Electronic band gap of van der Waals α-As₂Te₃ crystals

van der Waals materials offer a large variety of electronic properties depending on chemical composition, number of layers, and stacking order. Among them, As₂Te₃ has attracted attention due to the promise of outstanding electronic properties and high photo-response. Precise experimental determinations of the electronic properties of As₂Te₃ are yet sorely needed for better understanding of potential properties and device applications. Here, we study the structural and electronic properties of α-As₂Te₃. Scanning transmission electron microscopy coupled to energy x-ray dispersion and micro-Raman spectroscopy all confirm that our specimens correspond to α-As₂Te₃. Scanning tunneling spectroscopy (STS) at 4.2 K demonstrates that α-As₂Te₃ exhibits an electronic bandgap of about 0.4 eV. The valence-band maxima are located at −0.03 eV below the Fermi level, thus confirming the residual p-type character of our samples. The material can be exfoliated, revealing the (100) anisotropic surface. Transport measurements on a thick exfoliated sample (bulk-like) confirm the STS results. These findings allow for a deeper understanding of the As₂Te₃ electronic properties, underlying the potential of V-VI semiconductors for electronic and photonic technologies.