650 C and displays an… more

Date: July 20, 1999

Creator: Dang, G.; Cao, X. A.; Ren, F.; Pearton, S. J.; Han, J.; Baca, A. G. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A Gaas Heterojunction Bipolar Transistor With 106 v Breakdown

A high voltage GaAs HBT with an open-base collector breakdown voltage of 106 V and an open-emitter breakdown voltage of 134 V has been demonstrated. A high quality 9.0 {micro}m thick collector doped to 2.0{times}10{sup 15} cm{sup {minus}3} grown by MBE on a doped GaAs substrate is the key to achieving this breakdown. These results were achieved for HBTs with 4{times}40 {micro}m{sup 2} emitters. DC current gain of 38 at 6,000 A/cm{sup 2} was measured.

Date: January 11, 2000

Creator: Baca, A. G.; Klem, J. F.; Ashby, C. I. & Martin, D. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Non-Destructive Inter-Level Dielectric via in-Line Process Monitoring by Atomic Force Microscopy

A new application using atomic force microscopy (AFM) for in-line process control monitoring (PCM) of an interlevel dielectric via etching step is reported. The AFM with its near atomic-level resolution is capable of nondestructively measuring whether micron-sized vias have been etched to completion. Etch completion is determined by comparing the AFM measured etch depth of adjacent via holes through {approximately}4000 {Angstrom} thick Si{sub 3}N{sub 4} over Au-based ohmic and W gate metallizat… more

Date: December 31, 1994

Creator: Howard, A. J.; Baca, A. G. & Shul, R. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ingaas/Inp Heterojunction Bipolar Transistors for Ultra-Low Power Circuit Applications

For many modern day portable electronic applications, low power high speed devices have become very desirable. Very high values of f{sub T} and f{sub MAX} have been reported with InGaAs/InP heterojunction bipolar transistors (HBTs), but only under high bias and high current level operating conditions. An InGaAs/InP ultra-lowpower HBT with f{sub MAX} greater than 10 GHz operating at less than 20 {micro}A has been reported for the first time in this work. The results are obtained on a 2.5 x 5 {mi… more

Date: August 1, 1998

Creator: Chang, P. C.; Baca, A. G.; Hafich, M. J. & Ashby, C. I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Comparison of InP/InGaAs HBT and InAlAs/InGaAs HBT for ULP Applications

The increased demand for portable electronics has lead to the need for higher performance and efficiency. Devices operating at less than 50 {micro}W of power are defined as ultra-low-power (ULP) devices. New progress has been achieved on InP/InGaAs HBT and InAIAs/InGaAs HBT optimized for ULP applications. f{sub T} values of 2.2 GHz, and f{sub MAX} values of 20 GHz have been obtained for HBTs operating at less than 40 {micro}W. Current gain is greater than 45 with the device operating at less th… more

Date: July 7, 1999

Creator: Ashby, C. I. H.; Baca, A. G.; Chang, P. C.; Hafich, M. J.; Hietala, V. M. & Klem, J. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of a GaAs-Based Monolithic Surface Acoustic Wave Integrated Chemical Microsensor

An oscillator technology using surface acoustic wave delay lines integrated with GaAs MESFET electronics has been developed for GaAs-based integrated microsensor applications. Oscillators with frequencies of 470, 350, and 200 MHz have been designed and fabricated. These oscillators are also promising for other rf applications.

Date: October 28, 1998

Creator: Baca, A. G.; Casalnuovo, S. C.; Drummond, T. J.; Frye, G. C.; Heller, E. J.; Hietala, V. M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Compound Semiconductor Devices for Low-Power High-Efficiency Radio Frequency Electronics

The power consumption of Radio Frequency (RF) electronics is a significant issue for Wireless systems. Since most wireless systems are portable and thus battery operated, reductions in DC power consumption can significantly reduce the weight and/or increase the battery lifetime of the system. As transmission consumes significantly more power than reception for most Wireless applications, previous efforts have been focused on increasing the efficiency of RF power amplification. These efforts hav… more

Date: February 18, 1999

Creator: Baca, A. G.; Chang, P. C.; Hietala, V. M. & Sloan, L. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department