A density functional theory study of electronic properties of Ce:GaN

First principle calculations for Ce:GaN using mBJ, GGA, LDA (+U) are presented to demonstrate the electronic, optical and magnetic properties of the system. The effect of variation of U on Ce 4f levels and forbidden gap are discussed in detail and an optimized value of Ueff (5.3 eV) is obtained. The 4f levels were observed shifted away from Fermi level with increase in value of Ueff. Our results revealed that dopant introduces localized level near conduction band whose width increases with increase in doping concentration. It is noted that for large Ce concentration, the impurity band is found merged with bottom of the conduction band and form a new conduction band edge. It predicts the band gap narrowing in the material which is expected to facilitate the optical transitions.