Highly efficient, deep-ultraviolet luminescence in hBN moiré quantum wells.
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| Title: | Highly efficient, deep-ultraviolet luminescence in hBN moiré quantum wells. |
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| Authors: | Hong, Chengyun (AUTHOR), Zhao, Fangzhou (AUTHOR), Song, Su-Beom (AUTHOR), Yoon, Sangho (AUTHOR), Jeon, Seong-Joon (AUTHOR), Khan, M. Ajmal (AUTHOR), Tao, Ye (AUTHOR), Yang, Dong-Hwan (AUTHOR), Lee, Wanhee (AUTHOR), Kim, Junho (AUTHOR), Yang, Sera (AUTHOR), Cho, Hyungseob (AUTHOR), Lee, Sumin (AUTHOR), Min, Seok Young (AUTHOR), Watanabe, Kenji (AUTHOR), Taniguchi, Takashi (AUTHOR), Yoo, Seunghyup (AUTHOR), Cho, Changsoon (AUTHOR), Choi, Si-Young (AUTHOR), Hirayama, Hideki (AUTHOR) |
| Source: | Science. 3/19/2026, Vol. 391 Issue 6791, p1-9. 9p. |
| Subjects: | Quantum wells, Luminescence, Electroluminescence, Photoluminescence |
| Abstract: | 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. Editor's summary: Moiré quantum wells formed in twisted homojunctions of bulk hexagonal boron nitride emit bright luminescence in the deep ultraviolet. Hong et al. found that restacking the bulk layers with a marginal twist angle created a stacking-order superlattice at the twisted interface (see the Perspective by Gil and Cassabois). Phonon-assisted luminescence was excited in the far–ultraviolet C range upon photoexcitation or electrical carrier injection. The emission was about 20 times stronger than that of conventional aluminum gallium nitride multiple quantum wells. —Phil Szuromi INTRODUCTION: Twisted stacking of two-dimensional (2D) van der Waals (vdW) semiconductors creates moiré superlattices that enable unprecedented control over quantum states and light-matter interactions. To date, such phenomena have been primarily explored in atomically thin materials, where interlayer coupling profoundly modifies the electronic structures and excitonic properties of the constituent layers. RATIONALE: Extending moiré engineering into three-dimensional (3D) vdW layered materials provides new opportunities to exploit their inherently strong light-matter interactions and anisotropic electronic structures. Electrons in these 3D crystals exhibit enhanced in-plane mobility and polarization-dependent optical responses, enabling highly efficient optical processes. Introducing controlled twist angles between 3D vdW layers can thus form a new class of moiré architectures that support carrier localization, tunable excitonic behavior, and vdW integration with photonic and optoelectronic devices, all capabilities that surpass those of twisted 2D materials. Recent studies have shown that twisting bulk single crystals can create mechanically robust and reconfigurable moiré interfaces, paving the way for nonlinear and quantum optical functionalities governed by twist angle. Nevertheless, the interfacial electronic states and optical characteristics of such twisted bulk vdW materials remain largely unexplored. RESULTS: Here, we demonstrate the formation of quantum wells (QWs) at homojunction interfaces of twisted bulk vdW crystals using hexagonal boron nitride (hBN) as a model system. The resulting moiré superlattices confine charge carriers within atomically thin, periodic potential wells embedded in a 3D semiconductor matrix. Deep-ultraviolet (DUV) femtosecond laser spectroscopy reveals that the periodic modulation of stacking order produces robust moiré potentials, reducing the local optical bandgap by up to about 300 milli–electron volts. Remarkably, twisted hBN homojunctions exhibit intense phonon-assisted luminescence in the far–ultraviolet-C (far-UV-C) range (5.2 to 5.8 electron volts and 215 to 240 nanometers) under both optical excitation and electrical carrier injection. By tuning the twist angle, we achieved a substantial enhancement in luminescence intensity more than an order of magnitude stronger than that of state-of-the-art AlGaN multi-QWs. These observations are well supported by ab initio GW plus Bethe-Salpeter equation (GW-BSE) calculations (where GW is the product of Green's function G and the screened Coulomb interaction W), which confirm the twist-angle–dependent modulation of band structure and exciton localization. CONCLUSION: Our results establish twisted bulk hBN homojunctions as a new class of QWs that exhibit exceptionally efficient DUV emission, surpassing even conventional wide-bandgap semiconductors such as aluminum gallium nitride (AlGaN) QWs with near-unity internal quantum yield. Combining DUV femtosecond spectroscopy and first-principles theory, we showed that interfacial moiré superlattices localize excitons and facilitate efficient phonon-assisted radiative recombination. Furthermore, our proof-of-concept electrically driven devices demonstrate strong electroluminescence from twisted hBN regions, underscoring the promise of moiré engineering in bulk vdW materials for future UV-C optoelectronics. Beyond hBN, this mechanism of twist-induced carrier confinement and enhanced phonon-mediated recombination offers a general framework for realizing tunable, robust, and efficient light-matter interactions across a broad spectral range in 3D vdW semiconductors. Highly efficient DUV luminescence in hBN moire QWs.: Schematic illustration of moiré QW formation at the twist interface of hBN bulks. hBN moiré QWs strongly localize excitons that emit remarkably strong luminescence at DUV frequencies. [ABSTRACT FROM AUTHOR] |
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| Database: | Psychology and Behavioral Sciences Collection |
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| Abstract: | 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. Editor's summary: Moiré quantum wells formed in twisted homojunctions of bulk hexagonal boron nitride emit bright luminescence in the deep ultraviolet. Hong et al. found that restacking the bulk layers with a marginal twist angle created a stacking-order superlattice at the twisted interface (see the Perspective by Gil and Cassabois). Phonon-assisted luminescence was excited in the far–ultraviolet C range upon photoexcitation or electrical carrier injection. The emission was about 20 times stronger than that of conventional aluminum gallium nitride multiple quantum wells. —Phil Szuromi INTRODUCTION: Twisted stacking of two-dimensional (2D) van der Waals (vdW) semiconductors creates moiré superlattices that enable unprecedented control over quantum states and light-matter interactions. To date, such phenomena have been primarily explored in atomically thin materials, where interlayer coupling profoundly modifies the electronic structures and excitonic properties of the constituent layers. RATIONALE: Extending moiré engineering into three-dimensional (3D) vdW layered materials provides new opportunities to exploit their inherently strong light-matter interactions and anisotropic electronic structures. Electrons in these 3D crystals exhibit enhanced in-plane mobility and polarization-dependent optical responses, enabling highly efficient optical processes. Introducing controlled twist angles between 3D vdW layers can thus form a new class of moiré architectures that support carrier localization, tunable excitonic behavior, and vdW integration with photonic and optoelectronic devices, all capabilities that surpass those of twisted 2D materials. Recent studies have shown that twisting bulk single crystals can create mechanically robust and reconfigurable moiré interfaces, paving the way for nonlinear and quantum optical functionalities governed by twist angle. Nevertheless, the interfacial electronic states and optical characteristics of such twisted bulk vdW materials remain largely unexplored. RESULTS: Here, we demonstrate the formation of quantum wells (QWs) at homojunction interfaces of twisted bulk vdW crystals using hexagonal boron nitride (hBN) as a model system. The resulting moiré superlattices confine charge carriers within atomically thin, periodic potential wells embedded in a 3D semiconductor matrix. Deep-ultraviolet (DUV) femtosecond laser spectroscopy reveals that the periodic modulation of stacking order produces robust moiré potentials, reducing the local optical bandgap by up to about 300 milli–electron volts. Remarkably, twisted hBN homojunctions exhibit intense phonon-assisted luminescence in the far–ultraviolet-C (far-UV-C) range (5.2 to 5.8 electron volts and 215 to 240 nanometers) under both optical excitation and electrical carrier injection. By tuning the twist angle, we achieved a substantial enhancement in luminescence intensity more than an order of magnitude stronger than that of state-of-the-art AlGaN multi-QWs. These observations are well supported by ab initio GW plus Bethe-Salpeter equation (GW-BSE) calculations (where GW is the product of Green's function G and the screened Coulomb interaction W), which confirm the twist-angle–dependent modulation of band structure and exciton localization. CONCLUSION: Our results establish twisted bulk hBN homojunctions as a new class of QWs that exhibit exceptionally efficient DUV emission, surpassing even conventional wide-bandgap semiconductors such as aluminum gallium nitride (AlGaN) QWs with near-unity internal quantum yield. Combining DUV femtosecond spectroscopy and first-principles theory, we showed that interfacial moiré superlattices localize excitons and facilitate efficient phonon-assisted radiative recombination. Furthermore, our proof-of-concept electrically driven devices demonstrate strong electroluminescence from twisted hBN regions, underscoring the promise of moiré engineering in bulk vdW materials for future UV-C optoelectronics. Beyond hBN, this mechanism of twist-induced carrier confinement and enhanced phonon-mediated recombination offers a general framework for realizing tunable, robust, and efficient light-matter interactions across a broad spectral range in 3D vdW semiconductors. Highly efficient DUV luminescence in hBN moire QWs.: Schematic illustration of moiré QW formation at the twist interface of hBN bulks. hBN moiré QWs strongly localize excitons that emit remarkably strong luminescence at DUV frequencies. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00368075 |
| DOI: | 10.1126/science.aeb2095 |
