Giant Negative Differential Resistance Effect Caused by Cutting off Acceptable Quantum States in Carbon Nanotube Tunneling Devices

Tunneling devices with negative differential resistance (NDR) characteristic often suffer from bad peak-to-valley current ratios (PVR), which is due to the existence of the excess current generated by trap-assisted tunneling and phonon-assisted tunneling. How to suppress the excess current and improve PVR is a great challenge. Here, the authors propose a new strategy to suppress the excess current through cutting off the acceptable quantum states, and verify this mechanism by constructing a novel four-terminal tunneling device, which consists of the carbon nanotube as channel, Pd and Sc electrode for p-type and n-type Ohmic contact, respectively, and self-aligned split dual gates that modulate the channel to form the tunneling junction. In such a device, the window of acceptable quantum states can be cut off by increasing the sweeping rate ratio between the gate voltage to the drain voltage, so that the excess current can be suppressed. The devices exhibit significant NDR characteristics with a giant PVR of 13 500 at room temperature, and the peak current density can be up to 7 x 10(4) A cm(-2), both of which are the highest values among all the reported low-dimensional tunneling devices.