Carbon Nanotube Surface Engineering Through Supercritical CO₂ Pretreatment for High-Quality Gate Dielectric Deposition

Atomic layer deposition (ALD) has emerged as an important technique for dielectric fabrication in single-walled carbon nanotube field-effect transistors (SWCNT FETs). Notably, intrinsic SWCNTs are chemically inert and lack sufficient nucleation sites for the ALD process, which limits both the minimum thickness and interface quality of the dielectric layer. In this work, a pretreatment of SWCNTs with supercritical CO₂ (SCCO₂) fluids is introduced before ALD to improve the deposition quality. The SCCO₂ pretreatment SWCNTs (SC-SWCNTs) demonstrate an increased number of nucleation sites on the surface for ALD dielectric fabrication, thereby improving the quality of the deposited gate dielectric layer and effectively reducing the interface state density. The experimental results reveal that the SCCO₂-pretreatment SWCNT FET (SC-SWCNT FET) has an enhanced breakdown voltage of the dielectric layer and a reduction in interface state density, accompanied by a two-order-of-magnitude enhancement in the current on/off ratio. The SCCO₂ treatment demonstrates superior dielectric-SWCNTs interface modification capabilities, establishing a viable pathway for developing high-performance SWCNT FETs for next-generation nanoelectronics applications.