Impact of Dielectric Pocket on Analog and High-Frequency Performances of Cylindrical Gate-All-Around Tunnel FETs. (5th May 2018)

• Record Type: Journal Article
• Authors: Pandey, C. K.; Dash, D.; Chaudhury, S.
• Is Part Of: ECS journal of solid state science and technology. Volume 7:Number 5(2018)
• Page Start: N59
• Page End: N66
• Publication Date: 2018-05-05
• Subjects: Ambipolar conduction -- dielectric pocket -- tunnel FET; Solid state chemistry -- Periodicals; Electronics -- Materials -- Periodicals; Electrochemistry -- Periodicals; 541.0421
• DOI: 10.1149/2.0101805jss
• Languages: English
• ISSNs: 2162-8777

Abstract

Abstract : In this paper, a novel structure of cylindrical GAA-TFETs with high- k dielectric pocket is proposed to improve the analog and high-frequency performances. We have discussed the device physics of proposed structure in details with the help of 3-D TCAD simulation. Since, an optimum part of the drain region is replaced with a high- k dielectric material (HfO2 ), oxide-semiconductor interface formed between channel and dielectric pocket increases the tunneling width at channel-drain junction. Further, this increment in tunneling width caused by depleted drain region under dielectric pocket eventually reduces the ambipolar conduction and OFF-current without deteriorating ON-current and subthreshold slope. It is observed that device performances are improved with increasing pocket length and thickness up to a value of 30-nm and 4-nm respectively; beyond which either device performances are degraded or dependences become poor. The advantages of using a high- k dielectric material over low- k are demonstrated in terms of reduction in ambipolar conduction, and immunity against degradation in current switching ratio during device scaling. Additionally, the impact of high- k dielectric pocket on high-frequency performances is demonstrated. Unlike tunnel FETs with dielectric spacer, it is observed that drain-to-gate capacitance is reduced for our proposed device which further leads to improvement in cutoff frequency.