Analysis of Current Variation with Work Function Variation in L-Shaped Tunnel-Field Effect Transistor

Jang Hyun Kim; Hyun Woo Kim; Young Suh Song; Sangwan Kim; Garam Kim

doi:10.3390/mi11080780

Analysis of Current Variation with Work Function Variation in L-Shaped Tunnel-Field Effect Transistor

Micromachines (Basel). 2020 Aug 15;11(8):780. doi: 10.3390/mi11080780.

Authors

Jang Hyun Kim¹, Hyun Woo Kim², Young Suh Song^{2

3}, Sangwan Kim⁴, Garam Kim⁵

Affiliations

¹ School of Electrical Engineering, Pukyong National University, Busan 48513, Korea.
² Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea.
³ Department of Computer Science, Korea Military Academy, Seoul 01805, Korea.
⁴ Department of Electrical and Computer Engineering, Ajou University, Suwon 16499, Korea.
⁵ Department of Electronic Engineering, Myongji University, Yongin 17058, Korea.

Abstract

In this paper, an investigation is performed to analyze the L-shaped tunnel field-effect transistor (TFET) depending on a gate work function variation (WFV) with help of technology computer-aided design (TCAD) simulation. Depending on the gate voltage, the three variations occur in transfer curves. The first one is the on-state current (I_ON) variation, the second one is the hump current (I_HUMP) variation, and the last one is ambipolar current (I_AMB) variation. According to the simulation results, the I_ON variation is sensitive depending on the size of the tunneling region and could be reduced by increasing the tunneling region. However, the I_HUMP and I_AMB variations are relatively irrelevant to the size of the tunneling region. In order to analyze the cause of this difference, we investigated the band-to-band tunneling (BTBT) rate according to WFV cases. The results show that when I_ON is formed in L-shaped TFET, the BTBT rate relies on the WFV in the whole region of the gate because the tunnel barrier is formed in the entire area where the source and the gate meet. On the other hand, when the I_HUMP and I_AMB are formed in L-shaped TFET, the BTBT rate relies on the WFV in the edge of the gate.

Keywords: L-shaped TFET; ambipolar current (IAMB) variation; band-to-band tunneling; high-κ/metal gate (HKMG); hump current (IHUMP) variation; on-state current (ION) variation; tunnel field-effect transistor (TFET); work-function variation (WFV).