A WIDE TUNABLE ULTRAVIOLET DETECTOR FOR A CHERENKOV PARTICLE DETECTION SYSTEM USING GALLIUM-NITRIDE/ALUMINUM-GALLIUM-NITRIDE MULTIPLE QUANTUM WELL STRUCTURES

THE WEAK ULTRAVIOLET (UV) LIGHT GENERATED BY CHARGED PARTICLES TRAVERSING AN APPROPRIATE MEDIUM IN A RING-IMAGING CERENKOV (RICH) DETECTION SYSTEM REQUIRES A VERY SENSITIVE DETECTOR ARRAY TO GIVE THE SPATIAL LOCATION AND THE VELOCITY VECTOR OF THE PARTICLES. THE LOW SENSITIVITY OF COMMERCIALLY AVAILABLE UV DETECTORS REQUIRES THE IMPLEMENTATION OF AN EXTERNAL IMAGE INTENSIFIER, WHICH IS BULKY, EXPENSIVE, AND FRAGILE. IT IS PLANNED TO FABRICATE A UV AVALANCHE DETECTOR ARRAY FOR IDENTIFYING THE CHARGED PARTICLES IN RICH DETECTORS. THE NOVELTY OF THIS UV DETECTOR IS THE AVALANCHE EFFECT VIA IMPACT IONIZATION OF ELECTRONS AND HOLES IN A GALLIUM NITRIDE/ALUMINUM GALLIUM NITRIDE MULTIQUANTUM WELL (MQW) STRUCTURE. THE MQW IS DESIGNED TO PROVIDE HIGH EFFICIENCY AND HIGH SPEED OPERATION BY CONTROLLING THE IMPACT IONIZATION RATE OF ELECTRONS AND HOLES SEPARATELY. THE AVALANCHE EFFECT PROVIDES AN INTERNAL GAIN THAT INCREASES THE SENSITIVITY OF THE DETECTOR BY AT LEAST FIVE ORDERS OF MAGNITUDE. THIS WILL ELIMINATE THE USE OF THE EXTERNAL IMAGE INTENSIFIER NEEDED FOR CONVENTIONAL DETECTION SYSTEMS. THIS UV DETECTOR HAS HIGH SENSITIVITY AND A LARGE BANDWIDTH. IN ADDITION, IT IS EFFICIENT, HIGHLY RELIABLE AND COST EFFECTIVE FOR THE RICH SYSTEM. IN PHASE I A PROTOTYPE DEVICE WILL BE FABRICATED TO DEMONSTRATE THE FEASIBILITY OF THIS CONCEPT. IN PHASE II A FULLY FUNCTIONAL DETECTOR ARRAY WILL BE FABRICATED USING THE OPTIMIZED PARAMETERS.