Tail-states induced appearance of conductor‑like behaviour in zinc‑tin‑oxide photo‑thinfilm transistors under sub-bandgap light excitation

2021 ◽  
Author(s):  
Soumen Dhara ◽  
Kham Niang ◽  
Andrew Flewitt ◽  
Arokia Nathan ◽  
Stephen Lynch
Keyword(s):  
Tin Oxide ◽  
Dark Current ◽  
Direct Evidence ◽  
Uv Light ◽  
Amorphous Structure ◽  
Persistent Photoconductivity ◽  
Current Analysis ◽  
Current Ratio ◽  
Zinc Tin Oxide ◽  
Light Excitation

Abstract We report on a strong persistent photoconductivity (PPC) induced appearance of conductor‑like behaviour in zinc-tin-oxide (ZTO) photo-thinfilm transistors (TFT). The active ZTO channel layer was prepared by remote-plasma reactive sputtering and possesses an amorphous structure. Under sub-bandgap excitation of ZTO with UV light, the photocurrent reaches as high as ~10-4 A (a photo-to-dark current ratio of ~107) and remains close to this high value after switching off the light. During this time, the ZTO TFT exhibits strong PPC with long-lasting recovery time, which leads the appearance of the conductor‑like behaviour in ZTO semiconductor. In the present case, the conductivity changes over six orders of magnitude, from ~10-7 to 0.92 Ω-1cm-1. After UV exposure, the ZTO compound can potentially remain in the conducting state for up to a month. The underlying physics of the observed PPC effect is investigated by studying defects (deep-states and tail-states) by employing a discharge current analysis (DCA) technique. Findings from the DCA study reveal direct evidence for the involvement of sub-gap tail-states of the ZTO in the strong PPC, while deep-states contribute to mild PPC.

scholarly journals Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Soumen Dhara ◽  
Kham M. Niang ◽  
Andrew J. Flewitt ◽  
Arokia Nathan ◽  
Stephen A. Lynch
Keyword(s):  
Tin Oxide ◽  
Direct Evidence ◽  
Uv Light ◽  
Optical Excitation ◽  
Amorphous Structure ◽  
Persistent Photoconductivity ◽  
Current Analysis ◽  
Current Ratio ◽  
Tail State ◽  
Zinc Tin Oxide

AbstractWe report on the appearance of a strong persistent photoconductivity (PPC) and conductor-like behaviour in zinc tin oxide (ZTO) thinfilm phototransistors. The active ZTO channel layer was prepared by remote plasma reactive sputtering and possesses an amorphous structure. Under sub-bandgap excitation of ZTO with UV light, the photocurrent reaches as high as ~ 10−4 A (a photo-to-dark current ratio of ~ 107) and remains close to this high value after switching off the light. During this time, the ZTO TFT exhibits strong PPC with long-lasting recovery time, which leads the appearance of the conductor-like behaviour in ZTO semiconductor. In the present case, the conductivity changes over six orders of magnitude, from ~ 10−7 to 0.92/Ω/cm. After UV exposure, the ZTO compound can potentially remain in the conducting state for up to a month. The underlying physics of the observed PPC effect is investigated by studying defects (deep states and tail states) by employing a discharge current analysis (DCA) technique. Findings from the DCA study reveal direct evidence for the involvement of sub-bandgap tail states of the ZTO in the strong PPC, while deep states contribute to mild PPC.

scholarly journals Ultra-Flexible Organic Solar Cell Based on Indium-Zinc-Tin Oxide Transparent Electrode for Power Source of Wearable Devices

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2633
Author(s):  
Jun Young Choi ◽  
In Pyo Park ◽  
Soo Won Heo
Keyword(s):  
Tin Oxide ◽  
Incident Angle ◽  
Flexible Substrate ◽  
Chemical Vapor ◽  
Transparent Electrode ◽  
Amorphous Structure ◽  
Wearable Devices ◽  
Power Source ◽  
Hole Transport ◽  
Zinc Tin Oxide

We have developed a novel structure of ultra-flexible organic photovoltaics (UFOPVs) for application as a power source for wearable devices with excellent biocompatibility and flexibility. Parylene was applied as an ultra-flexible substrate through chemical vapor deposition. Indium-zinc-tin oxide (IZTO) thin film was used as a transparent electrode. The sputtering target composed of 70 at.% In2O3-15 at.% ZnO-15 at.% SnO2 was used. It was fabricated at room temperature, using pulsed DC magnetron sputtering, with an amorphous structure. UFOPVs, in which a 1D grating pattern was introduced into the hole-transport and photoactive layers were fabricated, showed a 13.6% improvement (maximum power conversion efficiency (PCE): 8.35%) compared to the reference device, thereby minimizing reliance on the incident angle of the light. In addition, after 1000 compression/relaxation tests with a compression strain of 33%, the PCE of the UFOPVs maintained a maximum of 93.3% of their initial value.

scholarly journals Solar-Blind Photodetector Based on NaTaO3/TiO2 Composite Film with Enhanced Photoelectric Performance

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1178
Author(s):  
Min Zhang ◽  
Zhenjiang Li ◽  
Yunfei Zhao ◽  
Zhaofeng Wu ◽  
Jun Zhang ◽  
...  
Keyword(s):  
Response Time ◽  
Dark Current ◽  
High Performance ◽  
Uv Light ◽  
Fast Response ◽  
Current Ratio ◽  
Coated Glass Substrate ◽  
Ultraviolet Detectors ◽  
Photoelectric Performance ◽  
Solar Blind

In this study, ultraviolet detectors based on NaTaO3/TiO2 were fabricated with enhanced detection performance towards solar-blind (200–280 nm) light. A TiO2 seed layer was introduced and served as a buffer layer between the fluorine tin oxide (FTO)-coated glass substrate and the TiO2 film, which increased the adhesion between them. The periodic stability and photoelectric characteristics of the detectors were studied and analyzed. The detectors showed a high performance when illuminated by 265 nm and 254 nm UV light. At −15 V bias, the dark current of the detector was only 70 pA. Under the bias of −15 V and the illumination of 254 nm, the maximum photo-to-dark current ratio reached 20, and the response time was less than 300 ms. Moreover, the detector exhibited a fast response time and remained very stable after numerous testing cycles. These results demonstrate the potential application of NaTaO3/TiO2 composites in UV detection.

Photoresponses of Zinc Tin Oxide Thin-Film Transistor

2020 ◽  
Vol 20 (3) ◽  
pp. 1704-1708
Author(s):  
Wei Lun Huang ◽  
Chen-Chuan Yang ◽  
Sheng-Po Chang ◽  
Shoou-Jinn Chang
Keyword(s):  
Thin Film ◽  
Tin Oxide ◽  
Thin Film Transistor ◽  
Drain Current ◽  
Oxide Thin Film ◽  
Current Ratio ◽  
Uv Photodetector ◽  
Saturation Region ◽  
Zinc Tin Oxide ◽  
Sputtering System

In this study, the optical and electrical properties of a zinc tin oxide (ZTO) thin-film transistor (TFT) were investigated. The TFT was fabricated using ZTO as the active layer, which was deposited by a radio frequency magnetron sputtering system, to form an ultraviolet (UV) photodetector. The device has a threshold voltage of 0.48 V, field-effect mobility of 1.47 cm2/Vs in the saturation region, on/off drain current ratio of 2×106, and subthreshold swing of 0.45 V/decade in a dark environment. Moreover, as a UV photodetector, the device has a long photoresponse time, responsivity of 0.329 A/W, and rejection ratio of 3.19×104 at a gate voltage of -15 V under illumination of wavelength 300 nm.

scholarly journals In Situ Raman Investigation of TiO2 Nanotube Array-Based Ultraviolet Photodetectors: Effects of Nanotube Length

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1854
Author(s):  
Yanyu Ren ◽  
Xiumin Shi ◽  
Pengcheng Xia ◽  
Shuang Li ◽  
Mingyang Lv ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Dark Current ◽  
Uv Light ◽  
Tio2 Nanotube ◽  
Phonon Modes ◽  
Current Ratio ◽  
In Situ Raman Spectroscopy ◽  
In Situ Raman ◽  
532 Nm

TiO2 nanotube arrays (TNAs) with tube lengths of 4, 6, and 7 μm were prepared via two-step anodization. Thereafter, ultraviolet (UV) photodetectors (PDs) with Au/TiO2/Au structures were prepared using these TNAs with different tube lengths. The effects of TNA length and device area on the performance of the device were investigated using in situ Raman spectroscopy. The maximum laser/dark current ratio was achieved by using a TNA with a size of 1 × 1 cm2 and a length of 7 μm, under a 532 nm laser. In addition, when the device was irradiated with a higher energy laser (325 nm), the UV Raman spectrum was found to be more sensitive than the visible Raman spectrum. At 325 nm, the laser/dark current ratio was nearly 24 times higher than that under a 532 nm laser. Six phonon modes of anatase TNAs were observed, at 144, 199, 395, 514, and 635 cm−1, which were assigned to the Eg(1), Eg(2), B1g(1), A1g/B1g(2), and Eg(3) modes, respectively. The strong low-frequency band at 144 cm−1 was caused by the O-Ti-O bending vibration and is a characteristic band of anatase. The results show that the performance of TNA-based PDs is length-dependent. Surface-enhanced Raman scattering signals of 4-mercaptobenzoic acid (4-MBA) molecules were also observed on the TNA surface. This result indicates that the length-dependent performance may be derived from an increase in the specific surface area of the TNA. In addition, the strong absorption of UV light by the TNAs caused a blueshift of the Eg(1) mode.

Shape Effect of Zinc-Tin Oxide Nanostructures on Photodegradation of Methylene Blue and Rhodamine B under UV and Visible Light

2021 ◽  
Vol 4 (2) ◽  
pp. 1149-1161 ◽  
Author(s):  
Ana Rovisco ◽  
Rita Branquinho ◽  
Jonas Deuermeier ◽  
Tomás Freire ◽  
Elvira Fortunato ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Tin Oxide ◽  
Rhodamine B ◽  
Shape Effect ◽  
Oxide Nanostructures ◽  
Zinc Tin Oxide

Er3+/Yb3+ activated up-conversion luminescence of zinc-tin-oxide-based powders

2021 ◽  
Author(s):  
Tamara B. Ivetić ◽  
Yicong Ding ◽  
Miroslav Cvetinov ◽  
Jelena Petrović ◽  
Olivera R. Klisurić ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Zinc Tin Oxide

Highly efficient green-emitting phosphor Sr4Al14O25:Ce,Tb with low thermal quenching and wide color gamut upon UV-light excitation for backlighting display applications

2020 ◽  
Author(s):  
Haoran Li ◽  
Yujun Liang ◽  
Shiqi Liu ◽  
Weilun Zhang ◽  
Yanying Bi ◽  
...  
Keyword(s):  
Performance Enhancement ◽  
Uv Light ◽  
Thermal Quenching ◽  
High Response ◽  
Color Gamut ◽  
Ultraviolet Excitation ◽  
Highly Efficient ◽  
Near Ultraviolet ◽  
Wide Color Gamut ◽  
Light Excitation

Highly-efficient and stable inorganic phosphors with high response to near-ultraviolet excitation are essential to the performance enhancement of the phosphor converted backlighting devices. Herein, highly-efficient green-emitting phosphors Sr4Al14O25:Ce,Tb (SAO:Ce3+,Tb3+) with...

scholarly journals Violet-light stimulated synaptic and learning functions in a zinc–tin oxide photoelectric transistor for neuromorphic computation

RSC Advances ◽  
2020 ◽  
Vol 10 (70) ◽  
pp. 42682-42687
Author(s):  
Ting-Ruei Lin ◽  
Li-Chung Shih ◽  
Po-Jen Cheng ◽  
Kuan-Ting Chen ◽  
Jen-Sue Chen
Keyword(s):  
Thin Film ◽  
Tin Oxide ◽  
Thin Film Transistor ◽  
Violet Light ◽  
Learning Functions ◽  
Zinc Tin Oxide

Photonic potentiation and electric depression are realized in a ZTO thin film transistor for the application in neuromorphic computation.

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