Based on the approximated solution of Poisson's equation, we propose a continuous current model of ultra-thin fully depleted cylindrical surrounding-gate Si nanowire MOSFETs. It matches well with three-dimensional simulation results using SILVACO Atlas TCAD in a wide range (from intrinsic to high doping) of the body doping concentration without any empirical fitting parameters. It is valid for all the operation regions such as subthreshold, turn-on, linear and saturation.

Abstract-The effect of band-to-band tunneling (BTBT) leads to an obvious increase of the leakage current of junctionless (JL) transistors in the OFF state. In this paper, we propose an effective method to decline the influence of BTBT with the example of ntype double gate (DG) JL metal-oxide-semiconductor field-effect transistors (MOSFETs). The leakage current is restrained by changing the geometrical shape and the physical dimension of the gate of the device. The optimal design of the JL MOSFET is indicated for reducing the effect of BTBT through simulation and analysis.

No abstract

An analytical subthreshold current of deep nanoscale short channel junctionless field-effect transistors (JL FETs) with a symmetric double-gate (DG) structure has been proposed. It is derived from two-dimensional Poisson's equation using a variable separation technique. The proposed models can exactly describe the behaviour of subthreshold I–V characteristics with nanoscale channel length without any empirical fitting parameter. The model accounts for channel length, body thickness, gate oxide thickness and body doping concentrations. The models are verified by comparison with TCAD simulations and show good agreement.

Our previous research work indicated that highly boron doped polysilicon nanofilms (≤100 nm in thickness) have higher gauge factor (the maximum is ∼34 for 80 nm-thick films) and better temperature stability than common polysilicon films (≥ 200nm in thickness) at the same doping levels. Therefore, in order to further analyze the influence of deposition temperature on the film structure and piezoresistance performance, the piezoresistive sensitivity, piezoresistive linearity (PRL) and resistance time drift (RTD) of 80 nm-thick highly boron doped polysilicon nanofilms (PSNFs) with different deposition temperatures were studied here. The tunneling piezoresistive model was established to explain the relationship between the measured gauge factors (GFs) and deposition temperature. It was seen that the piezoresistance coefficient (PRC) of composite grain boundaries is higher than that of grains and the magnitude of GF is dependent on the resistivity of grain boundary (GB) barriers and the weight of the resistivity of composite GBs in the film resistivity. In the investigations on PRL and RTD, the interstitial-vacancy (IV) model was established to model GBs as the accumulation of IV pairs. And the recrystallization of metastable IV pairs caused by material deformation or current excitation is considered as the prime reason for piezoresistive nonlinearity (PRNL) and RTD. Finally, the optimal deposition temperature for the improvement of film performance and reliability is about 620 °C and the high temperature annealing is not very effective in improving the piezoresistive performance of PSNFs deposited at lower temperatures.