The combination of semiconductor and ferroics (ferromagnetism, ferroelectricity, and ferroelasticity) can endow it with the function of nonvolatile memory. The magnetic and semiconducting properties of traditional semiconductors (such as Si, GaAs) can be combined by doping magnetic ions, while their Curie temperature can scarcely reach room temperature, and similar doping is even more difficult  for two-dimensional materials; ferroelectricity and ferroelasticity have more chance to survive at room temperature, but cannot be obtained through similar doping.

On October 19th, nanoscience authoritative journal Nano Letters published online an research paper of Wu Menghao, a new professor of the School of Physics of HUST, as the first author and co-corresponding author, entitled “Ferroelectricity in Covalently functionalized Two-dimensional Materials: Integration of High-mobility Semiconductors and Nonvolatile Memory” - Other co-authors include professor Dong Shuai of the Southeast University, professor Yao Kailun of the School of Physics of HUST, professor Liu Junming of Nanjing University and professor Zeng Xiaocheng of the University of Nebraska, in which professor Liu Junming and professor Zeng Xiaocheng are the co-corresponding authors.

Through first-principles calculations it is shown that the modification of some polar chemical groups on the surface can endow a series of non-ferroelectric systems with ferroelectricity with high Curie temperature. The non-ferroelectric systems include a series of well-known two-dimensional material like graphene, germanene and MoS₂, or the (111) surface of silicon or III-V semiconductors, or silica surfaces used as the substrates of two-dimensional materials, and many of those systems have been synthesized in previous experiments. They can be directly integrated in the circuit based on the traditional semiconductors or two-dimensional materials, and are expected to combine the high-mobility of narrow band gap semiconductors with ferroics at room temperature, thus, a series of multifunctional heterojunction devices can be designed: two-dimensional ferroelectric field effect transistors with high on/off ratio, topological transistors with Dirac fermions tunable between electrons and holes, two dimensional ferroelectric or even multi-ferroic tunneling junctions, and so on, making both non-destructive reading and fast writing of  information possible. Hence, they possess important application value in the future multi-functional devices.

Professor Wu Menghao joined in the Institute of Condensed Matter Physics at the end of 2014. Before then, he has studied in the University of Nebraska, the of Virginia Commonwealth University and the Massachusetts Institute of Technology in the United States; he has been dedicated to the theoretical research on physical and chemical properties of the confined Nanosystem, and made a series of achievements in research attracting considerable domestic and international attention.

This work was supported by the Talent Introduction Fund of Huazhong University of Science and Technology and the National Natural Science Foundation of china.