With the development of integrated circuit (IC) technology, the scaling of silicon-based metal oxide semiconductor (MOS) field-effect transistors (FETs) is approaching their fundamental physical limits. Carbon nanotubes (CNTs) are considered promising materials in the post silicon era due to their atomic thickness and unique electrical properties, with the potential to improve transistor performance while reducing power consumption. High purity aligned carbon nanotubes (A-CNT) are an ideal choice for driving advanced ICs due to their high current density. However, when the channel length (Lch) decreases below 30nm, the performance of single gate (SG) A-CNT FET significantly decreases, mainly manifested as deteriorating switching characteristics and increased leakage current. This article aims to reveal the mechanism of performance degradation in A-CNT FET through theoretical and experimental research, and propose solutions.

Academician Peng Lianmao, researcher Qiu Chengguang, and researcher Liu Fei from Peking University overcame the electrostatic coupling between carbon nanotubes (CNTs) through a double gate structure to achieve the Boltzmann switching limit of carbon nanotube transistors (CNT-FET). Research has found that high-density aligned carbon nanotubes (A-CNT) exhibit significant band gap narrowing (BGN) due to stacking in traditional single gate configurations, thereby affecting their inherent quasi one dimensional electrostatic advantages.

Through theoretical simulation and experimental verification, an effective dual gate structure has been proposed, which can significantly reduce the BGN effect, achieve the subthreshold swing (SS) of A-CNT FET to the Boltzmann thermal emission limit of 60mV/decade, and achieve a switching current ratio exceeding 10 ^ 6. In addition, the prepared 10nm ultra short gate A-CNT dual gate FET exhibits excellent performance such as high saturation current (over 1.8mA/μ m), high peak transconductance (2.1mS/μ m), and low static power consumption (10nW/μ m), meeting the requirements of advanced integrated circuits. The related research results were published in ACS Nano under the title "Realizing Boltzmann Switching Limit in Carbon Nanotube Transistors through Combining Intertube Electrostatic Coupling".

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