Investigation of Tunneling Effect for a N-Type Feedback Field-Effect Transistor

In this paper, the tunneling effect for a N-type feedback field-effect transistor (NFBFET) was investigated. The NFBFET has highly doped N-P junction in the channel region. When drain-source voltage is applied at the NFBFET, the aligning between conduction band of N-region and valence band of P-region occur, and band-to-band tunneling (BTBT) current can be formed on surface region of N-P junction in the channel of the NFBFET. When the doping concentration of gated-channel region (N-gc) is 4 x 10(18) cm(-3), the tunneling current makes off-currents increase approximately 10(4) times. As gate-source voltage is applied to NFBFET, the tunneling rate decreases owing to reducing of aligned region between bands by stronger gate-field. Eventually, the tunneling currents are vanished at the BTBT vanishing point before threshold voltage. When N-gc increase from 4 x 10(18) to 6 x 10(18), the tunneling current is generated not only at the surface region but also at the bulk region. Moreover, the tunneling length is shorter at the surface and bulk regions, and hence the leakage currents more increase. The BTBT vanishing point also increases due to increase of tunneling rates at surface and bulk region as N-gc increases.

Automated summary

This study investigated the tunneling effect in a N-type feedback field-effect transistor (NFBFET). The NFBFET has a highly doped N-P junction in the channel region, and when a drain-source voltage is applied, band-to-band tunneling (BTBT) current can be formed on the surface region of the N-P junction. The alignment between the conduction band of the N-region and the valence band of the P-region occurs, resulting in an increase in off-currents. However, as a gate-source voltage is applied, the tunneling rate decreases due to a reduction in the aligned region between bands caused by a stronger gate-field. The tunneling currents eventually vanish before reaching the threshold voltage at the BTBT vanishing point. Increasing the doping concentration in the gated-channel region results in the generation of tunneling current not only on the surface region but also in the bulk region, leading to shorter tunneling lengths and increased leakage currents. The BTBT vanishing point also increases as the tunneling rates at the surface and bulk regions increase.