Design and Investigation of the Junction-Less TFET with Ge/Si0.3Ge0.7/Si Heterojunction and Heterogeneous Gate Dielectric

Tao Han,Ming Cai,Xiaoli Yang,Shupeng Chen,Kun Yang,Wei Li,Shulong Wang,Hongxia Liu

doi:10.3390/electronics8050476

Abstract

To improve the on-state current and reduce the miller capacitance of the conventional junction-less tunneling field effect transistor (JLTFET), the junction-less TFET with Ge/Si0.3Ge0.7/Si heterojunction and heterogeneous gate dielectric (H-JLTFET) is investigated by the Technology Computer Aided Design (TCAD) simulation in this paper. The source region uses the narrow bandgap semiconductor material germanium to obtain the higher on-state current; the gate dielectric adjacent to the drain region adopts the low-k dielectric material SiO2, which is considered to reduce the gate-to-drain capacitance effectively. Moreover, the gap region uses the Si0.3Ge0.7 material to decrease the tunneling distance. In addition, the effects of the device sizes, doping concentration and work function on the performance of the H-JLTFET are analyzed systematically. The optimal on-state current and switching ratio of the H-JLTFET can reach 6 µA/µm and 2.6 × 1012, which are one order of magnitude and four orders of magnitude larger than the conventional JLTFET, respectively. Meanwhile, the gate-to-drain capacitance, off-state current and power consumption of the H-JLTFET can be effectively suppressed, so it will have a great potential in future ultra-low power integrated circuit applications.

Highlights

The mechanism of traditional metal oxide semiconductor field effect transistors (MOSFETs) is thermal electron emission, so the subthreshold swing (SS) is limited to 60 mV/Dec at room temperature [1,2,3]
Switching ratio of by onetheand four on-state current and switching ratio of are increased by one and four orders of magnitude, orders of magnitude, respectively. The reason for this is that the Ge/Si0.3Ge0.7/Si heterojunction is respectively. The reason for this is that the Ge/Si0.3 Ge0.7 /Si heterojunction is formed in the channel of formed in the channel of H-junction-less tunneling field effect transistor (JLTFET), the energy bands can be bent more severely, and the band to band tunneling (BTBT)
The conventional JLTFET, the differences of the H-JLTFET are that the source region uses germanium

Summary

Introduction

The mechanism of traditional metal oxide semiconductor field effect transistors (MOSFETs) is thermal electron emission, so the subthreshold swing (SS) is limited to 60 mV/Dec at room temperature [1,2,3]. To solve the above problems, researchers have conducted extensive research on tunneling field effect transistors (TFETs) with steep SS characteristics. The TFETs is compatible with the Complementary Metal Oxide Semiconductor (CMOS) technology, which is not likely to be influenced by the short channel effect. It can break the SS limit of 60 mV/Dec, and the leakage current is small under the off-state condition [10].

Methods

Results

Conclusion