Transparent megahertz circuits from solution-processed composite thin films

Abstract

Solution-processed amorphous oxide semiconductors have attracted considerable interest in large-area transparent electronics. However, due to its relative low carrier mobility (∼10 cm² V⁻¹ s⁻¹), the demonstrated circuit performance has been limited to 800 kHz or less. Herein, we report solution-processed high-speed thin-film transistors (TFTs) and integrated circuits with an operation frequency beyond the megahertz region on 4 inch glass. The TFTs can be fabricated from an amorphous indium gallium zinc oxide/single-walled carbon nanotube (a-IGZO/SWNT) composite thin film with high yield and high carrier mobility of >70 cm² V⁻¹ s⁻¹. On-chip microwave measurements demonstrate that these TFTs can deliver an unprecedented operation frequency in solution-processed semiconductors, including an extrinsic cut-off frequency (f_T = 102 MHz) and a maximum oscillation frequency (f_max = 122 MHz). Ring oscillators further demonstrated an oscillation frequency of 4.13 MHz, for the first time, realizing megahertz circuit operation from solution-processed semiconductors. Our studies represent an important step toward high-speed solution-processed thin film electronics.