Scalable and selective N-type conversion for carbon nanotube transistors via patternable polyvinyl alcohol stacked with hydrophobic layers and their application to complementary logic circuits

Abstract

Herein, this study reports scalable and selective n-type conversion (N/C) approach for single walled carbon nanotube (SWNT) transistors with high reproducibility by using novel control of hydroxyl groups through condensation on the surface of SWNTs, via the patternable cross-linked polyvinyl alcohol (C-PVA), followed by encapsulation of photo-definable hydrophobic polymer (~SU8). Moreover, N/C process capability is statistically evaluated in terms of selective doping, process yield, and statistical variation in electrical parameters, and as practical validation, complementary inverters, NOR and NAND logic gates are fully demonstrated. As one of key findings, it is elucidated that N/C uniformity and its underlying physics, supported by Fourier-transform infrared spectroscopy (FTIR) and Raman analysis, are highly correlated with ambient condition, C-PVA thickness, and encapsulation. More practically, reproducible field effect mobility for n-type (or p-type) SWNT TFTs after (or before) N/C are achieved at ~ 3.65 ± 1.30 (or 8.76 ± 2.16) cm2 V−1 s−1, with magnificent process yield (~100%) and reasonable mobility reduction, which is on par with the previous report. Hence, all demonstration and their analyses suggest that this scalable N/C scheme for SWNT TFTs can be one of core technologies for the next generation semiconductor-based devices and their envisioned application.