UV photodetectors based on 3D periodic Au-decorated nanocone ZnO films

All 3D-Printed Flexible ZnO UV Photodetector on an Ultraflat Substrate

An all three-dimensional (3D)-printed flexible ZnO ultraviolet (UV) photodetector is demonstrated, where the 3D-printing method is used not only for the electrode and photosensitive material but also for creating a substrate. An ultraflat and flexible substrate capable of serving as the backbone layer is developed using a water-dissolvable polymer layer for surface planarization. A two-layered printing followed by surface treatment is demonstrated for the substrate preparation. As mechanical support but flexible, a thick and sparse thermoplastic polyurethane layer is printed. On its surface, a thin and dense poly(vinyl alcohol) (PVA) is then printed. A precise control of PVA reflow using a microwater droplet results in a flexible and extremely uniform substrate. A Cu-Ag nanowire network is directly 3D printed on the flexible substrate for the conducting layer, followed by ZnO for the photosensitive material. Unlike the planar two-dimensional printing that provides thin films, 3D printing allows the electrode to have a step height, which can be made like a dam to accommodate a thick film of ZnO. Photosensitivity as a function of various ZnO thickness values was investigated to establish an optimal thickness for UV response. The device was also tested in natural sunlight along with stability and reliability.

Surface acoustic wave-based ultraviolet photodetectors: a review

Over the past decade, ultraviolet (UV) detection has been a subject of major interest for both research scientists and engineers because of its important applications in both the civil and military fields. The rapid development of interdisciplinary research has enabled the realization of UV detectors based on a variety of principles. Among these devices, UV detectors based on surface acoustic wave (SAW) technology offer unique advantages of remote wireless operation capability and zero power consumption. This article provides a comprehensive review of the working principles, important parameters, and the acoustic wave and materials types used in SAW-based UV detectors. The research and development status of these detectors are discussed and the most commonly used methods to optimize device performance are also summarized. Novel types of acoustic UV detectors based on thin film bulk acoustic resonators (FBARs) and Lamb wave resonators (LMRs) are briefly introduced. Finally, future development challenges are proposed and suggestions for future directions are provided to aid the development of this important research field.

Fabrication of monolithic diamond photodetector with microlenses

A monolithic diamond photodetector with microlenses is fabricated by etching microlens arrays (MLAs) on single crystal diamond surface and patterning tungsten electrode strips on the edge of these arrays. Firstly, compact MLAs are etched on half of diamond sample surface by thermal reflow method. Secondly, via magnetron sputtering technique, two sets of interdigitated tungsten electrodes are patterned on the sample surface, one set is on the edge of MLAs, the other set is on the planar area. The optoelectronic performances of photodetectors have been investigated and indicated that the photocurrent of microlens photodetector increases by 74.8 percent at 10 V under 220 nm UV light illumination by comparing with that in planar case. Simulations of photodetectors' electrical and optical properties have been carried out, illustrating an improvement of charge collection ability and light absorption efficiency in microlens case. Furthermore, the present device structure can be extended to other semiconductor photodetectors.