ZnO ultraviolet photodetectors with an extremely high detectivity and short response time

ZnO thin films have been prepared by atomic layer deposition for ultraviolet photodetection with metal-semiconductor-metal (MSM) structure. The innovation of rapid thermal annealing treatment can modulate the carrier concentration of the ZnO thin films, a lowest carrier concentration of 4.4 x 10(14) cm(-3) was obtained after annealing at 450 degrees C, resulting in the minimum dark current of 4.5 x 10(-8) A at 5 V. Furthermore, these photodetectors demonstrated respectable responsivity of up to 27 A/W, and the detectivity was enhanced to a fairly high value of 8.5 x 10(13) Hz(1/2)/W together with an extremely rapid response of < 80 mu s. These performance metrics are far superior compared with the records in the existing literature based on ZnO thin films, and are even on a par with nano-structural ZnO devices, while remain the key features of thin film devices, including high reproducibility and facile preparation.