Electrical Transport of One-Dimensional Atomic Tellurium Nanowires Scaling Down to Two Nanometer Limit

Due to the capability of forming air-stable thin films with high carrier mobility up to 800 cm² V^-1 s^-1 at room temperature, tellurium (Te) as a chalcogen has shown its excellent potential in the field of semiconductor devices. As a narrow-bandgap p-type semiconductor, bulk Te has a direct bandgap of ~0.35 eV. Besides, Te has a unique crystal structure composed by helical chains. Each Te atom is covalently bonded with the other two adjacent Te atoms to form a spiral chain, and bulk crystal is consist of numerous chains stacked by van der Waals interaction. Here, we systematically studied the electronic transport properties of 1D Te devices scaling down to 2 nm limit in diameter. Since the native oxidation and degradation of 1D Te nanowires (NWs), the limit of bare Te NWs to exhibit stable electronic signal is around 6-7 nm. In order to further explore the performance of thinner Te NWs, we grew Te atomic chains into boron nitride nanotubes (BNNTs) and realized its field effect successfully down to 2 nm limit. Due to the encapsulation of BNNTs, the on-state current can even be dramatically increased. Moreover, the phonon responses of 1D Te NWs have also been investigated from bulk form down to a single atomic chain limit by encapsulation of carbon nanotubes (CNTs).