المؤلفون: Kim, Hyunseok, Liu, Yunpeng, Lu, Kuangye, Chang, Celesta S., Qiao, Kuan, Kim, Ki Seok, Park, Bo-In, Jeong, Junseok, Zhu, Menglin, Suh, Jun Min, Baek, Yongmin, Ji, You Jin, Kang, Sungsu, Lee, Sangho, Han, Ne Myo, Kim, Chansoo, Choi, Chanyeol, Zhang, Xinyuan, Wang, Haozhe, Kong, Lingping, Park, Jungwon, Lee, Kyusang, Yeom, Geun Young, Kim, Sungkyu, Hwang, Jinwoo, Kong, Jing, Bae, Sang-Hoon, Kong, Wei, Kim, Jeehwan

مصطلحات موضوعية: Physics - Applied Physics, Condensed Matter - Materials Science

الوصف: Freestanding single-crystalline membranes are an important building block for functional electronics. Especially, compounds semiconductor membranes such as III-N and III-V offer great opportunities for optoelectronics, high-power electronics, and high-speed computing. Despite huge efforts to produce such membranes by detaching epitaxial layers from donor wafers, however, it is still challenging to harvest epitaxial layers using practical processes. Here, we demonstrate a method to grow and harvest multiple epitaxial membranes with extremely high throughput at the wafer scale. For this, 2D materials are directly formed on III-N and III-V substrates in epitaxy systems, which enables an advanced remote epitaxy scheme comprised of multiple alternating layers of 2D materials and epitaxial layers that can be formed by a single epitaxy run. Each epilayer in the multi-stack structure is then harvested by layer-by-layer peeling, producing multiple freestanding membranes with unprecedented throughput from a single wafer. Because 2D materials allow peeling at the interface without damaging the epilayer or the substrate, wafers can be reused for subsequent membrane production. Therefore, this work represents a meaningful step toward high-throughput and low-cost production of single-crystal membranes that can be heterointegrated.

الوصول الحر: http://arxiv.org/abs/2204.08002Test

المؤلفون: Ji, Jongho, Yang, Jeong Yong, Lee, Sangho, Kim, Seokgi, Yeom, Min Jae, Lee, Gyuhyung, Shin, Heechang, Bae, Sang-Hoon, Ahn, Jong-Hyun, Kim, Sungkyu, Kim, Jeehwan, Yoo, Geonwook, Kum, Hyun S.

المصدر: Springer Nature

الوصف: Heterogeneous integration of dissimilar crystalline materials has recently attracted considerable attention due to its potential for high-performance multifunctional electronic and photonic devices. The conventional method for fabricating heterostructures is by heteroepitaxy, in which epitaxy is performed on crystallographically different materials. However, epitaxial limitations in monolithic growth of dissimilar materials prevent implementation of high quality heterostructures, such as complex-oxides on conventional semiconductor platforms (Si, III-V and III-N). In this work, we demonstrate gallium nitride (GaN) high-electron-mobility transistors with crystalline complex-oxide material enabled by heterogeneous integration through epitaxial lift-off and direct stacking. We successfully integrate high-κ complex-oxide SrTiO3 in freestanding membrane form with GaN heterostructure via a simple transfer process as the gate oxide. The fabricated device shows steep subthreshold swing close to the Boltzmann limit, along with negligible hysteresis and low dynamic on-resistance, indicating very low defect density between the SrTiO3 gate oxide and GaN heterostructure. Our results show that heterogeneous integration through direct material stacking is a promising route towards fabricating functional heterostructures not possible by conventional epitaxy.

وصف الملف: application/pdf

العلاقة: Communications Engineering; https://hdl.handle.net/1721.1/153555Test; Ji, J., Yang, J.Y., Lee, S. et al. Heterogeneous integration of high-k complex-oxide gate dielectrics on wide band-gap high-electron-mobility transistors. Commun Eng 3, 15 (2024).

الإتاحة: https://hdl.handle.net/1721.1/153555Test

المؤلفون: Kim, Ki Seok, Kang, Ji Eun, Chen, Peng, Kim, Sungkyu, Ji, Jongho, Yeom, Geun Young, Kim, Jeehwan, Kum, Hyun S.

المصدر: AIP Publishing

مصطلحات موضوعية: General Engineering, General Materials Science

الوصف: Epitaxial lift-off techniques, which aim to separate ultrathin single-crystalline epitaxial layers off of the substrate, are becoming increasingly important due to the need of lightweight and flexible devices for heterogeneously integrated ultracompact semiconductor platforms and bioelectronics. Remote epitaxy is a relatively newly discovered epitaxial lift-off technique that allows substrate-seeded epitaxial growth of ultrathin films through few layers of graphene. This universal epitaxial lift-off technique allows freestanding single-crystal membrane fabrication very quickly at low cost. However, the conventional method of remote epitaxy requires transfer of graphene grown on another substrate to the target single-crystalline substrate, which results in organic and metallic residues as well as macroscopic defects such as cracks and wrinkles, significantly reducing the yield of remote epitaxy. Here, we show that direct growth of thick graphene on the target single-crystalline substrate (SrTiO3 for this study) followed by atomic layer etching (ALE) of the graphene layers create a defect- and residue-free graphene surface for high yield remote epitaxy. We find that the ALE efficiently removes one atomic layer of graphene per cycle, while also clearing multi-dots (clumps of carbon atoms) that form during nucleation of the graphene layers. Our results show that direct-grown graphene on the desired substrate accompanied by ALE might potentially be an ideal pathway toward commercialization of remote epitaxy.

وصف الملف: application/pdf

العلاقة: APL Materials; https://hdl.handle.net/1721.1/153571Test; Kim, Ki Seok, Kang, Ji Eun, Chen, Peng, Kim, Sungkyu, Ji, Jongho et al. 2022. "Atomic layer-by-layer etching of graphene directly grown on SrTiO3 substrates for high-yield remote epitaxy and lift-off." APL Materials, 10 (4).

الإتاحة: https://hdl.handle.net/1721.1/153571Test

المؤلفون: Kim, Sungyeon, Lee, Wookhee, Ko, Kyungmin, Cho, Hanbin, Cho, Hoyeon, Jeon, Seonhwa, Jeong, Changwook, Kim, Sungkyu, Ding, Feng, Suh, Joonki

المساهمون: National Natural Science Foundation of China, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Ulsan National Institute of Science and Technology, Ministry of Science and ICT, South Korea

المصدر: Advanced Materials ; ISSN 0935-9648 1521-4095

الوصف: Following an initial nucleation stage at the flake level, atomically thin film growth of a van der Waals material is promoted by ultrafast lateral growth and prohibited vertical growth. To produce these highly anisotropic films, synthetic or post‐synthetic modifications are required, or even a combination of both, to ensure large‐area, pure‐phase, and low‐temperature deposition. A set of synthetic strategies is hereby presented to selectively produce wafer‐scale tin selenides, SnSe x (both x = 1 and 2), in the 2D forms. The 2D‐SnSe 2 films with tuneable thicknesses are directly grown via metal–organic chemical vapor deposition (MOCVD) at 200 °C, and they exhibit outstanding crystallinities and phase homogeneities and consistent film thickness across the entire wafer. This is enabled by excellent control of the volatile metal–organic precursors and decoupled dual‐temperature regimes for high‐temperature ligand cracking and low‐temperature growth. In contrast, SnSe, which intrinsically inhibited from 2D growth, is indirectly prepared by a thermally driven phase transition of an as‐grown 2D‐SnSe 2 film with all the benefits of the MOCVD technique. It is accompanied by the electronic n ‐type to p ‐type crossover at the wafer scale. These tailor‐made synthetic routes will accelerate the low‐thermal‐budget production of multiphase 2D materials in a reliable and scalable fashion.

الإتاحة: https://doi.org/10.1002/adma.202400800Test

المؤلفون: Oh, Jungyeop, Park, Seohak, Lee, Sang Hun, Kim, Sungkyu, Lee, Hyeonji, Lee, Changhyeon, Hong, Woonggi, Cha, Jun‐Hwe, Kang, Mingu, Jin, Jun Hyup, Im, Sung Gap, Kim, Min Ju, Choi, Sung‐Yool

المصدر: Advanced Science ; volume 11, issue 23 ; ISSN 2198-3844 2198-3844

الوصف: Electrolyte‐gated synaptic transistors (EGSTs) have attracted considerable attention as synaptic devices owing to their adjustable conductance, low power consumption, and multi‐state storage capabilities. To demonstrate high‐density EGST arrays, 2D materials are recommended owing to their excellent electrical properties and ultrathin profile. However, widespread implementation of 2D‐based EGSTs has challenges in achieving large‐area channel growth and finding compatible nanoscale solid electrolytes. This study demonstrates large‐scale process‐compatible, all‐solid‐state EGSTs utilizing molybdenum disulfide (MoS 2 ) channels grown through chemical vapor deposition (CVD) and sub‐30 nm organic‐inorganic hybrid electrolyte polymers synthesized via initiated chemical vapor deposition (iCVD). The iCVD technique enables precise modulation of the hydroxyl group density in the hybrid matrix, allowing the modulation of proton conduction, resulting in adjustable synaptic performance. By leveraging the tunable iCVD‐based hybrid electrolyte, the fabricated EGSTs achieve remarkable attributes: a wide on/off ratio of 10 9 , state retention exceeding 10 3 , and linear conductance updates. Additionally, the device exhibits endurance surpassing 5 × 10 4 cycles, while maintaining a low energy consumption of 200 fJ/spike. To evaluate the practicality of these EGSTs, a subset of devices is employed in system‐level simulations of MNIST handwritten digit recognition, yielding a recognition rate of 93.2%.

الإتاحة: https://doi.org/10.1002/advs.202308847Test

المؤلفون: Lim, Byeong Min, Lee, Yu Min, Yoo, Chan Sik, Kim, Minjae, Kim, Seung Ju, Kim, Sungkyu, Yang, J. Joshua, Lee, Hong-Sub

المساهمون: National Research Foundation of Korea, Gyeonggi-do Regional Research Center

المصدر: ACS Nano ; volume 18, issue 8, page 6373-6386 ; ISSN 1936-0851 1936-086X

الإتاحة: https://doi.org/10.1021/acsnano.3c11325Test

المؤلفون: Lee, Woongkyu, Chen, Xianyu, Shao, Qing, Baik, Sung‐Il, Kim, Sungkyu, Seidman, David, Bedzyk, Michael, Dravid, Vinayak, Ketterson, John B., Medvedeva, Julia, Chang, Robert P. H., Grayson, Matthew A.

المصدر: Advanced Materials ; volume 35, issue 19 ; ISSN 0935-9648 1521-4095

الوصف: An unconventional “heteromorphic” superlattice (HSL) is realized, comprised of repeated layers of different materials with differing morphologies: semiconducting pc ‐In 2 O 3 layers interleaved with insulating a‐ MoO 3 layers. Originally proposed by Tsu in 1989, yet never fully realized, the high quality of the HSL heterostructure demonstrated here validates the intuition of Tsu, whereby the flexibility of the bond angle in the amorphous phase and the passivation effect of the oxide at interfacial bonds serve to create smooth, high‐mobility interfaces. The alternating amorphous layers prevent strain accumulation in the polycrystalline layers while suppressing defect propagation across the HSL. For the HSL with 7:7 nm layer thickness, the observed electron mobility of 71 cm 2 Vs ‐1 , matches that of the highest quality In 2 O 3 thin films. The atomic structure and electronic properties of crystalline In 2 O 3 /amorphous MoO 3 interfaces are verified using ab‐initio molecular dynamics simulations and hybrid functional calculations. This work generalizes the superlattice concept to an entirely new paradigm of morphological combinations.

الإتاحة: https://doi.org/10.1002/adma.202207927Test

المؤلفون: Ji, Jongho, Kwak, Hoe-Min, Yu, Jimyeong, Park, Sangwoo, Park, Jeong-Hwan, Kim, Hyunsoo, Kim, Seokgi, Kim, Sungkyu, Lee, Dong-Seon, Kum, Hyun S.

المصدر: Nano Convergence ; volume 10, issue 1 ; ISSN 2196-5404

مصطلحات موضوعية: General Engineering, General Materials Science

الإتاحة: https://doi.org/10.1186/s40580-023-00396-0Test

المؤلفون: Ji, Jongho, Kwak, Hoe-Min, Yu, Jimyeong, Park, Sangwoo, Park, Jeong-Hwan, Kim, Hyunsoo, Kim, Seokgi, Kim, Sungkyu, Lee, Dong-Seon, Kum, Hyun S.

المساهمون: National Research Foundation of Korea

المصدر: Nano Convergence ; volume 10, issue 1 ; ISSN 2196-5404

مصطلحات موضوعية: General Engineering, General Materials Science

الوصف: Remote epitaxy, which was discovered and reported in 2017, has seen a surge of interest in recent years. Although the technology seemed to be difficult to reproduce by other labs at first, remote epitaxy has come a long way and many groups are able to consistently reproduce the results with a wide range of material systems including III-V, III-N, wide band-gap semiconductors, complex-oxides, and even elementary semiconductors such as Ge. As with any nascent technology, there are critical parameters which must be carefully studied and understood to allow wide-spread adoption of the new technology. For remote epitaxy, the critical parameters are the (1) quality of two-dimensional (2D) materials, (2) transfer or growth of 2D materials on the substrate, (3) epitaxial growth method and condition. In this review, we will give an in-depth overview of the different types of 2D materials used for remote epitaxy reported thus far, and the importance of the growth and transfer method used for the 2D materials. Then, we will introduce the various growth methods for remote epitaxy and highlight the important points in growth condition for each growth method that enables successful epitaxial growth on 2D-coated single-crystalline substrates. We hope this review will give a focused overview of the 2D-material and substrate interaction at the sample preparation stage for remote epitaxy and during growth, which have not been covered in any other review to date. Graphical Abstract

الإتاحة: https://doi.org/10.1186/s40580-023-00368-4Test

المؤلفون: Oh, Jungyeop, Park, Seohak, Lee, Sang Hun, Kim, Sungkyu, Lee, Hyeonji, Lee, Changhyeon, Hong, Woonggi, Cha, Jun‐Hwe, Kang, Mingu, Jin, Jun Hyup, Im, Sung Gap, Kim, Min Ju, Choi, Sung‐Yool

المصدر: Advanced Science; 6/19/2024, Vol. 11 Issue 23, p1-11, 11p

مصطلحات موضوعية: CHEMICAL vapor deposition, ELECTROLYTES, SOLID electrolytes, ARTIFICIAL neural networks, MOLYBDENUM disulfide, SUPERIONIC conductors, TRANSISTORS

مستخلص: Electrolyte‐gated synaptic transistors (EGSTs) have attracted considerable attention as synaptic devices owing to their adjustable conductance, low power consumption, and multi‐state storage capabilities. To demonstrate high‐density EGST arrays, 2D materials are recommended owing to their excellent electrical properties and ultrathin profile. However, widespread implementation of 2D‐based EGSTs has challenges in achieving large‐area channel growth and finding compatible nanoscale solid electrolytes. This study demonstrates large‐scale process‐compatible, all‐solid‐state EGSTs utilizing molybdenum disulfide (MoS2) channels grown through chemical vapor deposition (CVD) and sub‐30 nm organic‐inorganic hybrid electrolyte polymers synthesized via initiated chemical vapor deposition (iCVD). The iCVD technique enables precise modulation of the hydroxyl group density in the hybrid matrix, allowing the modulation of proton conduction, resulting in adjustable synaptic performance. By leveraging the tunable iCVD‐based hybrid electrolyte, the fabricated EGSTs achieve remarkable attributes: a wide on/off ratio of 109, state retention exceeding 103, and linear conductance updates. Additionally, the device exhibits endurance surpassing 5 × 104 cycles, while maintaining a low energy consumption of 200 fJ/spike. To evaluate the practicality of these EGSTs, a subset of devices is employed in system‐level simulations of MNIST handwritten digit recognition, yielding a recognition rate of 93.2%. [ABSTRACT FROM AUTHOR]

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