Development of High-Mobility Low-Temperature Solution-Processed Metal-Oxide Thin Film Transistors Grown by Spray Pyrolysis

Abstract

In today’s electronics, transistors are the main building blocks of the vast majority of electronic devices and integrated circuits. Types of transistors vary depending on the device structure and operation principle. Metal-oxide-based thin film transistors (MO TFTs), in particular, are an emerging technology that has a promising future in many applications, such as large-area display and wearable electronics. It exhibits unique features that make it superior to the existing Si-based technology, such as optical transparency and mechanical flexibility. However, some technical challenges in MO TFTs limit their emplyoment in today’s applications, such as low carrier mobility and high processing temperature. Solution-processed MO TFT based on spray pyrolysis combined with a carefully engineered TFT structure offers a dramatically enhance carrier mobility at low processing temperature. In this work, we are utilizing spray pyrolysis to grow In2O3 and ZnO based TFTs at low processing temperature. The structural effects of the channel layer on the electrical performance is investigated in two parts. The first part highlights the impact of thickness of the channel layer on the device performance of both In2O3 and ZnO, while the second part explores In2O3/ZnO heterojunction-based active layer. The results showed that increasing the channel thickness of both In2O3 and ZnO based TFTs enhanced the carrier mobility due to a reduced surface-roughness scattering effect. In addition, evidence showed that the electron transport mechanism in In2O3/ZnO heterojunction transitioned from trap-limited conduction (TLC) to percolation conduction (PC) process. Thanks to the existence of a 2D-confined electron sheet at the atomically sharp In2O3/ZnO heterointerface, the electron mobility was dramatically enhanced.