Tuning the electronic structure of quasi-two-dimensional β-Ga2O3 by vacancy and doping

First principles calculations have been adopted to study the electronic properties of QTD β-Ga2O3 modulated by vacancy and doping. The calculated results indicate the band gaps of QTD β-Ga2O3 are not largely decreased (∼0.36 eV) compared with its bulk form. By introducing Ga and O vacancies, the p-type and n-type QTD β-Ga2O3 can be obtained, respectively. The band gap of the system with O vacancy decrease to 0.7 eV due to the occurrence of the band gap states. All the substitutional dopants induce the system act as n-type doping. Cr, Fe, N and Si atoms create flat band states in the vicinity of the Fermi level, which decrease the band gap of the system. More promising n-type doping can be achieved by placing metal atoms on the surface of QTD β-Ga2O3. The decreased band gap of Sn adsorption can efficiently expand the range of the liner optical absorption of QTD β-Ga2O3.