Indium oxide (In2O3) has been reported widely due to its good optical properties and stability in optoelectronics and other fields. However, it is difficult to realize thickness control of atomically thin In2O3, which will confine the use of In2O3 films. Here, we report a simple and precise method to synthesize thickness-controllable In2O3 films using printed oxide skin of liquid metals. The cleaning processes were investigated to remove the metal residues on the films. It was found that liquid metal washing and annealing procedures could remove the residues without damaging the films and thus improve the uniformity. At the same time, the thickness of In2O3 films was controlled by adjusting the oxygen concentration of the atmosphere. Furthermore, the band gap regulation of indium oxide was realized by adjusting the thickness, which provided a good basis for the selenization of oxide films.

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