Three-Dimensional-Topological-Insulator Tunnel Diodes

Topological insulators (TIs) open up many avenues for designing future electronic devices. Using the Bardeen transfer Hamiltonian method, we calculate the current density of electron tunneling between two slabs of $\mathrm{Bi}$${}_{2}$$\mathrm{Se}$${}_{3}$. We calculate the three-dimensional TI tunnel-diode current-voltage (J-V) characteristics for different doping concentrations, tunnel-barrier heights and thicknesses, and 3D-TI band gaps. The difference in the Fermi levels of the slabs determines the peak and valley voltages. The tunnel-barrier width and height affect the magnitude of the current without affecting the shape of the $J$-$V$ characteristics. The band gap of the 3D TI determines the magnitude of the tunnel current, albeit at a lesser rate than the tunnel-barrier potential; thus the device characteristics are robust under changing TI material. The high peak-to-valley ratio of 3D-TI tunnel diodes, the controllability of the valley-current location, and the simple construction provide advantages over other negative-differential resistance devices.