Abstract
To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. We model transistors made of two-dimensional topological insulator ribbons accounting for scattering with phonons and imperfections. In the on-state, the Fermi level lies in the bulk bandgap and the electrons travel ballistically through the topologically protected edge states even in the presence of imperfections. In the off-state the Fermi level moves into the bandgap and electrons suffer from severe back-scattering. An off-current more than two-orders below the on-current is demonstrated and a high on-current is maintained even in the presence of imperfections. At low drain-source bias, the output characteristics are like those of conventional field-effect transistors, at large drain-source bias negative differential resistance is revealed. Complementary n- and p-type devices can be made enabling high-performance and low-power electronic circuits using imperfect two-dimensional topological insulators.
Highlights
To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering
8 10 y the energies Ej(k) and the ribbon wavefunctions fakjðyÞ, where k denotes the momentum along the ribbon transport direction and a is an index running over the four degrees of freedom of the BHZ Hamiltonian
We have modelled field-effect transistors (FETs) using topological insulators (TIs) ribbons as active channel material by solving the Boltzmann equation accounting for ballistic transport and scattering while respecting Pauli’s exclusion principle
Summary
To overcome the challenge of using two-dimensional materials for nanoelectronic devices, we propose two-dimensional topological insulator field-effect transistors that switch based on the modulation of scattering. To obtain the best possible electrostatic control in electronic devices such as field-effect transistors (FETs), twodimensional (2D) materials have to be used[1] In practice this is proving to be very challenging. For example, the effect of spin–orbit coupling can be safely ignored[27] whereas in stanene[28,29] (tin in a hexagonal monolayer configuration), spin–orbit coupling opens a bandgap of 0.17 eV which is much larger than the thermal energy at room temperature Some of these materials like stanene, functionalized stanene, transistion metal dichalcogenides in the distorted tetragonal phase[30], ZrTe5 (refs 31,32), bismuthene[33] and several other proposed materials, are 2D topological insulators (TIs)[34,35]. For transistor applications 3D TIs have severe disadvantages: a 3D TI will inevitably suffer from shunting paths through the bulk and through surfaces other than the surface on which the device is fabricated; the surface states of 3D TIs are effectively metallic making it hard to significantly move the Fermi level; and while the 3D TI surface states are spin-polarized, making them possible candidates for spin-based memory devices, conduction is not ballistic in 3D surface states
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