Reduced subthreshold swing in a vertical tunnel FET using a low-work-function live metal strip and a low-k material at the drain

Abstract

In this research paper, a vertical tunnel field-effect transistor (TFET) structure containing a live metal strip and a material with low dielectric constant is designed, and its performance metrics are analyzed in detail. Low-k SiO2 is incorporated in the channel–drain region. A live molybdenum metal strip with low work function is placed in a high-k HfO2 layer in the source–channel region. The device is examined by the parameters Ioff, subthreshold swing, threshold voltage, and Ion/Ioff ratio. The introduction of a live metal strip in the dielectric layer closer to the source–channel interface results in a minimum subthreshold slope and a good Ion/Ioff ratio. The low-k material at the drain reduces the gate-to-drain capacitance. Both the SiO2 layer and the live metal strip show excellent leakage current reduction to 1.4 × 10−17 A/μm. The design provides a subthreshold swing of 5 mV/decade, which is an excellent improvement in TFETs, an on-current of 1.00 × 10−5 A/μm, an Ion/Ioff ratio of 7.14 × 1011, and a threshold voltage of 0.28 V.

Keywords

• dual low-work-function live strip (dlwls)
• low-k dielectric spacer
• low-work-function live strip (lwls)
• miller capacitance
• molybdenum
• subthreshold swing (ss)
• tunnel field-effect transistor (tfet)