High-Performance Violet Phosphorene-Based Device via Tellurium Doping-Induced Contact Resistance Reduction

Two-dimensional materials have attracted much attention in various research fields. The phosphorene structures with various allotropes, another type of elemental 2D materials after graphene, have been demonstrated to have unique optoelectronic and photoelectronic properties. However, an inert environment is required to measure phosphorene-based field effect transistors. The experimentally obtained charge mobility from devices is significantly lower than the intrinsic values due to high contact resistance between phosphorene and electrodes. Here, tellurium atoms have been introduced for the first time to significantly lower the contact resistance, enabling measurements under ambient conditions to obtain high charge mobility. The crystal structure of violet tellurium phosphorus was determined by single-crystal X-ray diffraction to keep the same crystal structure as violet phosphorus, where the P9 position is occupied by tellurium/phosphorus atoms as a mixed Te1/P9 site. The p-type violet phosphorene nanosheet (2.04 cm² V^-1 s^-1) was switched into a high-performance n-type violet tellurium phosphorene nanosheet (134.12 cm² V^-1 s^-1). The contact resistance between channel materials and electrodes was found to be significantly reduced from 550-860 MΩ for violet phosphorene nanosheets to 1.13-1.80 MΩ for violet tellurium phosphorene nanosheets due to tellurium substitution, resulting in robust performance of violet phosphorene under ambient conditions.