ULTRA HIGH RESISTIVITY SILICON CRYSTALS FOR RADIATION DETECTORS

AVAILIBILITY OF SILICON RADIATION DETECTORS WITH LARGE SENSITIVE DEPTHS HAS BEEN SERIOUSLY RESTRICTED BY LACK OF A GOOD SUPPLY OF VERY HIGH RESISTIVITY, HIGH QUALITY, SINGLE CRYSTALS OF SILICON. THIS PROGRAM IS DIRECTED AT A COST-EFFECTIVE AND RELIABLE METHOD FOR MAKING SILICON FOR DETECTORS WITH SENSITIVE DEPTHS BEYOND SEVERAL MILLIMETERS. THE METHOD IS BASED ON AN INNOVATIVE CONCEPT FOR CIRCUMVENTING THE PROBLEMS CAUSED BY NONUNIFORM DISTRIBUTIONOF IMPURITIES. NONUNIFORM IMPURITY DISTRIBUTION HAS FRUSTRATED MANY PREVIOUS ATTEMPTS TO MAKE STABLE, COMPENSATED, VERY HIGH RESISTIVITY SILICON IN A PREDICTABLE AND COST-EFFECTIVE MANNER. PHASE I WILL CONCENTRATE ON DEVELOPING TECHNIQUES FOR SPECIALIZED MATERIAL EVALUATIONS, ON THE PROCESS FOR RESTORING CHARGE CARRIER LIFETIME AND TRAP-FREE MATERIAL, AND ON PROVING THE FEASIBILITY OF THE CONCEPT. A PHASE II EFFORT WILL BE REQUIRED TO PRODUCE ENOUGH MATERIAL TO VERIFY THE REPRODUCIBLE QUALITY OF THE DETECTOR GRADE CRYSTALS AND THE ABILITY TO MAKE THEM IN QUANTITY AT A REASONABLE COST. A PREDICTABLE COMMERCIALLY VIABLE SOURCE OF ULTRA HIGH RESISTIVITY SILICON HAS ELUDED MANY PREVIOUS INTERNATIONAL EFFORTS. A SOLUTION TO THIS PROBLEM WILL REMOVE MANY DETECTOR DESIGN AND MANUFACTURING LIMITATIONS.