Accession Number : AD0473767


Title :   FIRE AND EXPLOSION DETECTION FOR ADVANCED FLIGHT VEHICLES.


Descriptive Note : Final rept. 1 Mar-30 Sep 65,


Corporate Author : WESTINGHOUSE RESEARCH LABS PITTSBURGH PA


Personal Author(s) : Chang, Henry C ; Campbell, Robert B


Report Date : Nov 1965


Pagination or Media Count : 40


Abstract : The fabrication of high temperature ultraviolet radiation detectors from semiconducting SiC diffused junctions has been shown practicable. Such detectors, using the photovoltaic principle would be useful in systems for detecting fire and explosions. The SiC crystals were grown by the sublimation method and the junctions were prepared by aluminum diffusion. It was found that the wavelength at which the peak response occurred was dependent on the junction depth. Peak response near 2850 A required the junctions to be less than one micron deep. Photovoltages from 0.5 V to 0.001 volt were measured. Since the formation of such shallow junctions is difficult to control, several methods of removing the surface of the diode uniformly were studied. The best results were obtained using the technique of thermal oxidation and HF etching. The wavelength at peak response increased and the photovoltage degraded as a function of temperature. However, several diodes showed adequate response above 500 C to be usable as detectors. Both the peak wavelength as a function of junction depth and the variation of the peak wavelength with temperature can be quantitatively explained by considering the absorption coefficient of SiC below the band edge. (Author)


Descriptors :   *ULTRAVIOLET DETECTORS , *FIRES , *EXPLOSIONS , SILICON COMPOUNDS , ULTRAVIOLET RADIATION , ULTRAVIOLET RADIATION , CARBIDES , MANUFACTURING , CRYSTAL GROWTH , SUBLIMATION , SEMICONDUCTOR DIODES , CRYSTAL DETECTORS , ETCHED CRYSTALS , MEASUREMENT , RADIATION MEASURING INSTRUMENTS , ENCAPSULATION , DETECTION , AIRCRAFT FIRES , WARNING SYSTEMS


Distribution Statement : APPROVED FOR PUBLIC RELEASE