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in creator/contributor: "Zutavern, F. J."

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Longevity of optically activated, high gain GaAs photoconductive semiconductor switches

The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to well over 10 million pulses by reducing the density of carriers at the semiconductor to metal interface. This was achieved by reducing the density in the vertical and lateral directions. The first was achieved by varying the spatial distribution of the trigger light thereby widening the current filaments that are characteristic of the high gain switches. The authors reduced the carrier density in … more

Date: August 1, 1997

Creator: Loubriel, G. M.; Zutavern, F. J. & Mar, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

An impact ionization model for optically-triggered current filaments in GaAs

A new impact ionization theory is proposed for current filaments in optically triggered semi-insulating (SI) GaAs switches. The theory explains the rapid switching and lock-on voltage observed in these switches in terms of hot carriers which become more effective at impact ionization at higher carrier densities. The theory is implemented by hydrodynamic transport equations which include kinetic terms for hot carriers and hot phonons. The solutions of these equations are in good agreement with c… more

Date: December 1, 1996

Creator: Hjalmarson, H. P.; Zutavern, F. J. & Loubriel, G. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Diamond switches for high temperature electronics

This paper presents the results of switching voltages of 500 V and currents of 10 A using chemical vapor deposited (CVD) diamond as a switching material. The switching is performed by using an electron beam that penetrates the diamond, creates electron hole pairs, and lowers its resistivity to about 20 {Omega}-cm and its resistance to about 4 {Omega}. Tests were performed at room temperature but in a configuration that allows for 250 C.

Date: June 1, 1997

Creator: Loubriel, G. M.; Zutavern, F. J. & Ruebush, M. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ground penetrating radar enabled by high gain GaAs photoconductive semiconductor switches

The ability of high gain GaAs Photoconductive Semiconductor switches (PCSS) to deliver fast risetime, low jitter pulses when triggered with small laser diode arrays makes them suitable for their use in ultrawide bandwidth (UWB), impulse transmitters. This paper will summarize the state-of-the-art in high gain GaAs switches and discuss how GaAs switches are being implemented in a transmitter for detection of underground structures. The advantage of this type of semiconductor switch is demonstrat… more

Date: June 1, 1996

Creator: Loubriel, G. M.; Buttram, M. T.; Aurand, J. F. & Zutavern, F. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High gain GaAs photoconductive semiconductor switches: Switch longevity

Optically activated, high gain GaAs switches are being tested for many different pulsed power applications that require long lifetime (longevity). The switches have p and n contact metallization (with intentional or unintentional dopants) configured in such a way as to produce p-i-n or n-i-n switches. The longevity of the switches is determined by circuit parameters and by the ability of the contacts to resist erosion. This paper will describe how the switches performed in test-beds designed to… more

Date: July 1, 1998

Creator: Loubriel, G. M.; Zutavern, F. J. & Mar, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High gain GaAs photoconductive semiconductor switches: Measurement of filament velocity and reduced trigger energy

The time evolution of the current filaments in an optically triggered, high gain GaAs switch was studied by recording the infrared photoluminescence from the filaments. When the switch is triggered with two laser diode arrays (through a fiber optic) that are activated within 1 ns of each other, two current filaments are observed, each one emanating from the point of illumination. By delaying one laser with respect to the other, the evolution of the filament was recorded in a time resolved fashi… more

Date: November 1, 1994

Creator: Loubriel, G. M.; Zutavern, F. J.; O`Malley, M. W. & Helgeson, W. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High gain GaAs Photoconductive Semiconductor Switches for impulse sources

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 {Omega} 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. We have demonstrated that the GaAs switches can be used to produce either a monocycle or a monopulse with a period or total duration of about 3 ns. For the mo… more

Date: November 1, 1994

Creator: Loubriel, G. M.; Zutavern, F. J.; O`Malley, M. W. & Helgeson, W. D.

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

The use of optically triggered, high gain GaAs switches for UWB pulse generation

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 {Omega} 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 laser that is used is a small laser diode array whose output is delivered through a fiber to the switch. The current in the system ranges from 1 kA (with … more

Date: April 1, 1994

Creator: Loubriel, G. M.; Zutavern, F. J.; O`Malley, M. W.; Gallegos, R. R. & Helgeson, W. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration

This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered w… more

Date: December 1, 1997

Creator: Loubriel, G. M.; Mar, A.; Hamil, R. A.; Zutavern, F. J. & Helgeson, W. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A compact, short-pulse laser for near-field, range-gated imaging

This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low imped… more

Date: December 31, 1996

Creator: Zutavern, F. J.; Helgeson, W. D.; Loubriel, G. M.; Yates, G. J.; Gallegos, R. A. & McDonald, T. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Influence of electrode geometry on the high-field characteristics of photoconductive silicon wafers

A series of experiment were conducted to study the influence of electrode geometry on the prebreakdown (and breakdown) characteristics of high resistivity ({rho} > 30 k{Omega}-cm), p-type Si wafers under quasi-uniform and non-uniform electric field configurations. In the quasi-uniform field configuration, the 1mm thick Si wafer was mounted between the slots of two plane parallel stainless steel disc electrodes (parallel), while the non-uniform field was obtained by mounting the wafer between tw… more

Date: July 1, 1994

Creator: Madangarli, V. P.; Gradinaru, G.; Korony, G.; Sudarshan, T. S.; Loubriel, G. M.; Zutavern, F. J. et al.

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

Optically controlled current filamentation in GaAs photoconductive semiconductor switches

The use of focused laser beams and fiber optics to control the location and density of current filaments in GaAs photoconductive semiconductor switches (PCSS) is described in this paper. An intensified CCD camera is used to monitor the infrared photoluminescence of the filaments during fast initiation of high gain switching for several sizes of lateral GaAs PCSS (e. g. 0.5{times}5, 1{times}5, 2.5{times}5, 2{times}30, and 15{times}20 mm{sup 2}). The switches are triggered with either a focused, … more

Date: August 1, 1993

Creator: Zutavern, F. J.; Baca, A.; Helgeson, W. D.; Hjalmarson, H. P.; Loubriel, G. M.; McLaughlin, D. L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photoconductive Semiconductor Switches for pulsed power applications

Photoconductive Semiconductor Switches (PCSS) are being used in, or tested for, many different pulsed power applications as diverse as ultrawideband (UWB) transmitters and high current pulsers. Some aspects of the switches that are relevant to most of the applications are: switch lifetime (longevity), switch opening time (related to the lifetime of carriers in the semiconductor), switching jitter, and the required laser energy. This paper will emphasize the results that we have obtained with Si… more

Date: August 1, 1993

Creator: Loubriel, G. M.; Zutavern, F. J.; Denison, G. J.; Helgeson, W. D.; McLaughlin, D. L.; O`Malley, M. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High gain GaAs photoconductive semiconductor switches for ground penetrating radar

The ability of high gain GaAs Photoconductive Semiconductor switches (PCSS) to deliver high peak power, fast risetime pulses when triggered with small laser diode arrays makes them suitable for their use in radars that rely on fast impulses. This type of direct time domain radar is uniquely suited for observation of large structures under ground because it can operate at low frequencies and at high average power. This paper will summarize the state-of-the-art in high gain GaAs switches and disc… more

Date: July 1, 1996

Creator: Loubriel, G. M.; Aurand, J. F.; Buttram, M. T.; Zutavern, F. J.; Helgeson, W. D.; O`Malley, M. W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Properties of high gain GaAs switches for pulsed power applications

High gain GaAs photoconductive semiconductor switches (PCSS) are being used in a variety of electrical and optical short pulse applications. The highest power application, which the authors are developing, is a compact, repetitive, short pulse linear induction accelerator. The array of PCSS, which drive the accelerator, will switch 75 kA and 250 kV in 30 ns long pulses at 50 Hz. The accelerator will produce a 700 kV, 7kA electron beam for industrial and military applications. In the low power r… more

Date: September 1, 1997

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

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Rise Time and Recovery of GaAs Photoconductive Semiconductor Switches

Fast rise time applications have encouraged us to look at the rise time dependences of lock-on switching. Our tests have shown rise time and delay effects which decrease dramatically with increasing electric field across the switch and/or optical energy used in activating lock-on. Interest in high repetition rate photoconductive semiconductor switches (PCSS), which require very little trigger energy (our 1.5-cm long switches have been triggered with as little as 20 {mu}J), has also led us to in… more

Date: January 1, 1990

Creator: Zutavern, F. J.; Loubriel, G. M.; O'Malley, M. W.; McLaughlin, D. L. & Helgeson, W. D.

Item Type: Article

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

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

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

Triggering GaAs lock-on switches with laser diode arrays

Many of the applications that require the unique capabilities of Photoconductive Semiconductor Switches (PCSS) demand a compact package. We have been able to demonstrate that GaAs switches operated in the high gain mode called lock-on'' meet the required electrical switching parameters of several such applications using small switch sizes. The only light source that has enough power to trigger a PCSS and is compatible with a small package is a laser diode. This paper will describe the progress … more

Date: January 1, 1990

Creator: Loubriel, G. M.; Helgeson, W. D.; McLaughlin, D. L.; O'Malley, M. W.; Zutavern, F. J.; Rosen, A. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Final Report of LDRD Project: An Electromagnetic Imaging System for Environmental Site Reconnaissance

This report provides a summary of the LDRD project titled: An Electromagnetic Imaging System for Environmental Site Reconnaissance. The major initial challenge of this LDRD was to develop a ground penetrating radar (GPR) whose peak and average radiated power surpassed that of any other in existence. Goals were set to use such a system to detect the following: (1) disrupted soil layers where there is potential for buried waste, (2) buried objects such as 55-gallon drums at depths up to 3 m, and … more

Date: December 1, 2000

Creator: Denison, G. J.; Loubriel, G. M.; Buttram, M. T.; Rinehart, L. F.; Helgeson, W.; Brown, D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Optically-Activated GaAs Switches for Ground Penetrating Radar and Firing Set Applications

Optically activated, high gain GaAs switches are being tested for many different applications. TWO such applications are ground penetrating radar (GPR) and firing set switches. The ability of high gain GaAs Photoconductive Semiconductor Switches (PCSs) to deliver fast risetime pulses makes them suitable for their use in radars that rely on fast impulses. This type of direct time domain radar is uniquely suited for the detection of buried items because it can operate at low frequency, high avera… more

Date: July 14, 1999

Creator: Aurand, J.; Brown, D. J.; Carin, L.; Denison, G. J.; Helgeson, W. D.; Loubriel, G. M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department