Definition of "monolayer"

Recently a stable monolayer of antimony in buckled honeycomb structure called antimonene was successfully grown on 3D topological insulator Bi 2 {\displaystyle _{2}} Te 3 {\displaystyle _{3}} and Sb 2 {\displaystyle _{2}} Te 3 {\displaystyle _{3}} , which displays semiconducting properties.

2016, Yuanfeng Xu, Bo Peng, Hao Zhang, Hezhu Shao, Rongjun Zhang, Hongliang Lu, David Wei Zhang, Heyuan Zhu, “First-principle calculations of phononic, electronic and optical properties of monolayer arsenene and antimonene allotropes”, in arXiv‎