Bandgap modulation in self-limited two-dimensional Ga2O3 films via defect engineering

We demonstrated the controllable exfoliation of two-dimensional gallium oxide (2D-Ga2O3) thin films via a touch printing process that leverages the self-limiting oxidation behavior of liquid gallium. The resulting films exhibited high thickness uniformity and surface smoothness. After annealing at 800 °C for 1 h, the film thickness was reduced from 6.8 to 3.9 nm due to recrystallization. Furthermore, by precisely modulating the annealing parameters, we introduced point defects and promoted the formation of a Ga–Si–O solid solution, enabling continuous bandgap tunability within the range of 4.88–7.22 eV. This work establishes a clear correlation among annealing, defect evolution, and band structure modulation.