Improvement of metal-semiconductor-metal GaN photoconductors

Metal-semiconductor-metal photoconductors made on GaN usually exhibit a slow response time and a low responsivity. We have carried out a systematic study on the performance of the photoconductors made from GaN grown by metalorganic chemical vapor deposition using different growth conditions and have found that both response time and responsivity of the GaN detector are improved when the material is grown using increased ammonia flow rates. The best GaN ultraviolet photoconductive detector shows a response time of 0.3 ms and a responsivity of 3200 A/W at 365 nm under an operation bias of 10 V. We attribute this improvement to the reduction of the point defects in GaN.