Room-temperature fabrication of high-performance H doped ZnO thin-film transistors

Highlights: • ZnO:H-TFTs were fabricated in Ar + H₂ sputtering atmosphere at room temperature. • The TFT performance can be significantly improved by appropriate amount of H doping. • Hydrogen could act as a defect passivator and a shallow donor in ZnO thin films. • H doping increases the carrier concentration and reduces the interface trap density. • High-performance TFTs achieved at room temperature are good for flexible electronics. We prepared ZnO:H thin films in Ar + H₂ atmosphere with substrate at room temperature by magnetron sputtering, the effect of H₂ flow ratio on the properties of thin films and the performance of ZnO:H thin-film transistors (ZnO:H-TFTs) were investigated. Hydrogen could act as a defect passivator and a shallow donor in ZnO films, which not only increases the carrier concentration but also reduces the interface trap density, therefore improving the TFT performance. Compared with pristine ZnO-TFT, the optimal ZnO:H-TFT exhibits great enhancement, with the saturation mobility increasing from 2.17 cm²/V⋅s to 5.17 cm²/V⋅s, the on/off ratio increasing from 3.47 × 10⁵ to 4.98 × 10⁶, the threshold voltage reducing from 15.12 V to 6.03 V. Meanwhile, the positive and negative bias stability is also improved from ΔV_th = 3.89 V and −6.35 V to 1.74 V and −3.72 V, respectively. Our results show that introducing hydrogen into the sputtering atmosphere to achieve hydrogen doping is a simple and effective method to improve the performance of ZnO-TFTs. Furthermore, the high-performance ZnO:H-TFTs fabricated at room temperature have great potential in the field of flexible electronics.