Type-II GaAsBi QDs/GaSb for middle-wave and long-wave infrared lasers

A GaSb/GaAsBi type-II quantum dot structure is proposed for fabricating middle-wave infrared (MWIR) and long-wave infrared (LWIR) lasers. The finite element method is employed to investigate the train distributions and band structures of the proposed structures with different Bi contents and QD sizes. It is found that the strain component ε_xx decreases with Bi contents and heights, and increases with the diameter, while the component ε_zz inversely changes. The charge carriers recombine between the electrons in GaAsBi QDs and the holes in GaSb. The energy of the ground states of electrons of GaAsBi QDs decreases and the emission wavelength increases with the Bi contents and QD sizes. The emission wavelength can cover MWIR and LWIR ranges with proper Bi contents and QD sizes. The proposed structure provides a feasible way to fabricate MWIR and LWIR lasers.