Band engineering in a van der Waals heterostructure using a 2D polar material and a capping layer

Enhanced Versatility of Table-Top X-Rays from Van der Waals Structures

Van der Waals (vdW) materials have attracted much interest for their myriad unique electronic, mechanical, and thermal properties. In particular, they are promising candidates for monochromatic, table-top X-ray sources. This work reveals that the versatility of the table-top vdW X-ray source goes beyond what has been demonstrated so far. By introducing a tilt angle between the vdW structure and the incident electron beam, it is theoretically and experimentally shown that the accessible photon energy range is more than doubled. This allows for greater versatility in real-time tuning of the vdW X-ray source. Furthermore, this work shows that the accessible photon energy range is maximized by simultaneously controlling both the electron energy and the vdW structure tilt. These results will pave the way for highly tunable, compact X-ray sources, with potential applications including hyperspectral X-ray fluoroscopy and X-ray quantum optics.

Ideal inert substrates for planar antimonene: h-BN and hydrogenated SiC(0001)

Planar antimonene, as one of the most promising two-dimensional materials, was recently obtained on a Ag(111) substrate [Y. Shao, Z. L. Liu, et al., Nano Lett., 2018, 18, 2133]. However, its particular electronic properties are severely degraded due to the substrate, making its further study and practical applications challenging. Here, using first-principles calculations, we propose that h-BN and hydrogenated SiC(0001) are extraordinary substrates of planar antimonene. Their interactions with planar antimonene exhibit low binding energies and large interlayer distances, and are typical van der Waals interactions. Most importantly, the bands of planar antimonene near the Fermi level are perfectly preserved, with the bands of h-BN and hydrogenated SiC(0001) lying away from the Fermi level. Moreover, such features are inert to the stacking patterns for both systems, making them suitable for practical applications. Our results will greatly broaden the scientific and technological impact of planar antimonene.

Electronic and optical properties of boron phosphide/blue phosphorus heterostructures

The dynamically stable boron-phosphide/blue-phosphorus heterostructures are a good UV absorber while being transparent in the visible region.