Molybdenum sulphide as a competitor to silicon and graphene

MoS2 belongs to the family of layered transition metal dichalcogenides, which are particularly interesting in the field of nanoelectronics and optoelectronics. While graphene sheets are expected to be scalable beyond the current limits of conventional charge-based computer systems, MoS2 with a large band gap and with high mechanical stability, stands out as a serious alternative competitor to graphene for replacing silicon in next-generation field effect transistors.

The successful fabrication of atomic layers of MoS2 in the form of nanosheets, nanotubes and even thin films has further triggered research interest in their rich electronic and magnetic properties. With tuned magnetism, two-dimensional MoS2 structures are expected to open up further possible applications in next-generation spintronics devices.

Edge-dependent properties in MoS2 nanoribbons

We find a significant tweak in the edge-dependent electronic and magnetic properties of MoS2 nanoribbons when the ribbon edges are passivated with hydrogen and carbon atoms in different ways. Our first-principles calculations predict that zig-zag type ribbons of different widths will be metallic and ferromagnetic.

Furthermore, with one edge H passivated, the net magnetic moment of the ribbon increases. In contrast with both edges H passivated, the magnetic moment rather decreases when compared with the pristine ribbon. Interestingly, with C passivation the trend in the magnetic moment changes is the reverse. These different trends in the change in magnetic moment are attributed to the hybridization between Mo and the passivating elements H and C.

Nanoribbons modeled with an armchair type of edge are found to be non-magnetic and semiconducting. We find that the band gap of arm-chair-type nanoribbons increases when both sides are passivated with H and C compared with when just one side is passivated.

The results may have applications in the development of alternative computing systems and next-generation spintronics. We are now planning to contact experimental groups to synthesize these materials.

More information about the research can be found in the journal Nanotechnology 25 165703.

Further Reading

Going it alone: new dichalcogenide behaves like a monolayer (Feb 2014)
Band tail states appear in MoS2 (Jan 2014)