Accession Number : ADA313853

Title :   SiC for High Power Electro-Optic Switching Application.

Descriptive Note : Final rept. 20 Sep 93-19 Sep 95,

Corporate Author : HOWARD UNIV WASHINGTON DC SCHOOL OF ENGINEERING

Personal Author(s) : Spencer, Michael G. ; Sheng, Senpeng

PDF Url : ADA313853

Report Date : SEP 1996

Pagination or Media Count : 67

Abstract : Photoconductive semiconductor switches have unique advantages such as high power, speed, negligible time jitter and long lifetime. Silicon carbide (SiC), due to its high dielectric strength and other desired properties, is an excellent material for photoconductive switches. However, no appreciable result has been reported on cubic silicon carbide (3C-SiC) photoconductive switches. In this research, photoconductive switches were fabricated on the following three types of 3C-SiC substrates: (i) boron doped, (ii) unintentionally doped single crystals and (iii) polycrystalline 3C-SiC. The switches were investigated using ArF and XeCl excimer lasers. Practical switches with many potential applications were successfully fabricated. The best results were obtained from the switches made from the polycrystalline material. The dark resistivity of the material was about 10(exp 6) ohms cm. The operating breakdown field was 2.5 x 10(exp 5) V/cm, which is the highest reported for all lateral geometry photoconductive switches, and was limited by the surface flashover effects. The highest peak photocurrent density through the switches was about 10 kA/sq cm. The ratio of the off-state resistance to the on-state resistance (Roff/Ron) was approx. 10(exp 5), and the lowest on-state resistance was 45 ohms. The width of the photocurrent pulse was 15 to 30 ns which was limited by the laser pulse, indicating that the switches can operate in the megahertz range.

Descriptors :   *HIGH POWER, *ELECTROOPTICS, *ELECTRIC SWITCHES, *SILICON CARBIDES, *PHOTOCONDUCTIVITY, HIGH FREQUENCY, MATERIALS, RESISTANCE, SINGLE CRYSTALS, SEMICONDUCTOR DEVICES, CRYSTALS, PULSED LASERS, LASERS, SURFACES, HIGH STRENGTH, HIGH DENSITY, LONG LIFE, DOPING, ELECTRIC CURRENT, DIELECTRIC STRENGTH, BORON, EXCIMERS, ELECTRONIC SWITCHES, POLYCRYSTALLINE, PHOTOELECTRICITY, JITTER.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Radiation and Nuclear Chemistry
      Electrooptical and Optoelectronic Devices
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE