Thin‐film transistors based on wide bandgap Ga 2 O 3 films grown by aqueous‐solution spin‐coating method

Ga 2 O 3 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, Ga 2 O 3 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 Ga 2 O 3 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 Ga 2 O 3 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 Ga 2 O 3 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 Ga 2 O 3 films show n‐type conductivity with the maximum electron mobility of 0.1 cm 2 /Vs.