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Dascalescu I, Palade C, Slav A, Stavarache I, Cojocaru O, Teodorescu VS, Maraloiu VA, Lepadatu AM, Ciurea ML, Stoica T. Enhancing SiGeSn nanocrystals SWIR photosensing by high passivation in nanocrystalline HfO 2 matrix. Sci Rep 2024; 14:3532. [PMID: 38347024 PMCID: PMC10861535 DOI: 10.1038/s41598-024-53845-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 02/06/2024] [Indexed: 02/15/2024] Open
Abstract
SiGeSn nanocrystals (NCs) in oxides are of considerable interest for photo-effect applications due to the fine-tuning of the optical bandgap by quantum confinement in NCs. We present a detailed study regarding the silicon germanium tin (SiGeSn) NCs embedded in a nanocrystalline hafnium oxide (HfO2) matrix fabricated by using magnetron co-sputtering deposition at room temperature and rapid thermal annealing (RTA). The NCs were formed at temperatures in the range of 500-800 °C. RTA was performed to obtain SiGeSn NCs with surfaces passivated by the embedding HfO2 matrix. The formation of NCs and β-Sn segregation were discussed in relation to the deposition and processing conditions by employing HRTEM, XRD and Raman spectroscopy studies. The spectral photosensitivity exhibited up to 2000 nm in short-wavelength infrared (SWIR) depending on the Sn composition was obtained. Comparing to similar results on GeSn NCs in SiO2 matrix, the addition of Si offers a better thermal stability of SiGeSn NCs, while the use of HfO2 matrix results in better passivation of NCs increasing the SWIR photosensitivity at room temperature. These results suggest that SiGeSn NCs embedded in an HfO2 matrix are a promising material for SWIR optoelectronic devices.
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Affiliation(s)
- Ioana Dascalescu
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania
| | - Catalin Palade
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania
| | - Adrian Slav
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania
| | - Ionel Stavarache
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania
| | - Ovidiu Cojocaru
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania
| | - Valentin Serban Teodorescu
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania
- Academy of Romanian Scientists, 54 Splaiul Independentei, 050094, Bucharest, Romania
| | | | - Ana-Maria Lepadatu
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania.
| | - Magdalena Lidia Ciurea
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania.
- Academy of Romanian Scientists, 54 Splaiul Independentei, 050094, Bucharest, Romania.
| | - Toma Stoica
- National Institute of Materials Physics, 405A Atomistilor Street, 077125, Magurele, Romania.
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Yoo JH, Park WJ, Kim SW, Lee GR, Kim JH, Lee JH, Uhm SH, Lee HC. Preparation of Remote Plasma Atomic Layer-Deposited HfO 2 Thin Films with High Charge Trapping Densities and Their Application in Nonvolatile Memory Devices. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:nano13111785. [PMID: 37299688 DOI: 10.3390/nano13111785] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023]
Abstract
Optimization of equipment structure and process conditions is essential to obtain thin films with the required properties, such as film thickness, trapped charge density, leakage current, and memory characteristics, that ensure reliability of the corresponding device. In this study, we fabricated metal-insulator-semiconductor (MIS) structure capacitors using HfO2 thin films separately deposited by remote plasma (RP) atomic layer deposition (ALD) and direct-plasma (DP) ALD and determined the optimal process temperature by measuring the leakage current and breakdown strength as functions of process temperature. Additionally, we analyzed the effects of the plasma application method on the charge trapping properties of HfO2 thin films and properties of the interface between Si and HfO2. Subsequently, we synthesized charge-trapping memory (CTM) devices utilizing the deposited thin films as charge-trapping layers (CTLs) and evaluated their memory properties. The results indicated excellent memory window characteristics of the RP-HfO2 MIS capacitors compared to those of the DP-HfO2 MIS capacitors. Moreover, the memory characteristics of the RP-HfO2 CTM devices were outstanding as compared to those of the DP-HfO2 CTM devices. In conclusion, the methodology proposed herein can be useful for future implementations of multiple levels of charge-storage nonvolatile memories or synaptic devices that require many states.
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Affiliation(s)
- Jae-Hoon Yoo
- Department of Advanced Materials Engineering, Tech University of Korea, Siheung 15073, Republic of Korea
| | - Won-Ji Park
- Department of Advanced Materials Engineering, Tech University of Korea, Siheung 15073, Republic of Korea
| | - So-Won Kim
- Department of Advanced Materials Engineering, Tech University of Korea, Siheung 15073, Republic of Korea
| | - Ga-Ram Lee
- Department of Advanced Materials Engineering, Tech University of Korea, Siheung 15073, Republic of Korea
| | - Jong-Hwan Kim
- Department of Advanced Materials Engineering, Tech University of Korea, Siheung 15073, Republic of Korea
- EN2CORE Technology Inc., Daejeon 18469, Republic of Korea
| | - Joung-Ho Lee
- Korea Evaluation Institute of Industrial Technology, Seoul 06152, Republic of Korea
| | - Sae-Hoon Uhm
- EN2CORE Technology Inc., Daejeon 18469, Republic of Korea
| | - Hee-Chul Lee
- Department of Advanced Materials Engineering, Tech University of Korea, Siheung 15073, Republic of Korea
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Yu X, Ma Z, Shen Z, Li W, Chen K, Xu J, Xu L. 3D NAND Flash Memory Based on Double-Layer NC-Si Floating Gate with High Density of Multilevel Storage. NANOMATERIALS 2022; 12:nano12142459. [PMID: 35889681 PMCID: PMC9318664 DOI: 10.3390/nano12142459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/12/2022] [Accepted: 07/12/2022] [Indexed: 02/05/2023]
Abstract
As a strong candidate for computing in memory, 3D NAND flash memory has attracted great attention due to the high computing efficiency, which outperforms the conventional von-Neumann architecture. To ensure 3D NAND flash memory is truly integrated in the computing in a memory chip, a new candidate with high density and a large on/off current ratio is now urgently needed. Here, we first report that 3D NAND flash memory with a high density of multilevel storage can be realized in a double-layered Si quantum dot floating-gate MOS structure. The largest capacitance–voltage (C-V) memory window of 6.6 V is twice as much as that of the device with single-layer nc-Si quantum dots. Furthermore, the stable memory window of 5.5 V can be kept after the retention time of 105 s. The obvious conductance–voltage (G-V) peaks related to the charging process can be observed, which further confirms that the multilevel storage can be realized in double-layer Si quantum dots. Moreover, the on/off ratio of 3D NAND flash memory with a nc-Si floating gate can reach 104, displaying the characteristic of a depletion working mode of an N-type channel. The memory window of 3 V can be maintained after 105 P/E cycles. The programming and erasing speed can arrive at 100 µs under the bias of +7 V and −7 V. Our introduction of double-layer Si quantum dots in 3D NAND float gating memory supplies a new way to the realization of computing in memory.
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Affiliation(s)
- Xinyue Yu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
| | - Zhongyuan Ma
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
- Correspondence:
| | - Zixiao Shen
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
| | - Wei Li
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
| | - Kunji Chen
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
| | - Jun Xu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
| | - Ling Xu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China; (X.Y.); (Z.S.); (W.L.); (K.C.); (J.X.); (L.X.)
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, Nanjing University, Nanjing 210093, China
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Abstract
Group IV quantum dots (QDs) in HfO2 are attractive for non-volatile memories (NVMs) due to complementary metal-oxide semiconductor (CMOS) compatibility. Besides the role of charge storage centers, SiGeSn QDs have the advantage of a low thermal budget for formation, because Sn presence decreases crystallization temperature, while Si ensures higher thermal stability. In this paper, we prepare MOS capacitors based on 3-layer stacks of gate HfO2/floating gate of SiGeSn QDs in HfO2/tunnel HfO2/p-Si obtained by magnetron sputtering deposition followed by rapid thermal annealing (RTA) for nanocrystallization. Crystalline structure, morphology, and composition studies by cross-section transmission electron microscopy and X-ray diffraction correlated with Raman spectroscopy and C–V measurements are carried out for understanding RTA temperature effects on charge storage behavior. 3-layer morphology and Sn content trends with RTA temperature are explained by the strongly temperature-dependent Sn segregation and diffusion processes. We show that the memory properties measured on Al/3-layer stack/p-Si/Al capacitors are controlled by SiGeSn-related trapping states (deep electronic levels) and low-ordering clusters for RTA at 325–450 °C, and by crystalline SiGeSn QDs for 520 and 530 °C RTA. Specific to the structures annealed at 520 and 530 °C is the formation of two kinds of crystalline SiGeSn QDs, i.e., QDs with low Sn content (2 at.%) that are positioned inside the floating gate, and QDs with high Sn content (up to 12.5 at.%) located at the interface of floating gate with adjacent HfO2 layers. The presence of Sn in the SiGe intermediate layer decreases the SiGe crystallization temperature and induces the easier crystallization of the diamond structure in comparison with 3-layer stacks with Ge-HfO2 intermediate layer. High frequency-independent memory windows of 3–4 V and stored electron densities of 1–2 × 1013 electrons/cm2 are achieved.
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Impact of the Spectral Composition of Kilovoltage X-rays on High-Z Nanoparticle-Assisted Dose Enhancement. Int J Mol Sci 2021; 22:ijms22116030. [PMID: 34199667 PMCID: PMC8199749 DOI: 10.3390/ijms22116030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 05/23/2021] [Accepted: 05/27/2021] [Indexed: 01/01/2023] Open
Abstract
Nanoparticles (NPs) with a high atomic number (Z) are promising radiosensitizers for cancer therapy. However, the dependence of their efficacy on irradiation conditions is still unclear. In the present work, 11 different metal and metal oxide NPs (from Cu (ZCu = 29) to Bi2O3 (ZBi = 83)) were studied in terms of their ability to enhance the absorbed dose in combination with 237 X-ray spectra generated at a 30–300 kVp voltage using various filtration systems and anode materials. Among the studied high-Z NP materials, gold was the absolute leader by a dose enhancement factor (DEF; up to 2.51), while HfO2 and Ta2O5 were the most versatile because of the largest high-DEF region in coordinates U (voltage) and Eeff (effective energy). Several impacts of the X-ray spectral composition have been noted, as follows: (1) there are radiation sources that correspond to extremely low DEFs for all of the studied NPs, (2) NPs with a lower Z in some cases can equal or overcome by the DEF value the high-Z NPs, and (3) the change in the X-ray spectrum caused by a beam passing through the matter can significantly affect the DEF. All of these findings indicate the important role of carefully planning radiation exposure in the presence of high-Z NPs.
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Dragoman M, Dinescu A, Dragoman D, Palade C, Moldovan A, Dinescu M, Teodorescu VS, Ciurea ML. Wafer-scale graphene-ferroelectric HfO 2/Ge-HfO 2/HfO 2 transistors acting as three-terminal memristors. NANOTECHNOLOGY 2020; 31:495207. [PMID: 32946424 DOI: 10.1088/1361-6528/abb2bf] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this paper we report a set of experiments at the wafer level regarding field-effect transistors with a graphene monolayer channel transferred on the ferroelectric HfO2/Ge-HfO2/HfO2 three-layer structure. This kind of transistor has a switching ratio of 103 between on and off states due to the bandgap in graphene induced by the ferroelectric structure. Both top and back gates effectively control the carriers' charge flow in graphene. The transistor acts as a three-terminal memristor, termed a memtransistor, with applications in neuromorphic computation.
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Affiliation(s)
- M Dragoman
- National Institute for Research and Development in Microtechnology (IMT), Str. Erou Iancu Nicolae 126 A, Voluntari 077190, Romania
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