Electrical and Optical Characterization of Ultrathin Tellurium Nanostructures Synthesized by Vapor Phase Deposition*

Tellurium (Te) is a semiconductor with a slightly indirect bulk bandgap of 0.35 eV. The trigonal crystal structure of Te consists of 1D helical chains of Te atoms stacked together by van der Waals type bonds arranged on 2D hexagonal lattice. Each Te atom is covalently bonded with its two nearest neighbors on the same chain. This unique crystal structure allows a stable 1T-MoS₂-like α-Te, a metastable tetragonal β-Te, and a 2H-MoS₂–like γ-Te structures. The α- and γ-Te phases are expected to have nearly direct band gaps and high carrier motilities suggesting potential applications in electronic and optoelectronic devices. Here we present the vapor phase synthesis and characterization of novel ultrathin Te nanostructures having thickness down to 3.5 nm. Room temperature (RT) electrical measurements exhibit p-type semiconductor with field effect hole mobility of ~350 cm²/V.s. The low-temperature transport properties, RT micro-photoluminescence, and structural properties of the Te nanostructures will also be presented.