Local Volume Depletion/Accumulation in GAA Si Nanowire Junctionless nMOSFETs

In this paper, we report, for the first time, corner effect analysis in the gate-all-around equilateral triangular silicon nanowire (NW) junctionless (JL) nMOSFETs, from subthreshold to strong accumulation regime. Corners were found to accumulate and deplete more electrons than the flat sides or the channel center, when above (local accumulation) and below (local depletion) the flat-band voltage, respectively. On the contrary to the corner effect in the inversion mode (IM) devices, there is no major contribution of corners in the subthreshold current, and therefore, there is no subthreshold device behavior degradation (only one threshold voltage in the system). N-type channel doping levels of 1 × 10¹⁹, 5 × 10¹⁸, and 1 × 10¹⁸ cm^-3 were used for quasi-stationary device simulations of JL and AM MOSFETs, and corner effect was studied for 5, 10, and 15 nm wide equilateral triangular Si NW MOSFETs with a 2 nm SiO₂ gate oxide thickness (V_DS = 0 V; T = 300 K). While the local quantum and classical electron density peaks are located in the corner regions above the flat-band voltage, reducing the channel doping and the channel cross-section was found to slightly suppress the normalized total accumulation electron density per unit length, N_t^acc/(CW_eff), in strong accumulation regime.