There are certain major characteristics that are desirable for multifunctional electronic like scaling and sensing among others. The most desirable are ultrathin semiconductors with surfaces that are atomically smooth. So far, the desired material is a 2D material with same characteristics as those of Graphene but with reasonably large bandgap.A Graphene has one atomic layer thick, it is flexible, it is mechanically strong, it has chemical inert, it has thermal stability and has high mobility. The only characteristic it lacks to make it a highly desirable multifunctional electronic is the presence of bandgap as Graphene has no bandgap.So far Transition Metal Dichalcogenides (TMD) have emerged as a promising semiconductor materials that can complement graphene.TDM has a bandgap of 1-2eV, it is thin with a uniform channel, it has smooth surfaces, it is thermally stable and has reasonably good mobility.TMD has provided some of these characteristics in early works of field effects. Just like graphene TMD have shown highly tunable properties based on layer count and top gate materials.In particular,MoS2 which contain much bulk of the material has a reasonably larger bandgap and modest electron mobility.
The good contact materials that form an electrical contact to 2D semiconductors exhibit some key characteristics. They include high conductivity, chemical and thermal stability, high density of delocalized states across the interface at the Fermi level, low Schottky barrier and strong bonding. The strategies for making a low resistance contact include lowering the Schottky barrier weight and reducing its width and reducing the tunnel barrier. There are various approaches for making a good conductor. The first approach is thinning the Schottky barriers thickness with an ionic liquid gating to MoS2 contact. The results for this approach however still gives rise to a large tunnel barrier. The second approach is making good conduct to WSe2 by tuning the WSe2 work function as a tunable electrode material. Back-gated WSe2 and monolayer FETs with surface doping have proved to be highly mobile in the field effect. Also, an intrinsic hole mobility of up to 400 cm2v-1s-1 is also observed in fields effect of WSe2.The disadvantage, however, is the tendency of forming a substantial Schottky barrier by WSe2 in the development of WSe2 based electronic devices. This a big disadvantage because most metals are commonly used for making electrical contacts, and low resistance ohmic contacts are one that provides transport properties and performance limits.
The disadvantages presented by the already tested approaches leads us to the continued search for new contacts. The materials in search are those that have air stability, thermal stability, true-ohmic contact and have contact resistance. Silicon based electrons done on MOSFET working principle seems to be a modernized approach.MOSFET oxidizes a semiconductor in the in transmission in field effect. To fabricate graphene,WSe2 can be produced in bulk and transferred onto degenerated dopes silicon electrodes.Graphene transfer method developed is a dry process which has the ability to transfer large area, voidless and metal catalyzed graphene films into surfaces including silicon oxide. This process uses thermal release tape to remove graphene layers from the substrate. The Graphene is then pressed onto the substrate of interest which in our case is silicon electronics, and adhesion strength removed through a thermal process.WSe2 channel with degenerated p-doped WSe2 contacts improves the 2-termional FE mobility as the quality of channel material improves.