Effects of substrate temperature on performance of calcium-doped zinc oxide TFTs

Abstract

In this reported work, high-performance fully transparent bottom-gate-type calcium-doped zinc oxide thin-film transistors (Ca-ZnO TFTs) have been successfully fabricated on glass substrate. The effects of substrate temperature during active layer deposition on the electrical properties of Ca-ZnO TFTs were investigated and an optimum condition (substrate temperature: 100°C) was achieved. The optimised thin-film transistors (TFTs) exhibit excellent electrical properties, with an off-state current (Ioff) of 1.31 × 10-12 A, an Ion/Ioff current ratio of 3.015 × 108, a saturation mobility (μsat) of 25 cm2 /Vs and a threshold voltage (Vt) of 4.24 V. The variation trend of Vt, the Ion/Ioff current ratio and μsat against substrate temperatures is analysed in detail. The experimental results suggest that the performance of Ca- ZnO TFTs can be improved effectively by optimum substrate temperature.