Charge Transport Mechanisms in Two-Dimensional Materials

Two-dimensional materials, exemplified by graphene and transition metal dichalcogenides, exhibit unique charge transport phenomena arising from quantum confinement, reduced dielectric screening and atomically sharp interfaces. In these systems, carriers may traverse through ballistic regimes over micron-scale distances or experience diffusive scattering influenced by phonons, defects and substrate interactions. The formation of potential barriers at metal contacts and within heterointerfaces governs injection and extraction of charge, while precise tuning of carrier density via electrostatic gating or chemical doping enables control over conductivity and mobility. Interlayer coupling in van der Waals heterostructures further enriches transport by introducing novel band alignments and tunnelling pathways. Advances in fabrication—such as high-quality exfoliation, chemical vapour deposition and polymer encapsulation—have minimised extrinsic scattering, revealing intrinsic transport limits dictated by lattice vibrations and many-body effects. A deep understanding of these mechanisms underpins the development of next-generation electronics, including high-frequency transistors, ultrasensitive photodetectors and flexible sensors, where low power consumption, high on/off ratios and ambipolar conduction are paramount.

Research from Nature Portfolio

Recent studies have demonstrated that engineering the junction between graphene and a monolayer dichalcogenide can enhance carrier mobility by an order of magnitude without compromising switching performance. By electrostatically tuning the Fermi level in graphene, researchers have controlled the effective Schottky barrier height at the interface, revealing dual-hump transconductance features that illuminate the interplay between thermionic emission and tunnelling in two-dimensional junction field-effect transistors.

Foundational work has also introduced biomolecular nanostructures as ultra-low-level dopants for molybdenum and tungsten disulfide. By functionalising DNA scaffolds with selected metal and lanthanide ions, investigators achieved precise n- and p-type doping densities down to 10⁹ cm⁻². This method led to tunable barrier heights, significantly enhanced on-currents in transistors, and demonstration of improved photodetector responsivity via controlled charge injection at the two-dimensional channel.

Charge Transport Mechanisms in Two-Dimensional Materials publication trend

The graph below shows the total number of articles in charge transport mechanisms in two-dimensional materials across all publications each year (not limited to Nature Index journals).

Technical terms

Charge carrier mobility: Measure of how quickly electrons or holes move through a material under an electric field.

Schottky barrier: Energy barrier formed at a metal–semiconductor interface that affects carrier injection.

Field-effect transistor (FET): Device in which an electric field modulates the conductivity of a channel.

Charge transfer doping: Method of altering carrier density by transfer of electrons between a material and adsorbed species.

Van der Waals heterostructure: Stack of atomically thin layers held together by van der Waals forces, enabling custom band alignment.

Ballistic transport: Regime in which carriers propagate without scattering over characteristic device lengths.

References

1. High-mobility junction field-effect transistor via graphene/MoS2 heterointerface. Scientific Reports (2020).
2. Ultra-low Doping on Two-Dimensional Transition Metal Dichalcogenides using DNA Nanostructure Doped by a Combination of Lanthanide and Metal Ions. Scientific Reports (2016).
3. Controllable Carrier Doping in Two-Dimensional Materials Using Electron-Beam Irradiation and Scalable Oxide Dielectrics. Micromachines (2023).
4. Dipole doping effect in MoS2 field effect transistors based on phase transition of ferroelectric polymer dopant. Frontiers in Materials (2023).