title: Fast Photoresponse and Long Lifetime UV Photodetectors and Field Emitters Based on ZnO/Ultrananocrystalline Diamond Films.
abstract: We have designed photodetectors and UV field emitters based on a combination of ZnO nanowires/nanorods (ZNRs) and bilayer diamond films in a metal-semiconductor-metal (MSM) structure. The ZNRs were fabricated on different diamond films and systematic investigations showed an ultra-high photoconductive response from ZNRs prepared on ultrananocrystalline diamond (UNCD) operating at a lower voltage of 2 V. We found that the ZNRs/UNCD photodetector (PD) has improved field emission properties and a reduced turn-on field of 2.9 V μm(-1) with the highest electron field emission (EFE) by simply illuminating the sample with ultraviolet (UV) light. The photoresponse (Iphoto /Idark ) behavior of the ZNRs/UNCD PD exhibits a much higher photoresponse (912) than bare ZNRs (229), ZNRs/nanocrystalline diamond (NCD; 518), and ZNRs/microcrystalline diamond (MCD; 325) under illumination at λ=365 nm. A photodetector with UNCD films offers superior stability and a longer lifetime compared with carbon materials and bare ZNRs. The lifetime stability of the ZNRs/UNCD-based device is about 410 min, which is markedly superior to devices that use bare ZNRs (92 min). The ZNRs/UNCD PD possesses excellent photoresponse properties with improved lifetime and stability; in addition, ZNRs/UNCD-based UV emitters have great potential for applications such as cathodes in flat-panel displays and microplasma display devices.
authors.affiliation: Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (Republic of China).
authors.forename: Adhimoorthy
authors.initials: A
authors.lastname: Saravanan
authors.affiliation: Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (Republic of China). huangbr@mail.ntust.edu.tw.
authors.forename: Bohr-Ran
authors.initials: BR
authors.lastname: Huang
authors.affiliation: Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (Republic of China).
authors.forename: Jun-Cheng
authors.initials: JC
authors.lastname: Lin
authors.affiliation: Boston University, Department of Electrical and Computer Engineering, Boston, (United States).
authors.forename: Gerd
authors.initials: G
authors.lastname: Keiser
authors.affiliation: Department of Physics, Tamkang University, Tamsui 251, Taiwan (Republic of China). inanlin@mail.tku.edu.tw.
authors.forename: I-Nan
authors.initials: IN
authors.lastname: Lin
keywords: UV field emitters; UV photodetectors; diamond films; lithography; nanostructures; photochemistry