Vertical field-effect transistor based on graphene–WS2 heterostructures for flexible and transparent electronics

Abstract

The celebrated electronic properties of graphene have opened the way for materials just one atom thick to be used in the post-silicon electronic era. An important milestone was the creation of heterostructures based on graphene and other two-dimensional crystals, which can be assembled into three-dimensional stacks with atomic layer precision. Such layered structures have already demonstrated a range of fascinating physical phenomena, and have also been used in demonstrating a prototype field-effect tunnelling transistor, which is regarded to be a candidate for post-CMOS (complementary metal-oxide semiconductor) technology. The range of possible materials that could be incorporated into such stacks is very large. Indeed, there are many other materials with layers linked by weak van der Waals forces that can be exfoliated and combined together to create novel highly tailored heterostructures. Here, we describe a new generation of field-effect vertical tunnelling transistors where two-dimensional tungsten disulphide serves as an atomically thin barrier between two layers of either mechanically exfoliated or chemical vapour deposition-grown graphene. The combination of tunnelling (under the barrier) and thermionic (over the barrier) transport allows for unprecedented current modulation exceeding 1 × 10(6) at room temperature and very high ON current. These devices can also operate on transparent and flexible substrates.

Gate-Tunable Tunneling Resistance in Graphene/Topological Insulator Vertical Junctions

“…~4 K). This fitting result is quite consistent with the raw R-T curve, which shows a dramatic increase of R j below 4 K. At low temperatures (T < 4 K), the tunneling current is determined by the density of states (DOS) in the graphene (D G ) and in the Bi 2 Se 3 (D TI ), which can be expressed as 11,12,17,32 where T(E) is the tunneling probability and the function ( ) is the Fermi-Dirac distribution function. In the low temperature region, the integral energy can be restricted to the range between and + eV, where is the chemical potential.…”

“…In other words, R j is exponentially sensitive to the reciprocal of temperature. 12 Thus the Arrhenius plot of ln(R j ) vs 1/T is presented at high temperature (Figure 3b), giving ∆~0.35 meV (i.e. ~4 K).…”

Spectroscopic Signatures for Interlayer Coupling in MoS2–WSe2 van der Waals Stacking

“…TMDs, h-BN and graphene). [15][16][17][18][19][20][21] Such stacked heterostructures based on atomically thin 2D layers are fundamentally different since only van der Waals interactions exist at the interfaces. Therefore, these layered materials (termed also van der Waals solids) enable the preparation of high-quality heterointerfaces without the need of fulfilling an atomic commensurability 17,18,22 , thus making the structure construction easily achievable.…”

Independent Band Modulation in 2D van der Waals Heterostructures via a Novel Device Architecture

“…Recently, considerable research interest has been intrigued by the vertically stacked vdWs integration of various 2DLMs, which provides infinite possibilities by overcoming the limitation of lattice matching and processing compatibility 6, 7, 8, 9, 10, 11, 12, 13, 14. Among various categories of vertically stacked vdWs heterostructured devices, the tunneling field effect transistor (TFET), which provides a promising sub‐60‐mV dec −1 subthreshold swing (SS), has been regarded as a promising application of vdWs heterostructure for future energy‐efficient electronics 15, 16, 17, 18, 19…”