EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Single silicon nanowire (SiNW) omega-gate Field Effect Transistors (FETs) and resistors have been fabricated using the standard photolithography method on a Kapton flexible polyamide thin film attached to a sacrificial Silicon substrate. SiNWs have been grown by chemical vapor deposition (CVD) method using Vapour-Liquid-Solid (VLS) mechanism and gold as a catalyst. We developed a robust process of nanostructure integration onto flexible/rigid hybrid substrate constituted by Kapton on silicon. This flexible/rigid hybrid substrate can sustain temperatures as high as $400°C$, allowing the formation of low resistive nickel silicide at the source/drain contacts, contrary to the previously reported integration process on flexible substrates [1]. As a consequence, our SiNW-FETs can exhibit excellent electrical properties such as $22cm^2V^{-1}s^{-1}$ hole mobility, $10^5$ $I_{ON}$-to-$I_{OFF}$ ratio, and a subthreshold slope of about $340mV/dec$. These parameters can compete with those of organic transistors or in some aspects even exceeding electrical parameters of similar single SiNW transistors fabricated onto flexible substrates. Interestingly, after detachment of the sacrificial Si substrate, flexible devices on Kapton show improvement of their performance, and high stability over time and under small flexion was observed for both single nanowire transistors and resistors. Thus, by offering high chemical and thermal stability, as well as preserving good electrical features and even improve them upon detachment, this integration process based on flexible/rigid hybrid substrate may pave a way for the integration of further nanostructures [2].

[1] G. Rosaz, et al, Semiconductor science and technology 26 (8) (2011) 085020.

[2] T. T. T. Nguyen, et al, Nano Futures 3 (2) (2019) 025002.