Carrier modulation and effective passivation of tin oxide thin-film transistors by organic surface doping

Doping is a useful technique for metal oxide thin-film transistors (TFTs) to adjust the threshold voltage and charge carrier density. However, a notable drawback is the disruption of the microstructure caused by doping crystalline lattice, leading to a partial decrease in charge carrier mobility. In this work, we suggest a surface doping technique that modifies the carrier concentration and passivates the device surface while preserving the channel layer lattice structure through the use of organic dopant molecules. It is shown that tin oxide (SnO₂) TFTs doped in this manner typically exhibit improved electrical characteristics, particularly greater mobility and a noticeably lower threshold voltage, without negatively affecting the devices on/off current ratio. Furthermore, compared to pristine devices, bias stress stability and long-term durability are also enhanced. These findings suggest that surface doping may find use in high-performance oxide semiconductor devices and circuits.