Ultra-thin-film transistors based on ultra-thin amorphous ZnSnO films
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Ultra-thin amorphous ZnSnO (a-ZTO) films were deposited by pulsed laser deposition at room temperature and annealed at various temperatures for ultra-thin-film transistors (UTFTs). The thicknesses of the ultra-thin a-ZTO films are approximately 3.1 nm. The electrical resistivity of the nanofilms decreases greatly with the annealing temperature initially increasing. All the UTFTs with annealing temperature ranging from 250 to 450 °C exhibit good switching properties operating in the enhancement mode with the field-effect mobility of above 8.2 cm2 V−1 s−1. The annealing treatment exhibits extreme importance for the UTFTs to obtain better performance as oxygen vacancy is controlled easily in the ultra-thin films by annealing. The 350 °C-annealed a-ZTO UTFT depicts the largest field-effect mobility of 20.9 cm2 V−1 s−1, the minimum threshold voltage of 2.3 V, the minimum subthreshold swing of 0.339 V/decade, the minimum density of the interfacial trap states of 1.02 × 1012 cm−2 and a large on/off current ratio of 3.3 × 107. Besides, the UTFT with the annealing temperature of 450 °C depicts excellent long-term stability under bias stress due to the least oxygen vacancies. The observations will offer basic design guideline for improvement and future applications of UTFTs.
This work was supported by National Natural Science Foundation of China under Grant no. 51741209 and Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices under Grant no. KFJJ201605.