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Two-dimensional (2D) transition metal silicon nitrides (MSi2N4: M denotes Mo or W) are promising channel materials for nanoelectronics owing to their attractive structural and electronic properties. The integration of high-κ dielectrics into 2D semiconductors MSi2N4 is one of the vital steps for achieving high-performance electronic devices, which however remains challenging. In this study, we propose silicon nitride (Si3N4) as the native high-κ dielectric for 2D MSi2N4 and reveal their interfacial properties. Using first-principles calculations, we show that a high-performance interface can be formed, as supported by weak interface interaction, insignificant charge density redistribution, and nearly intact electronic properties of monolayer MSi2N4 with the integration of Si3N4. We further demonstrate that interfacial hydrogenation can effectively passivate the dangling bonds at the Si3N4 surface, leading to improved interface performance. Importantly, this interfacial hydrogenation does not bring a detrimental effect to both the high-κ dielectric and the 2D semiconductors, as it is thermodynamically and kinetically stable at the Si3N4 surface. These results provide a deep understanding for the integration of high-κ dielectrics on 2D semiconductors MSi2N4, design a viable interfacial engineering strategy to improve the interface performance, and therefore could be useful for the development of 2D MSi2N4 based high-performance electronics. [ABSTRACT FROM AUTHOR]

Despite the considerable potential and significant promise of aluminum scandium nitride (AlScN) ferroelectric materials for neuromorphic computing applications, challenges related to device engineering, along with the considerable structural disorder in thin films grown on various substrates using different vapor synthesis methods, make it difficult to systematically study the structure–property relationship. In this work, we approach such issues from the crystal growth side by successfully growing high-quality single crystal AlScN nanowires through ultra-high vacuum reactive sputtering under high substrate bias and low atomic flux conditions, which leads to simultaneous growth and etching. Characterization of nanowire arrays using X-ray diffraction and transmission electron microscopy shows that the wires are epitaxial single crystals with significantly reduced mosaic spread and predominantly single ferroelectric domains. Moreover, ferroelectric and piezoelectric properties were evaluated using Piezoresponse Force Microscopy. The single crystal AlScN nanowires show an out-of-plane piezoelectric constant d33 that is greater than 20 pm V−1, which is higher than that of pure AlN by a factor of ∼4. [ABSTRACT FROM AUTHOR]