Twisted stacking of two-dimensional van der Waals (vdW) semiconductors creates moiré superlattices, which provides unprecedented control over quantum states and their light-matter interactions. We demonstrate that a simple twist interface between two single-crystalline bulks of hexagonal boron nitride (hBN) creates moiré quantum wells (QWs) embedded in a three-dimensional vdW structure. hBN moiré QWs strongly confine charge carriers under both optical excitation and electrical injection. Despite their indirect bandgap, they emit intense deep-ultraviolet luminescence in the extreme wavelength bands from 215 to 240 nanometers, exceeding that of state-of-the-art conventional aluminum gallium nitride (AlGaN) multiple QWs by more than an order of magnitude. Furthermore, the twist angle control allows wide tunability of luminescence energy and efficiency in moiré QWs.

Antimony (Sb) is an intriguing material for advanced electronics, with thickness-dependent properties at the nanoscale offering new functionalities. However, conventional methods for depositing Sb thin films cannot produce continuous ultrathin films with conformality in complex nanoscale structures. This study introduces a novel sacrificial atomic layer deposition (s-ALD) approach that overcomes these limitations by using chemical substitution between the antimony precursor and the pre-deposited Sb₂Te₃. The structural similarity between Sb₂Te₃ and Sb enables local epitaxial growth of a uniform, (00l)-oriented Sb film with exceptional surface smoothness (root-mean-squared roughness << 1 nm) at a 4-nm thickness. Highly pure Sb films with excellent wafer-scale uniformity and conformality are achieved on high-aspect-ratio structures. The mechanism involves substitution reactions driven by the preferential Te-(CH₃)₃Si bonding, along with enhanced atomic diffusion through the aligned crystal structure. Phase change memory devices using 5-nm-thick s-ALD Sb films demonstrate ultrafast switching with femtosecond laser pulses (≈220 fs) with high device-to-device uniformity (coefficient of variation < 5 %) and ultralow drift coefficients (0.0013 for the on state and 0.0073 for the off state). This s-ALD technique offers a promising pathway for depositing ultrathin, uniform Sb films, enabling full utilization of Sb's unique nanoscale properties.

We developed a novel moisture-induced power generator by utilizing Berlin green as an active material to enhance its moisture-electric energy transformation performance.

Adv. Funct. Mater. 2018, 28, 1703074 The acknowledgements as initially published for this manuscript are missing a funding statement. The corrected acknowledgements should read as follows: This work was supported by a grant from the National R&D Program for Cancer Control, Ministry of Health and Welfare, Republic of Korea (1420390), the National Research Foundation of Korea (NRF) grant funded by the Korea government (2017R1A2B2010292 and 2017R1A3B1023418), the KU-KIST Graduate School of Converging Science and Technology Program, and the KIST Institutional Program. The authors apologize for any inconvenience or misunderstanding that this error may have caused.

Twisted stacking of two-dimensional van der Waals (vdW) semiconductors creates moiré superlattices, which provides unprecedented control over quantum states and their light-matter interactions. We demonstrate that a simple twist interface between two single-crystalline bulks of hexagonal boron nitride (hBN) creates moiré quantum wells (QWs) embedded in a three-dimensional vdW structure. hBN moiré QWs strongly confine charge carriers under both optical excitation and electrical injection. Despite their indirect bandgap, they emit intense deep-ultraviolet luminescence in the extreme wavelength bands from 215 to 240 nanometers, exceeding that of state-of-the-art conventional aluminum gallium nitride (AlGaN) multiple QWs by more than an order of magnitude. Furthermore, the twist angle control allows wide tunability of luminescence energy and efficiency in moiré QWs.

Antimony (Sb) is an intriguing material for advanced electronics, with thickness-dependent properties at the nanoscale offering new functionalities. However, conventional methods for depositing Sb thin films cannot produce continuous ultrathin films with conformality in complex nanoscale structures. This study introduces a novel sacrificial atomic layer deposition (s-ALD) approach that overcomes these limitations by using chemical substitution between the antimony precursor and the pre-deposited Sb₂Te₃. The structural similarity between Sb₂Te₃ and Sb enables local epitaxial growth of a uniform, (00l)-oriented Sb film with exceptional surface smoothness (root-mean-squared roughness << 1 nm) at a 4-nm thickness. Highly pure Sb films with excellent wafer-scale uniformity and conformality are achieved on high-aspect-ratio structures. The mechanism involves substitution reactions driven by the preferential Te-(CH₃)₃Si bonding, along with enhanced atomic diffusion through the aligned crystal structure. Phase change memory devices using 5-nm-thick s-ALD Sb films demonstrate ultrafast switching with femtosecond laser pulses (≈220 fs) with high device-to-device uniformity (coefficient of variation < 5 %) and ultralow drift coefficients (0.0013 for the on state and 0.0073 for the off state). This s-ALD technique offers a promising pathway for depositing ultrathin, uniform Sb films, enabling full utilization of Sb's unique nanoscale properties.

We developed a novel moisture-induced power generator by utilizing Berlin green as an active material to enhance its moisture-electric energy transformation performance.

Adv. Funct. Mater. 2018, 28, 1703074 The acknowledgements as initially published for this manuscript are missing a funding statement. The corrected acknowledgements should read as follows: This work was supported by a grant from the National R&D Program for Cancer Control, Ministry of Health and Welfare, Republic of Korea (1420390), the National Research Foundation of Korea (NRF) grant funded by the Korea government (2017R1A2B2010292 and 2017R1A3B1023418), the KU-KIST Graduate School of Converging Science and Technology Program, and the KIST Institutional Program. The authors apologize for any inconvenience or misunderstanding that this error may have caused.

Novel microcantilevers withnanochannels fabricated from anodicaluminum oxide (AAO) are described. Cantilevers based on AAO canprecisely control the dimensions ofthe nanochannels and provide surface areas several orders of magnitudelarger than conventional siliconcantilevers with flat surfaces.

Hyperbolic media enable unique optical phenomena including hyperlensing, negative refraction, enhanced photonic density of states (PDOS), and highly confined polaritons. While most hyperbolic media are artificially engineered metamaterials, certain natural materials with extreme anisotropy can exhibit hyperbolic dispersion. Here, based on experimental evidence and theoretical fitting estimates to the experimental data, we suggest the presence of natural hyperbolic dispersion in hexagonal boron nitride (hBN) in the deep-ultraviolet (DUV) regime, induced by strong, anisotropic exciton resonances. Using all-optical imaging spectroscopic ellipsometry (ISE), we characterize the complex dielectric function along in-plane and out-of-plane directions down to 190 nm (6.53 eV), revealing a potential type-II hyperbolic window in the DUV regime. We predict that hyperbolicity supports hyperbolic exciton polaritons (HEP) with high directionality and slow group velocity, as confirmed by numerical calculations. Our findings suggest hBN as a platform for nanophotonic applications in the technologically significant DUV spectral range.