Publications

2026

1. In Prep.

   Ultraviolet electroluminescence from hexagonal boron nitride with in-situ carbon-incorporation by MOCVD

   Semi Im^‡, Seokho Moon^‡, Jawon Kim, Seung Eun Lee, Jaesub Song, Changuk Ji, Seonghyeon Pak, Kenji Watanabe, Takashi Taniguchi, and Jong Kyu Kim

   Manuscript in preparation (2026)
2. In Prep.

   In-situ heating electron microscopy of atomic grain boundary migration dynamics in monolayer MoS2 grain growth

   Chang-Won Choi, Min-Yeong Choi, Jinho Rhee, Seokho Moon, Jong Kyu Kim, Jungwon Park, Chel-Joo Kim, and Si-Young Choi

   Manuscript in preparation (2026)
3. In Prep.

   RF performance and radiation tolerance improvement in GaN-based HEMTs using extremely thin h-BN passivation layer and air spacer

   Sung-Jae Chang, Seokho Moon, Dong-Seok Kim, Junhyung Jeong, Hyun-Wook Jung, Jawon Kim, Semi Im, Jaesub Song, Changuk Ji, Seonghyeon Pak, Seong-Il Kim, Sang-Heung Lee, Ho-Kyun Ahn, Dong-Min Kang, Jong Kyu Kim, and Jong-Won Lim

   Manuscript in preparation (Submitted to IMS 2026) (2026)
4. In Prep.

   GaN membranes with controllable separation from the substrate via quasi van der Waals epitaxy on a commercial MOCVD system

   Hoe-Min Kwak, Hyeon-Tak Kwak, Seokho Moon, Dong-Han Kim, Inyong Hwang, Jeongwoon Kim, Changuk Ji, Hyung-Seok Lee, Rakjun Choi, Seungbae Yang, Hong-Sik Park, Jong Kyu Kim, Dong-Seon Lee, and Seong-Bum Bae

   Manuscript in preparation (2026)

2025

1. Nat. Mater.

   Wafer-scale AA-stacked hexagonal boron nitride grown on a GaN substrate

   Seokho Moon, Odongo Francis Ngome Okello, Adrien Rousseau, Chang-Won Choi, Youngjae Kim, Yunjae Park, Jiye Kim, Jaewon Kim, Minhyuk Kim, Pierre Valvin, Jaehee Cho, Kenji Watanabe, Takashi Taniguchi, Hu Young Jeong, Giorgia Fugallo, Wilfried Desrat, Feng Ding, JaeDong Lee, Bernard Gil, Guillaume Cassabois^*, Si-Young Choi^*, and Jong Kyu Kim^*

   Nature Materials 24, 843–851 (2025)

   Abs

   Featured in: Nature Materials — News & Views · Nature Synthesis — Research Highlight. Media coverage: Phys.org, EurekAlert!, AZoMaterials, Scienmag, and various Korean media outlets (전자신문, 지디넷코리아, 교수신문 등).

   The stacking sequence of two-dimensional hexagonal boron nitride (hBN) is a critical factor that determines its polytypes and its distinct physical properties. Although most hBN layers adopt the thermodynamically stable AA’ stacking sequence, achieving alternative stacking configurations has remained a long-standing challenge. Here we demonstrate the scalable synthesis of hBN featuring unprecedented AA stacking, where atomic monolayers align along the c axis without any translation or rotation. This previously considered thermodynamically unfavourable hBN polytype is achieved through epitaxial growth on a two-inch single-crystalline gallium nitride wafer, using a metal-organic chemical vapour deposition technique. Comprehensive structural and optical characterizations, complemented by theoretical modelling, evidence the formation of AA-stacked multilayer hBN and reveal that hBN nucleation on the vicinal gallium nitride surface drives the unidirectional alignment of layers. Here electron doping plays a central role in stabilizing the AA stacking configuration. Our findings provide further insights into the scalable synthesis of engineered hBN polytypes, characterized by unique properties such as large optical nonlinearity.

2. 2D Mater.

   Metal-organic chemical vapor deposition of hexagonal boron nitride: from high-quality growth to functional engineering

   Seokho Moon, Semi Im, Jawon Kim, Jaesub Song, Changuk Ji, Seonghyeon Pak, and Jong Kyu Kim^*

   2D Materials 12, 042006 (2025)

   Abs

   The rapid advancement of next-generation photonic and electronic technologies has placed hexagonal boron nitride (hBN) at the forefront of research on two-dimensional materials. Renowned for its deep-ultraviolet band-edge emission, exceptional dielectric properties, and ability to host quantum defects, hBN offers a versatile platform for a broad range of applications. However, realizing these capabilities on a wafer scale requires an appropriate synthesis technique that not only ensures high crystallinity but also provides precise functionalization control—a challenge effectively addressed by metal-organic chemical vapor deposition (MOCVD). This review highlights the evolution of MOCVD from a technique primarily focused on high-quality hBN epitaxy to a powerful tool for defect engineering, doping control, and stacking sequences. By enabling wafer-scale synthesis with tunable optical, electronic, and quantum functionalities, MOCVD-grown hBN is paving the way for transformative advancements in optoelectronics, quantum information science, and next-generation semiconductor technologies.

3. Prog. Quantum Electron.

   Quantum emitters based on hexagonal boron nitride for next-generation quantum technology

   Semi Im^‡, Seokho Moon^‡, Jawon Kim, Jaesub Song, Changuk Ji, Seonghyeon Pak, and Jong Kyu Kim^*

   Progress in Quantum Electronics 102, 100576 (2025)

   Abs

   Hexagonal boron nitride (h-BN), a wide-bandgap layered van der Waals material, has garnered significant attention due to its exceptional properties, making it a highly versatile material in various applications. In particular, recent studies have demonstrated that h-BN hosts stable quantum emitters over a broad spectral range at room temperature, positioning it as a compelling candidate for next generation quantum technology platforms. In this review, we present a comprehensive analysis of optically active defects in h-BN, focusing on their structural and optical properties. In addition, we discuss various defect generation methods and excitation techniques aimed at achieving efficient quantum emission. Furthermore, we highlight advances in integrating h-BN quantum emitters into device architectures, emphasizing their compatibility with photonic circuits and scalable quantum systems. The progress, challenges, and future outlook of h-BN-based quantum emitters as a transformative platform for next-generation quantum technologies are discussed.

4. Small

   Analog switching in hexagonal boron nitride memristors via multiple nano-filaments confinement

   Jaesub Song, Seokho Moon, Jinho Byun, Jiye Kim, Junyoung Choi, Hyunjeong Kwak, Inyong Hwang, Changuk Ji, Seyoung Kim, and Jong Kyu Kim^*

   Small 21, 2504507 (2025)

   Abs

   Memristors have emerged as a key building block for artificial neural networks (ANNs), offering energy efficiency and high scalability for hardware-based synaptic weight updates. As device miniaturization is crucial for enhancing memristor performance, hexagonal boron nitride (h-BN) stands out as a promising resistive switching medium due to its excellent insulating characteristics even at an atomically thin scale. However, conventional h-BN memristors suffer from abrupt switching behavior by uncontrollable filament formation, limiting their potential for ANN applications. Here, h-BN-based memristors exhibiting linear and symmetric analog switching by leveraging multiple nano-filament confinement is presented. The geometric confinement between suspended h-BN films and the apexes of GaN nano-cones facilitates analog switching behavior, reducing cycle-to-cycle variation and ensuring stable consecutive operations. Electrical analyses reveal that analog switching behavior originates from the controlled formation of multiple nano-filaments within the confined geometry. ANNs implemented with these nano-filaments confined to h-BN memristors exhibit highly linear and symmetric synaptic weight updates, enabling precise training with minimal accuracy degradation. This work establishes multiple nano-filament confinement as a universal design strategy for achieving reliable and linear analog switching in memristors, paving the way for advanced neuromorphic computing.

5. ACS Appl. Electron. Mater.

   Self-exfoliation in quasi-van der Waals epitaxy of III-nitrides on hexagonal boron nitride

   Peilong Yang, Seokho Moon, Semi Im, Jawon Kim, Jaesub Song, Changwook Ji, Seonghyeon Pak, Zhibiao Hao, Yi Luo, Changzheng Sun, Bing Xiong, Yanjun Han, Jian Wang, Hongtao Li, Lin Gan, Jong Kyu Kim, and Lai Wang^*

   ACS Applied Electronic Materials 7, 9380–9388 (2025)

   Abs

   Van der Waals (vdW) epitaxy offers a promising route for growing III-nitride semiconductors without traditional substrate constraints. Among its unique capabilities, spontaneous self-exfoliation—where grown layers automatically separate from substrates—could revolutionize device fabrication by eliminating complex removal processes. However, the underlying mechanisms controlling this phenomenon remain unclear, hindering reliable implementation. This study investigates the self-exfoliation in gallium nitride (GaN) films grown via metal–organic chemical vapor deposition (MOCVD) on hexagonal boron nitride (h-BN) templates and discovered that h-BN structural integrity determines exfoliation behavior. An optimized aluminum gallium nitride (AlGaN) buffer strategy was developed (910 °C, 15 min), which has been shown to protect the integrity of h-BN during subsequent growth. Comparing GaN film growth on as-grown versus transferred h-BN substrates revealed a critical distinction: self-exfoliation occurs exclusively on as-grown h-BN, while transferred h-BN is destroyed during growth, preventing separation. The driving mechanism involves thermal expansion differences that generate compressive stress exceeding h-BN’s weak interlayer bonding during cooling. Self-exfoliated films demonstrate exceptional strain relaxation (residual stress <0.05 GPa) and successful transfer to arbitrary substrates, enabling applications in flexible electronics, micro-LED displays, and heterogeneous integration.

6. Adv. Electron. Mater.

   Demonstration of GaN-based HEMTs using extremely thin h-BN passivation layer and air spacer for the RF performance improvement

   Sung-Jae Chang^*, Seokho Moon, Junhyung Jeong, Hyun-Wook Jung, Jawon Kim, Semi Im, Jaesub Song, Changuk Ji, Seonghyeon Pak, Il-Gyu Choi, Jong-Won Lim, and Jong Kyu Kim

   Advanced Electronic Materials 11, 2500638 (2025)

   Abs

   GaN-based high electron mobility transistors (HEMTs) is demonstrated using an extremely thin (≈ 5 nm) h-BN passivation layer and air spacer, for the first time. The h-BN passivation layer is grown by metal–organic chemical vapor deposition on top of the AlGaN barrier, followed by GaN-based HEMTs fabrication. To prohibit the loss and/or damage of the thin h-BN passivation layer, the SiN is deposited as a protection layer during the device fabrication. When the device fabrication is finalized, the SiN protection layer is removed by buffered oxide etchant, introducing the air spacer under the head of the T-gate electrode. The electrical properties of the GaN-based HEMTs applying h-BN passivation layer and air spacer are measured and compared to the h-BN/SiN passivated and conventional SiN passivated GaN-based HEMTs. The difference of the DC characteristics corresponding to the passivation layer in GaN-based HEMTs is negligible. However, compared to the conventional SiN passivated GaN-based HEMTs, the RF performance, such as current gain cut-off frequency and maximum oscillation frequency is improved by 50.3% and 68.5%, respectively, since the parasitic capacitances is reduced by the air spacer formation in GaN-based HEMTs using a thin h-BN passivation layer.

7. J. Appl. Phys.

   The heterostructure of hexagonal boron nitride with wurtzite III-nitrides for optoelectronic and electronic applications

   Jawon Kim^‡, Seokho Moon^‡, Semi Im, Jaesub Song, Changuk Ji, Seonghyeon Pak, and Jong Kyu Kim^*

   Journal of Applied Physics 137, 210902 (2025)

   Abs

   Semiconductor heterostructures are essential for advancing modern technology, facilitating the development of more efficient and powerful electronic and optoelectronic devices. Conventional heterostructures, formed through the covalent bonding or the ionic bonding of distinct materials at their atomic-scale interfaces, are inherently constrained by lattice matching, which restricts material selection and design flexibility. In contrast, heterostructures involving two-dimensional layered materials utilize van der Waals (vdW) forces for bonding, allowing for more versatile and flexible assembly of structurally dissimilar materials, offering new opportunities beyond traditional epitaxial approaches. In this review, we focus on hexagonal boron nitride (h-BN)/AlGaInN heterostructures, where AlGaInN—recognized for their excellent electronic and optical properties—is integrated with hexagonal boron nitride (h-BN), a 2D III-nitride material with a wide bandgap and exceptional thermal and chemical stability. We discuss fabrication strategies for achieving high-quality h-BN/AlGaInN heterostructures, their influence on optoelectronic performance, and the role of h-BN in enhancing device efficiency and facilitating vdW epitaxy for flexible electronics. Finally, we outline key challenges and future research directions, emphasizing the potential of 2D/3D III-nitride heterostructures for next-generation semiconductor technologies.

2024

1. Small

   Attojoule hexagonal boron nitride-based memristor for high-performance neuromorphic computing

   Jiye Kim, Jaesub Song, Hyunjoung Kwak, Chang-Won Choi, Kyungmi Noh, Seokho Moon, Hyeonwoong Hwang, Inyong Hwang, Hokyeong Jeong, Si-Young Choi, and Jong Kyu Kim^*

   Small 20, 2403737 (2024)

   Abs

   In next-generation neuromorphic computing applications, the primary challenge lies in achieving energy-efficient and reliable memristors while minimizing their energy consumption to a level comparable to that of biological synapses. In this work, hexagonal boron nitride (h-BN)-based metal-insulator-semiconductor (MIS) memristors operating is presented at the attojoule-level tailored for high-performance artificial neural networks. The memristors benefit from a wafer-scale uniform h-BN resistive switching medium grown directly on a highly doped Si wafer using metal–organic chemical vapor deposition (MOCVD), resulting in outstanding reliability and low variability. Notably, the h-BN-based memristors exhibit exceptionally low energy consumption of attojoule levels, coupled with fast switching speed. The switching mechanisms are systematically substantiated by electrical and nano-structural analysis, confirming that the h-BN layer facilitates the resistive switching with extremely low high resistance states (HRS) and the native SiO x on Si contributes to suppressing excessive current, enabling attojoule-level energy consumption. Furthermore, the formation of atomic-scale conductive filaments leads to remarkably fast response times within the nanosecond range, and allows for the attainment of multi-resistance states, making these memristors well-suited for next-generation neuromorphic applications. The h-BN-based MIS memristors hold the potential to revolutionize energy consumption limitations in neuromorphic devices, bridging the gap between artificial and biological synapses.

2. Adv. Opt. Mater.

   High-performance ceramic catalyst filters with textured waveguides for efficient removal of volatile organic compounds

   Jawon Kim^‡, Jeonghyeon Park^‡, Min Seok Koo^‡, Won Seok Cho, Seokho Moon, Inyong Hwang, Jaerim Kim, Jae Yong Park, Dong Jin Ham, Hyun Chul Lee^*, and Jong Kyu Kim^*

   Advanced Optical Materials 12, 2400746 (2024)

   Abs

   The cordierite-based ceramic catalyst filter (CCF) has attracted considerable attention as a promising future air purification system due to its ability to filtrate particulate matter (PM), as well as decompose volatile organic compounds (VOCs) through ultraviolet (UV)-activated photocatalytic reactions. Its performance, however, is strictly limited because majority of UV photons are absorbed near the entrance of the high-aspect-ratio air-flow channels, thus, only a limited portion of photocatalysts is activated during the flow of polluted air. In this study, a high-performance CCF is presented featuring textured waveguides (TWs) aligned with an array of UV light-emitting diodes (LEDs) emitting at a peak wavelength of 365 nm, which are inserted into an array of high-aspect-ratio channels. TWs ensure the delivery of UV photons deep inside channels via total internal reflection and scattering, enabling the activation of majority of photocatalysts, resulting in remarkable improvement in VOCs removal efficiency. The proposed CCF system exhibits much higher formaldehyde (HCHO) removal efficiency by 70% compared to conventional CCF systems even subjected to much lower UV light power densities. It is strongly believed that it is possible to further improve the removal efficiency, while maintaining effective PM filtering and ultralow electrical power consumption, by optimization of the geometry of the CCF system with TWs.

2023

1. Adv. Mater.

   Hexagonal boron nitride for next-generation photonics and electronics

   Seokho Moon^‡, Jiye Kim^‡, Jeonghyeon Park, Semi Im, Jawon Kim, Inyong Hwang, and Jong Kyu Kim^*

   Advanced Materials 35, 2204161 (2023)

   Abs

   Hexagonal boron nitride (h-BN), an insulating 2D layered material, has recently attracted tremendous interest motivated by the extraordinary properties it shows across the fields of optoelectronics, quantum optics, and electronics, being exotic material platforms for various applications. At an early stage of h-BN research, it is explored as an ideal substrate and insulating layers for other 2D materials due to its atomically flat surface that is free of dangling bonds and charged impurities, and its high thermal conductivity. Recent discoveries of structural and optical properties of h-BN have expanded potential applications into emerging electronics and photonics fields. h-BN shows a very efficient deep-ultraviolet band-edge emission despite its indirect-bandgap nature, as well as stable room-temperature single-photon emission over a wide wavelength range, showing a great potential for next-generation photonics. In addition, h-BN is extensively being adopted as active media for low-energy electronics, including nonvolatile resistive switching memory, radio-frequency devices, and low-dielectric-constant materials for next-generation electronics.

2. Chem. Mater.

   Conformal growth of hexagonal boron nitride on high-aspect-ratio silicon-based nanotrenches

   Jiye Kim, Kyung-Yeon Doh, Seokho Moon, Chang-Won Choi, Hokyeong Jeong, Jaewon Kim, Wonseok Yoo, Kyungwook Park, Kyeongock Chong, Chunhyng Chung, Hanmei Choi, Si-Young Choi^*, Donghwa Lee^*, and Jong Kyu Kim^*

   Chemistry of Materials 35, 2429–2438 (2023)

   Abs

   We successfully accomplished the conformal growth of sp 2 -hybridized few-layer h-BN over an array of Si-based nanotrenches with a 45 nm pitch and an aspect ratio of ∼7:1 by using the pulsed-mode metal–organic chemical vapor deposition (MOCVD) method. Surface-sensitive X-ray absorption fine structure spectroscopy and density functional theory calculations revealed that the B–O bonds formed on the noncatalytic SiO 2 surface act as nucleation sites for the subsequential formation of mixed sp 2 - and sp 3 -hybridized BON 2 and BN 3 at the very initial stage of the pulsed-mode injection of MOCVD precursors, enabling the conformal growth of few-layer sp 2 -hybridized h-BN with an excellent step coverage. We believe that these results can provide a broad avenue for the implementation of fascinating two-dimensional layered materials for current state-of-the-art three-dimensional Si-based nanoscale architectures, overcoming the downscaling limits.

2021

1. ACS Appl. Mater. Interfaces

   Van der Waals heterostructure of hexagonal boron nitride with an AlGaN/GaN epitaxial wafer for high-performance radio frequency applications

   Seokho Moon, Sung-Jae Chang, Youngjae Kim, Odongo Francis Ngome Okello, Jiye Kim, Jaewon Kim, Hyun-Wook Jung, Ho-Kyun Ahn, Dong-Seok Kim, Si-Young Choi, JaeDong Lee, Jong-Won Lim, and Jong Kyu Kim^*

   ACS Applied Materials & Interfaces 13, 59440–59449 (2021)

   Abs

   While two-dimensional (2D) hexagonal boron nitride (h-BN) is emerging as an atomically thin and dangling bond-free insulating layer for next-generation electronics and optoelectronics, its practical implementation into miniaturized integrated circuits has been significantly limited due to difficulties in large-scale growth directly on epitaxial semiconductor wafers. Herein, the realization of a wafer-scale h-BN van der Waals heterostructure with a 2 in. AlGaN/GaN high-electron mobility transistor (HEMT) wafer using metal–organic chemical vapor deposition is presented. The combination of state-of-the-art microscopic and spectroscopic analyses and theoretical calculations reveals that the heterointerface between ∼2.5 nm-thick h-BN and AlGaN layers is atomically sharp and exhibits a very weak van der Waals interaction without formation of a ternary or quaternary alloy that can induce undesired degradation of device performance. The fabricated AlGaN/GaN HEMT with h-BN shows very promising performance including a cutoff frequency (fT) and maximum oscillation frequency (fMAX) as high as 28 and 88 GHz, respectively, enabled by an effective passivation of surface defects on the HEMT wafer to deliver accurate information with minimized power loss. These findings pave the way for practical implementation of 2D materials integrated with conventional microelectronic devices and the realization of future all-2D electronics.

2. Mater. Lett.

   Structural evolution of hexagonal boron nitride powder by bead-milling

   Jaewon Kim^‡, Youngkwang Kim^‡, Odongo Francis Ngome Okello, Seokho Moon, Jiye Kim, Si-Young Choi, Junwoo Son^*, and Jong Kyu Kim^*

   Materials Letters 300, 130118 (2021)

   Abs

   The structural evolution of h-BN powder by bead-milling is investigated. A unique initial stage in h-BN milling is discovered in which the x-ray diffraction (XRD) out-of-plane (0 0 2) and (0 0 4) peak intensities increase distinctly up to 3 and 4.8 times respectively, corresponding to an effective c-axis ordering of the h-BN particles. The structural evolution of h-BN due to milling is correlated to the change in the dominant milling mechanism from out-of-plane cleaving to in-plane cutting. An abnormal contraction of out-of-plane (0 0 2) interplanar spacing up to 0.044 Å due to bead-milling is reported, which could be attributed to the introduction of oxygen functional groups (B-O and N-O) on the h-BN powder.

2020

1. ACS Appl. Mater. Interfaces

   Resistive switching in few-layer hexagonal boron nitride mediated by defects and interfacial charge transfer

   Hokyeong Jeong, Jiye Kim, Dong Yeong Kim, Jaewon Kim, Seokho Moon, Odongo Francis Ngome Okello, Sangmin Lee, Hyunsang Hwang, Si-Young Choi, and Jong Kyu Kim^*

   ACS Applied Materials & Interfaces 12, 46288–46295 (2020)

   Abs

   We present resistive switching (RS) behavior of few-layer hexagonal boron nitride (h-BN) mediated by defects and interfacial charge transfer. Few-layer h-BN is grown by metal–organic chemical vapor deposition and used as active RS medium in Ti/h-BN/Au structure, exhibiting clear bipolar RS behavior and fast switching characteristics about ∼25 ns without an initial electroforming process. Systematic investigation on microstructural and chemical characteristics of the h-BN reveals that there are structural defects such as homoelemental B–B bonds at grain boundaries and nitrogen vacancies, which can provide preferential pathways for the penetration of Tix+ ions through the h-BN film. In addition, the interfacial charge transfer from Ti to the h-BN is observed by in situ X-ray photoelectron spectroscopy. We suggest that the attractive Coulomb interaction between positively charged Tix+ ions and the negatively charged h-BN surface as a result of the interfacial charge transfer facilitates the migration of Tix+ ions at the Ti/h-BN interface, leading to the facile formation of conductive filaments. We believe that these findings can improve our understanding of the fundamental mechanisms involved in RS behavior of h-BN and contribute a significant step for the future development of h-BN-based nonvolatile memory applications.

2019

1. Sci. Rep.

   Wafer-scale and selective-area growth of high-quality hexagonal boron nitride on Ni(111) by metal-organic chemical vapor deposition

   Hokyeong Jeong, Dong Yeong Kim, Jaewon Kim, Seokho Moon, Nam Han, Seung Hee Lee, Odongo Francis Ngome Okello, Kyung Song, Si-Young Choi, and Jong Kyu Kim^*

   Scientific Reports 9, 5736 (2019)

   Abs

   We demonstrate wafer-scale growth of high-quality hexagonal boron nitride (h-BN) film on Ni(111) template using metal-organic chemical vapor deposition (MOCVD). Compared with inert sapphire substrate, the catalytic Ni(111) template facilitates a fast growth of high-quality h-BN film at the relatively low temperature of 1000 °C. Wafer-scale growth of a high-quality h-BN film with Raman E 2g peak full width at half maximum (FWHM) of 18-24 cm −1 is achieved, which is to the extent of our knowledge the best reported for MOCVD. Systematic investigation of the microstructural and chemical characteristics of the MOCVD-grown h-BN films reveals a substantial difference in catalytic capability between the Ni(111) and sapphire surfaces that enables the selective-area growth of h-BN at pre-defined locations over a whole 2-inch wafer. These achievement and findings have advanced our understanding of the growth mechanism of h-BN by MOCVD and will contribute an important step toward scalable and controllable production of high-quality h-BN films for practical integrated two-dimensional materials-based systems and devices.

2. Sci. Rep.

   Improvements in structural and optical properties of wafer-scale hexagonal boron nitride film by post-growth annealing

   Seung Hee Lee, Hokyeong Jeong, Odongo Francis Ngome Okello, Shiyu Xiao, Seokho Moon, Dong Yeong Kim, Gi-Yeop Kim, Jen-Iu Lo, Yu-Chain Peng, Bing-Ming Cheng, Hideto Miyake, Si-Young Choi, and Jong Kyu Kim^*

   Scientific Reports 9, 10590 (2019)

   Abs

   Remarkable improvements in both structural and optical properties of wafer-scale hexagonal boron nitride (h-BN) films grown by metal-organic chemical vapor deposition (MOCVD) enabled by high-temperature post-growth annealing is presented. The enhanced crystallinity and homogeneity of the MOCVD-grown h-BN films grown at 1050 °C is attributed to the solid-state atomic rearrangement during the thermal annealing at 1600 °C. In addition, the appearance of the photoluminescence by excitonic transitions as well as enlarged optical band gap were observed for the post-annealed h-BN films as direct consequences of the microstructural improvement. The post-growth annealing is a very promising strategy to overcome limited crystallinity of h-BN films grown by typical MOCVD systems while maintaining their advantage of multiple wafer scalability for practical applications towards two-dimensional electronics and optoelectronics.