Maskless Patterning of Low-Temperature High-Mobility ZnO

Abstract

ZnO is a material that has gained a great deal of interest in the low-temperature fabrication of high-mobility transistors. For rapid prototyping of device structures, as well as cycle time reduction for investigations of processing/geometry interactions, a maskless process with high spatial accuracy is desired. High-mobility ZnO transistors were fabricated on glass using a laser-thermal-based maskless patterning process to generate working circuits. All deposition temperatures were below 200 °C, allowing this process to be compatible with polymeric supports. A variety of circuits using 5 μm design rules and various channel width and length dimensions (w/l) were fabricated and analyzed. The circuits demonstrated included ring oscillators and logic circuits, such as an exclusive OR made from NANDs and NORs. The ring oscillator frequency was demonstrated to be about 20 kHz at 20 V. An active-matrix backplane was fabricated and used to drive an OLED device. The operating characteristics of the transistors, circuits, and processes were found to be interrelated and need to be co-optimized for the best performance.