Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector
Non-radiative energy transfer (NRET) from quantum dots (QDs) to monolayer MoS<sub>2</sub> has been shown to greatly enhance the photoresponsivity of the MoS<sub>2</sub> photodetector, lifting the limitations imposed by monolayer absorption thickness. Studies were often perfor...
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doaj-cf99a12205ed445397be5ec9ce53213d2020-11-25T03:06:34ZengMDPI AGNanomaterials2079-49912020-09-01101828182810.3390/nano10091828Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> PhotodetectorYung-Yu Lai0Yen-Wei Yeh1An-Jye Tzou2Yi-Yuan Chen3YewChung Sermon Wu4Yuh-Jen Cheng5Hao-Chung Kuo6Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, TaiwanResearch Center for Applied Sciences, Academia Sinica, Taipei 11529, TaiwanTaiwan Semiconductor Research Institute, National Applied Research Laboratories, Hsinchu 30078, TaiwanDepartment of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, TaiwanDepartment of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, TaiwanResearch Center for Applied Sciences, Academia Sinica, Taipei 11529, TaiwanDepartment of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 30010, TaiwanNon-radiative energy transfer (NRET) from quantum dots (QDs) to monolayer MoS<sub>2</sub> has been shown to greatly enhance the photoresponsivity of the MoS<sub>2</sub> photodetector, lifting the limitations imposed by monolayer absorption thickness. Studies were often performed on a photodetector with a channel length of only a few μm and an active area of a few μm<sup>2</sup>. Here, we demonstrate a QD sensitized monolayer MoS<sub>2</sub> photodetector with a large channel length of 40 μm and an active area of 0.13 mm<sup>2</sup>. The QD sensitizing coating greatly enhances photoresponsivity by 14-fold at 1.3 μW illumination power, as compared with a plain monolayer MoS<sub>2</sub> photodetector without QD coating. The photoresponsivity enhancement increases as QD coating density increases. However, QD coating also causes dark current to increase due to charge doping from QD on MoS<sub>2</sub>. At low QD density, the increase of photocurrent is much larger than the increase of dark current, resulting in a significant enhancement of the signal on/off ratio. As QD density increases, the increase of photocurrent becomes slower than the increase of dark current. As a result, photoresponsivity increases, but the on/off ratio decreases. This inverse dependence on QD density is an important factor to consider in the QD sensitized photodetector design.https://www.mdpi.com/2079-4991/10/9/1828molybdenum disulfidequantum dotsphotodetectorsnon-radiative energy transfer |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yung-Yu Lai Yen-Wei Yeh An-Jye Tzou Yi-Yuan Chen YewChung Sermon Wu Yuh-Jen Cheng Hao-Chung Kuo |
spellingShingle |
Yung-Yu Lai Yen-Wei Yeh An-Jye Tzou Yi-Yuan Chen YewChung Sermon Wu Yuh-Jen Cheng Hao-Chung Kuo Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector Nanomaterials molybdenum disulfide quantum dots photodetectors non-radiative energy transfer |
author_facet |
Yung-Yu Lai Yen-Wei Yeh An-Jye Tzou Yi-Yuan Chen YewChung Sermon Wu Yuh-Jen Cheng Hao-Chung Kuo |
author_sort |
Yung-Yu Lai |
title |
Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector |
title_short |
Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector |
title_full |
Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector |
title_fullStr |
Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector |
title_full_unstemmed |
Dependence of Photoresponsivity and On/Off Ratio on Quantum Dot Density in Quantum Dot Sensitized MoS<sub>2</sub> Photodetector |
title_sort |
dependence of photoresponsivity and on/off ratio on quantum dot density in quantum dot sensitized mos<sub>2</sub> photodetector |
publisher |
MDPI AG |
series |
Nanomaterials |
issn |
2079-4991 |
publishDate |
2020-09-01 |
description |
Non-radiative energy transfer (NRET) from quantum dots (QDs) to monolayer MoS<sub>2</sub> has been shown to greatly enhance the photoresponsivity of the MoS<sub>2</sub> photodetector, lifting the limitations imposed by monolayer absorption thickness. Studies were often performed on a photodetector with a channel length of only a few μm and an active area of a few μm<sup>2</sup>. Here, we demonstrate a QD sensitized monolayer MoS<sub>2</sub> photodetector with a large channel length of 40 μm and an active area of 0.13 mm<sup>2</sup>. The QD sensitizing coating greatly enhances photoresponsivity by 14-fold at 1.3 μW illumination power, as compared with a plain monolayer MoS<sub>2</sub> photodetector without QD coating. The photoresponsivity enhancement increases as QD coating density increases. However, QD coating also causes dark current to increase due to charge doping from QD on MoS<sub>2</sub>. At low QD density, the increase of photocurrent is much larger than the increase of dark current, resulting in a significant enhancement of the signal on/off ratio. As QD density increases, the increase of photocurrent becomes slower than the increase of dark current. As a result, photoresponsivity increases, but the on/off ratio decreases. This inverse dependence on QD density is an important factor to consider in the QD sensitized photodetector design. |
topic |
molybdenum disulfide quantum dots photodetectors non-radiative energy transfer |
url |
https://www.mdpi.com/2079-4991/10/9/1828 |
work_keys_str_mv |
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