Simulated THz response spectrum of a multi-gate GaAs nanowire FET (channel diameter=20nm, length=600nm, gate oxide=10nm, 4 electrons).
So far, common characterization methods for FETs involve signal frequencies from DC up to 100 GHz. However, typical energy scales of quantized states in realistic nanowire FETs are on the order of a few meV corresponding to the THz frequency range. We therefore propse signals in the THz regime to directly probe quantum transitions between few-electron states within a nanowire FET. For the first time, we have simulated the intra-band THz response of such devices by means of a novel many-body quantum approach (BBCI) [1,2], taking quantization and few-electron Coulomb interaction effects beyond mean-field into account. Combining this spectroscopic approach with a multi-gate design , we obtain spatially resolved information about the electronic spectra inside the FET, far beyond the limitations of standard characterization methods.
The figure shows a schematic sketch of the considered nanowire FET with multiple gate segments and the THz spectrum of a realistic example. Such a spatially resolved spectrum can be interpreted as a fingerprint of the concrete electronic structure, which might prove useful in future experimental realizations as a means to characterize nanoscale devices for information technology.
 cond-mat/0609540 (2006)
 Phys. Rev. B 77, 125436 (2008)