Novel ZnO thin-film based Piezo-photonic low VUV detector for cryogenic applications

We demonstrate a novel detection scheme utilizing the piezo-pyroelectric properties of ZnO thin films for a zero-bias vacuum ultraviolet (VUV) detector. We present results from our measurements that stress-induced in ZnO thin films through interface strain engineering can lead to an enhancement of the VUV photoinduced signals. We compare the signals from a bare ZnO detector to a detector with an additional silicon nitride layer that introduces the stress-induced piezo potential. As a control, a non-piezoelectric material was used as a substitute for the ZnO film to validate our hypothesis that the stress-induced enhancement is due to piezo potential. Additionally, we demonstrate the detector's performance at cryogenic temperatures, and the results are discussed based on piezo and pyroelectric potential induced in ZnO thin film. COMSOL simulations of the stress and temperature variation-induced potential in bare ZnO and in a ZnO/silicon nitride heterostructure have been used to optimize the device architecture. Such a photodetector can have applications in rare event searches in high energy physics using liquid noble detectors, as a UV detector for space-based sensors, and in other environments where low-power cryogenic performance is needed.