ZnO 1D nanostructures designed by combining atomic layer deposition and electrospinning for UV sensor applications

Abstract

We explored for the first time the ability of a three-dimensional polyacrylonitrile/ZnO material prepared by a low-cost and scalable synthesis method based on the combination of electrospinning and atomic layer deposition (ALD) as a new material with a large surface area to enhance the performance of UV photodetection. The UV photoresponse current was enhanced by a factor of 250 compared to a flat electrode. In addition an increase by a factor of 1.3 of the recovery time has been observed which is negligible versus the huge amount of current enhancement. The greatly improved performance and the good stability of these nanostructured electrodes induce exciting materials for use in UV sensor applications. A IntroductionUV photodetection has been widely studied in the last few years 1-10 due to its large civil and military application elds such as secure space-to-space communications, pollution monitoring, water sterilization, and ame sensing. The semiconductor based UV photodetection process is a simple physical phenomenon based on electron-hole generation into a semiconductor under photon shelling. Basically when a photon with energy larger than the one of the semiconductor band-gap is absorbed, an electron-hole pair is produced. This induces a change of the electrical conductivity properties of the semiconductor. Low band gap energy semiconductors have been widely used for UV photodetection, especially the Si-based photodetectors (E g ¼ 1.1 eV). Despite both their high sensitivity and quick response advantages, low E g UV photodetectors are sensitive to low energy photons (visible and infrared), and thus, they require the insertion of protection lters to avoid signal/ noise related to those low electron energies. Moreover an ultrahigh vacuum and a very high voltage supply were required. 11 The disadvantages of the low E g based photodetectors disappear in the high band gap semiconductors. Moreover, wide-band gap materials are both chemically and thermally stable which is an advantage for devices operating in harsh environments. [12][13][14] Among the high band gap semiconductor category, ZnO is one of the most widely used semiconductors for UV photodetection due to its high chemical stability, low cost, and large band gap of 3.37 eV at room temperature. Mollow et al. reported the rst UV photoresponse in ZnO lms in 1940. 15 Since then, many complex ZnO-based photodetectors with high performance have been reported, such as p-n junction, p-i-n junction and Schottky junction. 3,16-23 ZnO UV sensors have been prepared using different deposition techniques such as Metal Organic Chemical Vapor Phase Deposition (MOCVD), 24,25 laser assisted molecular beam deposition (LAMBD), 26 radio frequency (RF) magnetron sputtering, 27-29 atomic-layer deposition (ALD) 30 and molecular beam epitaxy (MBE). 31,32 Moreover different electrode types such as Au, Ag, Pt, Ni, Pd, Cr, Al, and Ru have been elaborated and their performances have been investigated. Nanostructured ZnO for UV detection was also investigated. They show promisi...

Porosity-induced full-range visible-light photodetection via ultrahigh broadband antireflection in ZnO nanowires

“…ZnO can be easily synthesized in various 1D nanostructures [8][9][10][11][12] including nanowires (NWs), 13 nanotubes 14 and nanorods; 15 these structures have also shown promise in various nanoscale electronic and photonic devices, 16 such as photovoltaic cells, 17 light-emitting diodes, 18 gas sensors, 19 piezoelectric nanogenerators 20 and photodetectors. [21][22][23][24][25][26][27] However, with regard to photodetection, ZnO is only considered as a good material for UV photodetection 21,[23][24][25][26][27] owing to its wide band gap, and only a few studies have enabled ZnO to achieve limited visible light photodetection through doping or heterojunction structures. 22,28,29 This study is the first to demonstrate a new mechanism for obtaining a porosity-induced graded refractive index, which results in enhanced broadband antireflection properties, can extend the inherent properties of a 1D material, for example, the wide band gap of ZnO in this case, and can modify the material to enable improved visible-light photodetection over the entire visible-light regime.…”

Design of CoFe2O4/Co3O4 nanofibers with tunable morphology by Electrospinning

“…Any excess of Co reacts with the oxygen to form the stable form of Co 3 O 4 . The grain size was calculated by the Debye-Scherrer relationship [12,23]. As shown in Table 2, the grain size of CoFe 2 0 4 increases from 7.86 nm to 15.58 nm and the grain size of Co 3 0 4 decreases from 15.74 nm to 7.87 nm when the wt ratio Co/Fe increases.…”

“…In particular, nanofibers produced by Electrospinning, an effective and simple technique, have attracted considerable interest in recent years. [10][11][12] In fact, these nanofibers exhibit a very large surface area to volume ratio, flexibility in surface functionalities and mechanical characteristics more advanced than larger linear fibers [13].…”

Atomic layer deposition of biobased nanostructured interfaces for energy, environmental and health applications

“…Also at the nanoscale, quantum confinement effects can become much more important in determining the materials properties and characteristics, leading to novel optical, electrical and magnetic behaviors. These properties allow great impacts in electronics, medicine, energy harvesting [2][3][4], sensors [5] and other fields [6][7][8].…”