Effects of surface adsorbed oxygen, applied voltage, and temperature on UV photoresponse of ZnO nanorods

Abstract

The ultraviolet (UV) photoresponses of ZnO nanorods directly grown on and between two micro Au-electrodes by using electric-field-assisted wet chemical method are measured comprehensively under different conditions, including ambient environment, applied bias voltage, gate voltage and temperature. Experimental results indicate that the photoresponses of the ZnO nanorods can be modulated by surface oxygen adsorptions, applied voltages, as well as temperatures. A model taking into account both surface adsorbed oxygen and electron-hole activities inside ZnO nanorods is proposed. The enhancement effect of the bias voltage on photoresponse is also analyzed. Experimental results shows that the UV response time (to 63%) of ZnO nanorods in air and at 59 • C could be shortened from 34.8 s to 0.24 s with a bias of 4 V applied between anode and cathode.

The Optoelectrical Properties of Li: TiO2/p‐Si Photodiodes for Various Li Doping

“…The occurrence of this case with the doping can be attributed to the internal parameters, such as trap states and recombination centers within the optical bandgap due to doping, [64,65] rather than external factors such as the absorption and desorption of ionized oxygen or water www.advancedsciencenews.com www.pss-a.com molecules. [66,67] The Li-doped TiO 2 based photodiodes have two different rising regions that respond fast and subsequently slow to illumination. The fast response and the slow response are ascribed to the initial photogeneration of charges from band to band and the presence of traps, respectively.…”

Multifunctional Three-in-One Sensor on t-ZnO for Ultraviolet and VOC Sensing for Bioengineering Applications

“…By increasing the applied bias voltage, both the dark current and the photocurrent increased while the response time decreased [ 54 ]. This can be attributed to a stronger electric field, resulting in fast carrier travel.…”

Dual Light Temporal Coding Modes Enabled by Nanoparticle-Mediated Phototransistors via Gate Bias Modulation for Brain-Inspired Visual Perception

“…Under light illumination, the attached ionic oxygen (O 2 – ) on the ZnO NP surface tends to recombine with ionized oxygen vacancies, thereby leading to oxygen molecules desorption from the ZnO surface. This desorption process leaves an excess of electrons, increasing the ZnO NP conductivity. − Due to the slow recombination of ionized oxygen vacancies and photoelectrons (PPC effect) after light illumination, the molecular O 2 could be ionized by the photogenerated electrons, resulting in the ionic oxygen chemisorption to the ZnO surface (Figure c). Thus, both, the O 2 – desorption process and ionization reaction of neutral oxygen vacancies, would occur again while applying the second light spike (Figure d).…”