Emergent Electronic, Spin, and Transport Properties of Bilayer van der Waals Heterostructures from Antimonene, Tellurene, and PtTe2 Monolayers

The assembly of two-dimensional (2D) materials into van der Waals heterostructures (vdWHs) provides an effective platform for tailoring the physical properties of individual 2D materials. In this work, based on three centrosymmetric monolayers, namely, antimonene, tellurene, and PtTe2, we construct three stable bilayer vdWHs: antimonene (Sb)/tellurene (Te), antimonene (Sb)/PtTe2, and tellurene (Te)/PtTe2. Using first-principles calculations, we systematically investigate their electronic, spintronic, optical, piezoelectric, and transport properties. Our results show that heterostructure formation breaks spatial inversion symmetry and induces strong interlayer hybridization, which together with the strong spin–orbit coupling significantly reduce the bandgaps and trigger pronounced spin splitting in their band structures. Among the three systems, the Sb/PtTe2 bilayer exhibits a type-III broken-gap band alignment, with obvious tunneling effect, suggesting its potential for tunneling field-effect transistor applications. In contrast, the Sb/Te and Te/PtTe2 systems are small-bandgap type-I vdWHs, in which both the valence band maxima and conduction band minima are mainly contributed by tellurene. More importantly, the conduction band minima of the Sb/Te and Te/PtTe2 vdWHs and the valence band top of the Sb/PtTe2 vdWH exhibit extraordinary Rashba effects, with Rashba coefficients reaching 1.08, 2.89, and 2.85 eV Å, respectively. The Rashba effects can be further tuned by an external strain and electric field, and the coefficient of the Te/PtTe2 vdWH can be enhanced to 3.45 eV Å under 6% tensile strain. In addition, compared with their constituent monolayers, the three vdWHs exhibit greatly enhanced optical absorption in the visible-light region and notable in-plane and out-of-plane piezoelectric responses. Meanwhile, the carrier mobilities of the Sb/Te and Te/PtTe2 vdWHs are also significantly improved, up to 104 cm2 V–1 s–1. The designed vdWHs, with their diverse and highly tunable properties, hold great promise for applications in nanoelectronic, optoelectronic, piezoelectric, and spintronic devices.