Xuan Gao (CWRU Physics)

Date: Thu. November 9th, 2017, 4:00 pm-5:00 pm
Location: Rockefeller 301

2D Materials: from Semiconductors to Topological Insulators

Abstract: Since the first isolation of one-atom thick graphene, research on two-dimensional (2D) materials with layered crystal structure has exploded over the past decade. One focal point in the recent studies of 2D materials beyond graphene is the development of metal chalcogenides (e.g. MoS₂) as 2D semiconductors. In this talk, I will first highlight our exploration of non-transition metal chalcogenides InSe and SnS for future 2D semiconductor applications. While multilayer InSe is demonstrated to be a promising new 2D semiconductor for high performance n-type transistor devices, SnS’s intrinsic p-type nature leads to both opportunities and challenges in p-type semiconductor device applications. I will then discuss layered V-VI chalcogenides (Bi₂Se₃, Bi₂Te₃ etc) in which the strong spin-orbit interaction turns the material from a normal insulator (or semiconductor) into the so-called ‘topological insulator’, a novel quantum state of matter where metallic gapless surface states coexist with the insulating bulk.