Few-layer graphene/ZnO nanowires based high performance UV photodetector

Abstract

A graphene and zinc oxide nanowires (G/ZnO NWs) based ultraviolet (UV) photodetector presents excellent responsivity and photocurrent gain with detectivity. Graphene due to higher charge carrier transport mobility induces faster response to UV illumination at the interface between ZnO and graphene with improved response and decay times as compared to a ZnO NWs device alone. A linear increase is revealed for both the responsivity and photocurrent gain of the G/ZnO NWs device with the applied bias. These results suggest that the G/ZnO NWs device exhibits great promise for highly efficient UV photodetectors.

Fabrication of flexible ultraviolet photodetectors using an all-spray-coating process

“…24 The decay time constant τ 1 /τ 2 value of the measured device was 8.9/2.0 s. This result is comparable to the reported values (2.16-260 s/2.7-24.55 s) of Ga 2 O 3 , WO 3 , and ZnO. [25][26][27] The responsivity and response time of the devices are mainly related to the number of oxygen vacancies. The larger absence of oxygen vacancies leads to high photocurrent/dark-current ratio and fast recovery time due to the rapid transfer of photo-generated holes in the metal oxide semiconductor channel to …”

Nanoarchitechtonics of Visible‐Blind Ultraviolet Photodetector Materials: Critical Features and Nano‐Microfabrication

“…Wide bandgap semiconductors have been investigated in many recent studies to understand the fundamental process and enhancing the response to the UV light. [9,15,25b,40] The photoresponse characteristics of nanostructured devices are significantly influenced by a number of factors, such as the concentration of defects,[2d,3c] crystallographic orientation, bandgap, grain size,[1b,2d] and processing condition . These factors significantly influence the photoresponse behaviors explaining the large variation in performance previously reported by various groups for similar materials.…”

“…Low‐dimensional materials are usually classified into 0D,[19b,20] 1D,[2b,21] and 2D . Quantum dots (QDs), nanotubes, nanowires, nanorods, nanobelts,[22a,27] core/shell structures, nanostructure arrays,[19a,29] epitaxial film, and heterostructures are regarded as the future building blocks of visible‐blind UV photodetectors. Compared to traditional thin‐film and bulk materials, low‐dimensional nanostructured UV photodetectors are usually characterized by higher responsivity and photoconductivity gain,[1c,31] due to their high surface‐area‐to‐volume ratios and the nanoscale confined carrier transport kinetics.…”

“…Compared to traditional thin‐film and bulk materials, low‐dimensional nanostructured UV photodetectors are usually characterized by higher responsivity and photoconductivity gain,[1c,31] due to their high surface‐area‐to‐volume ratios and the nanoscale confined carrier transport kinetics. [3c,9,25b,32] The large surface‐to‐volume ratio significantly increases the number of surface trap states that can prolong the photocarrier lifetime by delaying the electron‐hole recombination process. [1b,3c,9] In fact, the photoexcited carriers can be trapped by surface trap states and in that case their decay dynamics is dominated by the escape time from the traps .…”

“…The latter has been shown to be a dominant feature resulting in significant variation in the UV light response of quasi‐identical nanomaterials. [9,25b,38] For instance, ZnO nanowires are usually reported to achieve orders of magnitude higher responsivity and detectivity than nanothin ZnO films. Similarly, ultraporous nanoparticle networks have shown thousand folds higher photo to dark‐current ratios than more densely arranged ZnO nanoparticle layers resulting in among the highest detectivity reported for such 0D materials.…”