北京高压科学研究中心
Center for High Pressure Science &Technology Advanced Research

Novel 2D silicon with flat surface - Dr. Duckyoung Kim

FEBURAR 28, 2018


New work from a team of scientists including Dr. Duckyoung Kim from HPSTAR have predicted a serials of novel layered silicon crystals with stable flat surface structure and versatile electronic structures. They proposed that their study will help the development of silicon-based two dimensional electronic technology. The study is published in recent 2D Materials. 

Silicon, is one of the most common elements on Earth. Bulk silicon is extremely stable and has been used in integrated circuits and transistors that run most of our computers.

Silicene, is a two-dimensional form of silicon, an analog to graphene, which has been predicted to have promising properties and potential applications. While contrary to graphene, silicene cannot form a stable layered structure by itself since surface of the silicene is chemically reactive. Thus great challenges remained to fabricated silicene.

Instead of silicene, the team of scientists turned attention to a new direction— to find a novel two dimensional silicone structures. 

By using a newly developed ab initio computational method, the team of scientists including Drs. Kisung Chae of Korea Institute for Advanced Study, Duckyoung Kim of HPSTAR and Dr. Youn-Woo Son of Korea Institute for Advanced Study, have predicted a series of novel two dimensional silicon structures with versatile electronic properties. The predicted crystal is composed of two parts: the atomically flat surface layers and the inner layer connecting them through sp3-like covalent bonds. The surface layer features perfectly planar stable hexagonal framework unlike silicone with buckled surfaces. They classified the two dimensional Si structures into three groups and each of the groups possesses distinct electronic properties originated from structural variations such as semiconductor as well as semimetals.

“As we intentionally put together two symmetrically distinct parts (surface and inner layers) so that unsaturated bonds on both layers are fully compensated by each other, all the silicon atoms in the crystal have saturated bonds without any dangling bonds”, explained in the paper.

They believe that the new 2D Si crystals satisfy highly desirable characteristics of next generation electronic technology platforms only with a single atomic element and their oxides, very similar with the current 3D Si electronic devices.

“The method is especially suited for predicting 2D phases of covalent materials by designing the 2D crystals free of CN defects. This can be achieved by building surface and inner parts with different symmetries from each other, and by joining the two parts in such a way that under-coordinated atoms at the interface are compensated by one another. By doing so, the crystal becomes stabilized by eliminating dangling bonds”, stated in the paper.