Effect of different valence states point defects on carrier activity and lifetime and photocatalytic properties of GaN:Be/Mg/Ca system

摘要

The effects of Be/Mg/Ca doping on the physical properties of GaN have been widely investigated experimentally and theoretically. However, the effects of Be/Mg/Ca and interstitial H coexistence with different valence states of V-Ga/V-N on the photocatalytic performance of GaN are rarely reported. This study examines the structure and stability of Ga34MHiN36(V-Ga(3-)/V-Ga(2-)/V-Ga(1-)/V-Ga(0)) (M = Be/Mg/Ga) and Ga35MHiN35(V-N(3+)/V-N(1+)/V-N(0)) (M = Be/Mg/Ga) systems and the main factors affecting photocatalytic performance by using the generalized gradient approximation plane wave ultrasoft pseudopotential + U method within the framework of density functional theory. Results show that the Ga34MHiN36(V-Ga(3-)/V-Ga(2-)/V-Ga(1-)/V-Ga(0)) (M = Be/Mg/Ga) and Ga35MHiN35(V-N(3+)/V-N(1+)/V-N(0)) (M = Be/Mg/Ga) systems are more readily formed and have a more stable structure under N-rich conditions compared with other conditions. The visible-light effect, electric dipole moment, effective mass, and oxidation reduction reaction affecting the photocatalytic performance of doped systems are analyzed. The Ga34CaHiN36(V-Ga(3-)) system shows the best visible-light effect, best carrier activity, longest carrier lifetime, and strongest oxidation reduction ability. These results suggest that the Ga34CaHiN36(V-Ga(3-)) system is an excellent photocatalyst that can be utilized in designing novel GaN photocatalysts.