Effect of Humidity on the Breakdown of Carbon Nanotube Network Thin Film Transistors

Abstract

Carbon nanotube network thin-film transistors (CNN TFTs) have great potential in macroelectronic applications as they have excellent electromechanical properties. Particularly, they have applications in flexible electronics such as displays due to their transparency and high mobility as compared to organic TFTs. As their applications are developed further, it becomes important to study their reliability at high electric fields, which is the purpose of this study. The relation between breakdown voltage of CNN TFTs and ambient humidity level is also studied, which could be important for sensors as well as electronics operation. Since there are many sources of oxygen for the CNN TFTs to come in contact with, it is difficult to predict, a priori, whether humidity plays a significant role in the breakdown. In this experiment, CNN TFTs of lengths 10 µm and 15 µm were broken down in the "ON" mode at humidity levels of 10%, 40% and 70%. A significant decrease in breakdown voltages was observed going from humidity level of 10% to 40% for both lengths. However, the change was negligible between the humidity levels of 40% and 70%. The breakdown mechanism and possible explanation for such behavior of the breakdown voltage reaching saturation as a function of increasing humidity level are explored.