title: First principles study of bismuth alloying effects in GaAs saturable absorber.
abstract: First principles hybrid functional calculations have been carried out to study electronic properties of GaAs with Bi alloying effects. It is found that the doping of Bi into GaAs reduces the bandgap due to the intraband level repulsions between Bi induced states and host states, and the Bi-related impurity states originate from the hybridization of Bi-6p and its nearest As-4p orbitals. With the increase of Bi concentration in GaAs, the bandgap decreases monotonously. The calculated optical properties of the undoped and Bi-doped GaAs are similar except the shift toward lower energy of absorption edge and main absorption peaks with Bi doping. These results suggest a promising application of GaBi(x)As(1-x) alloy as semiconductor saturable absorber in Q-switched or mode-locked laser.
authors.affiliation: School of Information Science and Engineering, Shandong University, Jinan, China. dechun@sdu.edu.cn
authors.forename: Dechun
authors.initials: D
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.forename: Shengzhi
authors.initials: S
authors.lastname: Zhao
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Cai
authors.forename: Yuanping
authors.initials: Y
authors.lastname: Feng
mesh_terms: D000042:Absorption; D000465:Algorithms; D001152:Arsenicals / Q000737:chemistry*; D001729:Bismuth / Q000737:chemistry*; D004867:Equipment Design; D005708:Gallium / Q000737:chemistry*; D007834:Lasers; D054023:Lasers, Semiconductor; D008027:Light; D008968:Molecular Conformation; D055095:Optics and Photonics
chemical_list: D001152:Arsenicals; C043055:gallium arsenide; D005708:Gallium; D001729:Bismuth