Band bending engineering in p-i-n gate all around Carbon nanotube field effect transistors by multi-segment gate

The p-i-n carbon nanotube (CNT) devices suffer from low ON/OFF current ratio and small saturation current. In this paper by band bending engineering, we improved the device performance of p-i-n CNT field effect transistors (CNTFET). A triple gate all around structure is proposed to manage the carrier transport along the channel. We called this structure multi-segment gate (MSG) CNTFET. Band to band tunneling (B-B tunneling) is a dominant transport mechanism in p-i-n structures which is more controlled here by band bending engineering. Gate metal at source side causes more bands bending at channel to source interface and the gate metal at drain side acts as a filter which reduces the leakage current. Results demonstrate that by parameter engineering of gate metal, the proposed structure improves the saturation current, leakage current, current ratio, subthreshold swing, breakdown voltage and cut-off frequency in comparison with conventional structure. Also, to obtain the optimum parameters, design considerations has been done in terms of difference in workfunctions and change in the length of each part of gates. Simulations and comparisons have been performed using none equilibrium Green's function and self-consistent solution between Poisson and Schrodinger equations.

Keywords:

Current Ratio , Cut-off Frequency , Leakage Current , MSG-T-CNTFET , NEGF , Saturation Current , Subthreshold Swing