Solution-Processed IGZO/CNTs Composite Thin Film Transistors for Megahertz Application

Abstract

Thin film transistors (TFTs) have broad applications for flexible electronics and information display.1 With excellent transparency, high stability, and low-temperature processes, amorphous metal oxide materials have drawn considerable attention for potential applications in transparent and flexible electronics, such as touch display panels. To date, most transparent TFTs have been fabricated with amorphous indium gallium zinc oxide (a-IGZO), zinc indium tin oxide, ZnO, In2O3, indium gallium zinc oxide, or some other oxide semiconductors as channel materials by the sol-gel route, with the performance approaching that of crystalline silicon based materials. Firstly, to implement flexible high-performance electronics, materials with a high carrier mobility and high flexibility are required. Through using a composite material structure consisting of single-walled carbon nanotube (SWNTs) embedded directly into the a-IGZO thin film via spin-coating process, which significantly improves electrical properties and mechanical behaviors of the thin films. In the composite, SWNTs supply the enhanced-current path for carrier transportation, and the contact resistance was optimized by incorporating SWNTs as well. The threshold voltage (Vth) is modulated by adjusting the Ga content. High electrical performance was demonstrated, including a field-effect mobility of 132 cm2/V·s and a Vth of 0.8 V. We have fabricated large-scale working devices with channel lengths from 20 μm down to 0.7 μm. Moreover, the devices were stable over time. These results indicate that a-IGZO/SWNTs composite TFTs strongly sustain further investigation of their applicability.