Controllable doping and passivation of ZnO thin films by surface chemistry modification to design low-cost and high-performance thin film transistors

Solution-processed metal oxide thin-film transistors have become more popular as they can be used to fabricate transparent and flexible electronics at low cost. However, additional and complex processes for trap-site passivation and doping hinder the potential of the low-cost solution process. This study introduces a surface passivation process involving treatment with 3-aminopropyltriethoxysilane (APTES) that can enhance the electrical properties of ZnO sol-gel thin films. Optical, chemical, and structural analyses of ZnO sol-gel thin films revealed that their trap sites were passivated successfully through APTES treatment under basic conditions. Taking advantage of this process, high-mobility and negligible-hysteresis ZnO thin-film transistors were successfully fabricated, showing an I-on/I-off of 10(5), hysteresis as low as 1.13 V, and mobility of up to 0.117 cm(2)/Vs. Furthermore, a characteristic transition of ZnO sol-gel thin films from semiconductive to semimetallic was observed during investigations with various APTES concentrations.