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Half-Heusler intermetallic compounds have been an important subject of interest in the field of semiconductors for years, but have been studied more for their bulk structure and rarely for their two-dimensional structure. Here, a novel two-dimensional semiconductor material with the chemical formula TiPtGe and an indirect bandgap of 1.27 eV has been developed on the basis of first-principles calculations. Significantly, it could be transformed from an indirect to a direct bandgap semiconductor under small biaxial in-plane strain. Given the similar lattice parameters and symmetry with the single-element two-dimensional material antimonene, we have attempted to form a vertical heterostructure of the two. The calculated results show that the heterostructure can be transformed from an indirect to a direct bandgap by increasing the number of TiPtGe layers. Further calculated results of the optical properties show that increasing the number of TiPtGe layers in the heterostructure could significantly improve the absorption efficiency in the visible region. This provides a new possibility for the application of antimonene in optoelectronic devices.

Antimonene is a novel two-dimensional topological semiconductor material with a strain-driven tunable electronic structure for future electronic devices, but the growth of clean antimonene is not fully understood. In this work, the growth process of antimonene on the silver substrate has been studied in detail by using the density functional theory and particle swarm optimization algorithms. The results show that, in addition to the experimental reported flat honeycomb and β-phase antimonene, α-phase antimonene was observed to be able to grow on the substrates, and the phases of antimonene were deeply dependent on the reconstructed supercells and surface alloys. It has been demonstrated that the surface alloys on the substrate play an active role in the growth of antimonene.

Metal chalcogenides are a promising material for novel physical research and nanoelectronic device applications. Here, we systematically investigate the crystal structure and electronic properties of AlSe alloys on Al(111) using scanning tunneling microscopy, angle-resolved photoelectron spectrometry, and first-principle calculations. We reveal that the AlSe surface alloy possesses a closed-packed atomic structure. The AlSe surface alloy comprises two atomic sublayers (Se sublayer and Al sublayer) with a height difference of 1.16 Å. Our results indicate that the AlSe alloy hosts two hole-like bands, which are mainly derived from the in-plane orbital of AlSe (p x and p y ). These two bands located at about −2.22 ±0.01 eV around the Gamma point, far below the Fermi level, distinguished from other metal chalcogenides and binary alloys. AlSe alloys have the advantages of large-scale atomic flat terraces and a wide band gap, appropriate to serve as an interface layer for two-dimensional materials. Meanwhile, our results provide implications for related Al-chalcogen interfaces.