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Kim SW, Kwon J, Lee JS, Kang BH, Lee SW, Jung DG, Lee JY, Han M, Kim OG, Saianand G, Jung D. An Organic/Inorganic Nanomaterial and Nanocrystal Quantum Dots-Based Multi-Level Resistive Memory Device. NANOMATERIALS 2021; 11:nano11113004. [PMID: 34835768 PMCID: PMC8620175 DOI: 10.3390/nano11113004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/05/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022]
Abstract
A cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dot (QD)-based multi-level memory device with the structure [ITO/PEDOT:PSS/QDs/ZnO/Al:Al2O3/QDs/Al] was fabricated via a spin-coating method used to deposit thin films. Two layers of QD thin films present in the device act as charge storage layers to form three distinct states. Zinc oxide (ZnO) and aluminum oxide (Al2O3) were added to prevent leakage. ZnO NPs provide orthogonality between the two QD layers, and a poly(3,4-ethylenedioxythio-phene): poly(styrenesulfonate) (PEDOT:PSS) thin film was formed for effective hole injection from the electrodes. The core/shell structure of the QDs provides the quantum well, which causes the trapping of injected charges. The resistance changes according to the charging and discharging of the QDs' trap site and, as a result, the current through the device also changes. There are two quantum wells, two current changes, and three stable states. The role of each thin film was confirmed through I-V curve analysis and the fabrication conditions of each thin film were optimized. The synthesized QDs and ZnO nanoparticles were evaluated via X-ray diffraction, transmission electron microscopy, and absorbance and photoluminescence spectroscopy. The measured write voltages of the fabricated device were at 1.8 and 2.4 V, and the erase voltages were -4.05 and -4.6 V. The on/off ratio at 0.5 V was 2.2 × 103. The proposed memory device showed retention characteristics of ≥100 h and maintained the initial write/erase voltage even after 200 iterative operations.
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Affiliation(s)
- Sae-Wan Kim
- Advanced Mechatronics R&D Group, Korea Institute of Industrial Technology (KITECH), Daegu 42994, Korea; (S.-W.K.); (J.K.); (D.G.J.); (J.-Y.L.)
| | - JinBeom Kwon
- Advanced Mechatronics R&D Group, Korea Institute of Industrial Technology (KITECH), Daegu 42994, Korea; (S.-W.K.); (J.K.); (D.G.J.); (J.-Y.L.)
| | - Jae-Sung Lee
- Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi 39253, Korea; (J.-S.L.); (B.-H.K.)
| | - Byoung-Ho Kang
- Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi 39253, Korea; (J.-S.L.); (B.-H.K.)
| | - Sang-Won Lee
- Daegu Technopark Daegu Smart Manufacturing Innovation Center, 46-17, Seongseogongdan-ro, Dalseogu, Daegu 42716, Korea;
| | - Dong Geon Jung
- Advanced Mechatronics R&D Group, Korea Institute of Industrial Technology (KITECH), Daegu 42994, Korea; (S.-W.K.); (J.K.); (D.G.J.); (J.-Y.L.)
| | - Jun-Yeop Lee
- Advanced Mechatronics R&D Group, Korea Institute of Industrial Technology (KITECH), Daegu 42994, Korea; (S.-W.K.); (J.K.); (D.G.J.); (J.-Y.L.)
| | - Maeum Han
- School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80, Daehak-ro, Buk-gu, Daegu 41566, Korea; (M.H.); (O.-G.K.)
| | - Ok-Geun Kim
- School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 80, Daehak-ro, Buk-gu, Daegu 41566, Korea; (M.H.); (O.-G.K.)
| | - Gopalan Saianand
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle, Callaghan, NSW 2308, Australia;
| | - Daewoong Jung
- Advanced Mechatronics R&D Group, Korea Institute of Industrial Technology (KITECH), Daegu 42994, Korea; (S.-W.K.); (J.K.); (D.G.J.); (J.-Y.L.)
- Correspondence:
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Kwon JB, Kim SW, Kang BH, Yeom SH, Lee WH, Kwon DH, Lee JS, Kang SW. Air-stable and ultrasensitive solution-cast SWIR photodetectors utilizing modified core/shell colloidal quantum dots. NANO CONVERGENCE 2020; 7:28. [PMID: 32803407 PMCID: PMC7429620 DOI: 10.1186/s40580-020-00238-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 07/16/2020] [Indexed: 06/11/2023]
Abstract
InGaAs-based photodetectors have been generally used for detection in the short-wave infrared (SWIR) region. However, the epitaxial process used to grow these materials is expensive; therefore, InGaAs-based photodetectors are limited to space exploration and military applications. Many researchers have expended considerable efforts to address the problem of SWIR photodetector development using lead sulfide (PbS) quantum dots (QDs). Along with their cost-efficient solution processability and flexible substrate compatibility, PbS QDs are highly interesting for the quantum-size-effect tunability of their bandgaps, spectral sensitivities, and wide absorption ranges. However, the performance of PbS QD-based SWIR photodetectors is limited owing to inefficient carrier transfer and low photo and thermal stabilities. In this study, a simple method is proposed to overcome these problems by incorporating CdS in PbS QD shells to provide efficient carrier transfer and enhance the long-term stability of SWIR photodetectors against oxidation. The SWIR photodetectors fabricated using thick-shell PbS/CdS QDs exhibited a high on/off (light/dark) ratio of 11.25 and a high detectivity of 4.0 × 1012 Jones, which represents a greater than 10 times improvement in these properties relative to those of PbS QDs. Moreover, the lifetimes of thick-shell PbS/CdS QD-based SWIR photodetectors were significantly improved owing to the self-passivation of QD surfaces.
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Affiliation(s)
- Jin-Beom Kwon
- School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 1370 Sankyuk-dong, Daegu, 702-701, Republic of Korea
| | - Sae-Wan Kim
- School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 1370 Sankyuk-dong, Daegu, 702-701, Republic of Korea
| | - Byoung-Ho Kang
- Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi, 39253, Republic of Korea
| | - Se-Hyuk Yeom
- Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi, 39253, Republic of Korea
| | - Wang-Hoon Lee
- Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi, 39253, Republic of Korea
| | - Dae-Hyuk Kwon
- Department of Electronic Engineering, Kyungil University, Hayang-up, 712-702, Gyeongsang buk-do, Republic of Korea
| | - Jae-Sung Lee
- Advanced Semiconductor Research Center, Gumi Electronics and Information Technology Research Institute (GERI), Gumi, 39253, Republic of Korea.
| | - Shin-Won Kang
- School of Electronics Engineering, College of IT Engineering, Kyungpook National University, 1370 Sankyuk-dong, Daegu, 702-701, Republic of Korea.
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