Thin-film transistors based on wide bandgap Ga2O3 films grown by aqueous-solution spin-coating method

Ga2O3 is a wide bandgap oxide semiconductor material with the bandgap value only second in magnitude to diamond among known semiconductors. As a wide-bandgap semiconductor, Ga2O3 has emerged as a new competitor to silicon carbide and III-nitrides in various applications of ultraviolet optoelectronics and high power electronics. However, almost all the devices are based on the Ga2O3 grown by molecular-beam epitaxy or chemical vapour deposition, which is time-consuming and expensive. In this work, the authors report on thin-film transistors based on wide bandgap Ga2O3 films grown by aqueous-solution spin-coating method. The morphological, optical and electrical properties of the films and devices are investigated using a range of characterisation techniques, whilst the effects of post-deposition annealing are also investigated. Both as fabricated and post-annealed Ga2O3 films are found to be very smooth and exhibit wide energy bandgaps of around 4.8 and 4.9 eV, respectively. Thin-film transistors based on the grown Ga2O3 films show n-type conductivity with the maximum electron mobility of 0.1 cm2/Vs.