Transparent thin film transistors by inkjet printing process

• Main Author: Myat Su Maung.
• Other Authors: Sun Xiaowei
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/46124
• Institution: Nanyang Technological University

Thin Film Transistor (TFT) technology has contributed to the advancement of the display industry for the past decades. Nowadays, TFT technology has been widely applied in Active Matrix Liquid Crystal Display (AMLCD) and Active Matrix Organic Light Emitting Diode (AMOLED), etc. Oxide semiconductors, such as Indium Gallium Zinc Oxide (InGaZnO), because of its large bandgap and excellent physical and chemical properties, offer an alternative as the channel layer material for transparent TFT. IGZO is transparent in the visible region due to the large band gap and has a high mobility, even for an amorphous structure due to s-electron conduction. High mobility is essential for current-driving devices such as organic light-emitting diodes and for building integrated electronics/drivers for system-on-glass. Although TFTs fabricated using magnetron sputtering, atomic laser deposition and pulse laser deposition techniques have shown good performance, their process cost is still very high. Therefore, inkjet printing method was attempted to achieve low cost, high performance IGZO based TFTs. In this project, bottom-gate, bottom-contact IGZO based TFTs have been fabricated, the active layer was deposited using inkjet printing and Indium Tin Oxide was sputtered as electrode. By varying the thickness of the active layer and annealing temperatures, the TFT fabricated can achieve a current on-off ratio of 9.625E+05, field effect mobility of 0.493cm2 /V.s and threshold voltage of -4.3V. In this report, the effect of channel layer thickness on the performance of IGZO based TFT, impact of annealing temperatures and passivation are studied and discussed.