High-performance ZnO thin-film transistors with location-controlled crystal grains fabricated by low-temperature hydrothermal method

In this paper, high-performance bottom-gate (BG) thin-?lm transistors (TFTs) with zinc oxide (ZnO) arti?cially location-controlled lateral grain growth have been prepared via low-temperature hydrothermal method. For the proper design of source/drain structure of ZnO/Ti/Pt thin ?lms, the grains can be laterally grown from the under-cut ZnO beneath the Ti/Pt layer. Consequently, the single one vertical grain boundary perpendicular to the current ?ow will be produced in the channel region as the grown grains from the source/drain both sides are impinged. As compared with the conventional sputtered ZnO BG-TFTs, the proposed location-controlled hydrothermal ZnO BG-TFTs (W/L = 250 μm/10 μm) demonstrated the higher ?eld-effect mobility of 6.09 cm ²/V ̇ s, lower threshold voltage of 3.67 V, higher on/off current ratio above 10 ⁶, and superior current drivability, re?ecting the high-quality ZnO thin ?lms with less grain boundary effect in the channel region.