Prospects of (100)p-NiO/(0001)n-ZnO Heterostructures for UV Photodetection and Artificial Synaptic Devices

We investigate the photo-response properties of (100)p-NiO/(0001)n-ZnO heterostructures. Our study reveals that these devices can serve as effective UV photodetectors with response time of few hundred microseconds in the self-powered mode. Peak responsivity of these devices has been found to be as high as 5mA/W at zero bias condition. Furthermore, the response time of these detectors can be electrically controlled over a large range, from several microseconds to several hundreds of seconds, by applying bias above a threshold in both forward and reverse directions. The origin of which has been explained in terms of traps at the interface. Above the threshold bias, these devices exhibit synaptic behaviors, like the biological synapses, exhibiting short-term-memory (STM) to long-term-memory (LTM) transition as well as learning-forgetting processes. Moreover, in this system, memory can be partially or completely erased by electrical stimulation. These devices, which are found to consume as low as 128nJ of electrical and 179nJ of optical powers per synaptic event, demonstrate satisfactory performance in terms of repeatability and stability. These findings underscore the potential of (100) p-NiO/(0001)n-ZnO heterojunctions in the development of next-generation photodetectors and neuromorphic devices.