Novel structures and materials, such as ultra-scaled Si MOSFETs, multiple gate MOSFETs, carbon nanotube FETs, and molecular-based transistors, are expected to be introduced to meet the requirements for scaling. A deep understanding of quantum effects in nanoelectronic devices helps to improve the functionality of devices and to develop new device types. For this purpose, further theoretical and experimental research has to be performed which requires an extensive use of computer simulation.
The Non-Equilibrium Green's Functions (NEGF) have been successfully used to investigate the characteristics of nanoscale silicon transistors, carbon-nanotube-based transistors, and molecular devices. Using the NEGF formalism, quantum phenomena, like tunneling and scattering processes, can be rigorously modeled. With the aid of this formalism we investigated the behavior of carbon nanotube transistors.
The effect of the scaling of the gate-source and gate-drain spacer lengths on the device response was investigated for different barrier heights at the metal-nanotube interface. Electron-phonon interaction parameters, such as electron-phonon coupling strength and phonon energy, strongly depend on the chirality and the diameter of the carbon nanotube. The steady-state and dynamic response of carbon-nanotube-based transistors have been studied for a wide range of electron-phonon interaction parameters. Based on the results, methods for improving the performance of nanotube transistors have been proposed.