Bandstructure computation and investigation of resonant tunneling in nanoscale Schottky field effect transistor via sp3d5s* tight binding approach and non-equilibrium Green's function formalism

Abstract

In this paper, the electrical characteristics and resonant tunneling phenomenon in nanoscale double gate field effect Schottky transistor with InP (Indium Phosphide) as the channel material is investigated via non-equilibrium Green's function formalism. Unlike the conventional field effect transistor with doped source/drain, Schottky transistor possesses metallic source/drain regions and direct tunneling from source to channel is the main current mechanism of this device. The bandstructure of double gate device is calculated based on sp3d5s* tight binding approach employing thickness dependant two dimensional Hamiltonian. Reducing the channel thickness results in the increment of the carrier effective mass and shift of energy of subbands to higher values, in comparison with the related bulk values. In addition, by scaling down the channel thickness, gate control over the channel is enhanced that results in the improvement of the device electrical characteristics. Next, due to the increment of the effective Schottky barrier that is originated from quantum effects, a quantum well profile is created along the channel length from source to drain at low drain voltages. In this situation and for reduced values of temperature, resonant tunneling occurs in the proposed device. Different physical and structural parameters that may affect resonant tunneling are thoroughly investigated.