Implementation of a Linearly Graded Binary Metal Gate Work Function VTFET with Air Pocket

Authors K. Kalai Selvi1 , K.S. Dhanalakshmi2

1Government College of Engineering, Tirunelveli, Tamil Nadu, India

2Kalasalingam Academy of Research and Education, Virudhunagar, Tamil Nadu, India

Issue Volume 14, Year 2022, Number 6
Dates Received 20 September 2022; revised manuscript received 20 December 2022; published online 27 December 2022
Citation K. Kalai Selvi, K.S. Dhanalakshmi, J. Nano- Electron. Phys. 14 No 6, 06014 (2022)
PACS Number(s) 85.30.Tv
Keywords Tunnel FET (2) , Linearly-graded structure, Subthreshold swing (SS), Vertical TFET, Transconductance generation efficiency.

In the present paper, the linearly graded work function (LG-W) characteristics are explored by using binary metal alloy aσb1 – σ gate electrode composition in a high-k gate stack with a dielectric pocket in vertically aligned TFET (VTFET). The VTFET device is constructed using a binary metal alloy gate electrode with a linearly graded work function and an air pocket. The proposed structure performance metrics are evaluated and compared to the state-of-the-art. The integration of LG-W with gate-stack VTFET along with air pocket, namely SG-LG-VTFET with air pocket, reveals performance improvement via metrics such as device ON-current (ION), subthreshold swing (SS), transconductance (gm) as well as transconductance generation efficiency (TGE). SG-LG-VTFET with air pocket generates SS of 13.92 mV/dec. Further, the device exhibits a higher ION (3.6x10 – 5 A/µm) with an ION/IOFF ratio of 1012. Due to the inclusion of the LG-W and air pocket, a narrow band-bending is observed, thus resulting in higher tunneling and steeper SS. A high-k stacked dielectric material enhances the capacitive coupling. The performance of the device is compared with the VTFET device in the absence of a dielectric pocket. The dielectric pocket increases the electric field, which is a desirable phenomenon for increasing the ON-current. For future applications, the scaling in SS is further possible that can increase the electron tunneling rate.

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