Novel Crystals with Honeycomb Structure.
|Research Area||Materials Science|
|Principal Investigator(s)||Prof. Salim Ciraci|
Band structure of graphene, which is derived from its planar honeycomb structure leads to charge carriers resembling massless Dirac fermions with unusual properties. It has been questioned that whether materials like Si, Ge, GaAs, GaN etc having well developed microelectronic and optoelectronic technologies can form stable honeycomb structures, which may display properties similar to those of graphene. More recently, we showed that, in fact, Si and Ge can form stable and buckled honeycomb structure with linear bands crossing at the Dirac points, where electrons and holes have very high Fermi velocity and exhibit ambipolar effects. In this project we will elaborate the above prediction for novel applications where one can take advantage of all the expertise and technologies developed for Si, Ge, GaAs etc in several decades. Our project comprises following work packages: (i) Based on phonon and finite temperature ab-initio molecular dynamics calculations we will perform an extensive search for new materials forming honeycomb structures. These are, in addition to Si, Ge, other binary compounds of Group IV elements, III-V and II-VI compounds, specific metals and MX2 type materials, etc. (ii) We will examine whether new honeycomb structures form nanoribbons or nanobelts with different chiral angles. These nanoribbons are expected to have band gaps varying with their widths. Moreover specific nanoribbons may display magnetic properties depending on their chiral angle, and the passivation of their edges. Permanent magnetic moments can also be attained by specific vacancy defects. This situation provides us with complex quantum structures and superlattices showing the effects of multiple quantum wells or quantum dots, spin valves, etc. (iii) Finally, we will investigate the functionalization of honeycomb nanoribbons or sheets through geometry, adatom decoration, heterojunction formation and uniaxial plastic deformation for novel single and integrated spintronic devices and sensors. Project involves complex and high performance computations based on quantum mechanics with important applications in electronics, spintronics and biotechnology. In addition to large scale simulations, we will elaborate ab-initio, finite temperature molecular dynamics method as an efficient method to test the stability of nanostructures.