Improved Electrical Properties of Zinc-Tin Oxide TFTs by Inkjet Process Optimization

Inkjet printing process was optimized to improve the electrical properties of inkjet-printed zinc-tin oxide thin-film transistors. Among the process conditions evaluated, inkjet voltage and substrate temperature were found to be the key factors for obtaining uniform thin-films and good thin-film transistors. The optimization process with a jetting voltage of 60 V and substrate temperature of 50 degrees C gave good electrical properties, such as a field-effect mobility of 5.11 cm(2)/V s, a threshold voltage of 2.83 V, a subthreshold slope of 1.33 V/dec, and an on-to-off current ratio of 10(8). The electrical properties of the inkjet-optimized TFTs were superior to those of the unoptimized inkjet TFTs. A positive bias stability was also investigated.