A BORON PHOSPHIDE SEMICONDUCTOR NEUTRON DETECTOR

SINCE THEIR DISCOVERY NEUTRONS HAVE REMAINED ONE OF THE MOST DIFFICULT FORMS OF RADIATION TO DETECT. THE MOST EFFECTIVE NEUTRON DETECTORS IN CURRENT USE ARE GAS FILLED DETECTORS EMPLOYING EITHER 3HE OR BF3 AS THE DETECTION MEDIUM. UNFORTUNATELY, GAS FILLED DETECTORS SUFFER FROM A NUMBER OF DEFICIENCIES INCLUDING LARGE SIZE (GASES HAVE LOW VOLUMETRIC EFFICIENCY FOR STOPPING NEUTRONS), MECHANICAL FRAGILITY, AND HIGH VOLTAGE MEASUREMENTS. WE PROPOSE TO DEVELOP A NEW FORM OF SOLID STATE NEUTRON DETECTOR FROM THE SEMICONDUCTING COMPOUND BORON PHOSPHIDE. BORON PHOSPHIDE POSSESSES MOST OF THE DESIRABLE ELECTRICAL PROPERTIES OF SIMILAR III-V COMPOUNDS, WHICH HAVE ALLOWED PRODUCTION OF SEMICONDUCTING DETECTORS FROM GAAS AND INP. BECAUSE BORON PHOSPHIDE IS A SOLID THAT CONTAINS BORON AS A STOICHIOMETRIC COMPONENT, IT HAS A HIGH STOPPING EFFICIENCY FOR THERMAL NEUTRONS. USEFUL CRYSTALS OF BORON PHOSPHIDE ARE VERY DIFFICULT TO OBTAIN DUE TO THEIR HIGH MELTING POINT. RECENTLY, HOWEVER, RESEARCHERS HAVE BEEN ABLE TO GROW THICK FILMS ON SILICON SUBSTRATES BY CHEMICAL VAPOR DEPOSITION METHODS. IT IS PROPOSED TO USE SIMILAR TECHNIQUES TO GROW BP/SI HETEROJUNCTION DIODES CAPABLE OF EFFICIENT NEUTRON DETECTION. NEUTRON DETECTORS MADE FROM BORON PHOSPHIDE WOULD BE VASTLY SUPERIOR TO THE GAS DETECTORS CURRENTLY IN USE AND MAY ALSO BE EXTREMELY PROMISING FOR BUILDING ARRAYS OF DETECTORS WITH HIGH SPATIAL RESOLUTION.