Microwave TFTs Made of MOCVD ZnO With ALD Al₂O₃ Gate Dielectric

Abstract

In this paper, we report on the demonstration of microwave ZnO thin-film transistors (TFTs) grown by metal organic chemical vapor deposition (MOCVD) on a SiO2/Si substrate. In order to realize the microwave performance ZnO TFTs grown by MOCVD, the inverted staggered type device structure and the high quality Al2O3 gate dielectric layer grown by atomic layer deposition were employed. ZnO TFTs show the depletion mode operation and exhibit an on/off drain current ratio of 6.7 × 106, a peak transconductance of 124 μS, and a field-effect mobility (μFE) of 23.3 cm2/V·s, respectively. As a result of excellent dc performance, a cut-off frequency (fT) of 0.73 GHz and a maximum oscillation frequency (fmax) of 2 GHz were achieved.

Keywords

• ZnO TFT
• microwave
• ALD dielectric