Nanocrystalline ZnO films prepared by Pulsed Laser Deposition were used to fabricate the first thin film transistors that operate at microwave frequencies. Unlike more conventional amorphous Si and organic thin film transistors, which are only suitable for low speed applications, ZnO-based thin film transistors exhibit figure-of-merit device numbers that are comparable to single crystal transistors. These include on/off ratio of 10¹², current density of >400mA/mm and field effect mobility of 110 cm²/V.s. Parameters, including film growth temperature, gate insulators, and device layout designs were examined in detail to maximize performance. We have achieved current gain cut-off frequency, f_T, and power gain cut-off frequency, f_max, values of 2.9GHz and 10GHz, respectively with 1.2μm gate length devices demonstrating that ZnO-based TFTs are suitable for microwave applications.

Date Published: 5 May 2010
PDF: 12 pages
Proc. SPIE 7679, Micro- and Nanotechnology Sensors, Systems, and Applications II, 767904 (5 May 2010); doi: 10.1117/12.849666

Published in SPIE Proceedings Vol. 7679:
Micro- and Nanotechnology Sensors, Systems, and Applications II
Thomas George; M. Saif Islam; Achyut Kumar Dutta, Editor(s)