Improving photoelectric characteristics of GaN-based green laser diodes by inserting electron blocking layer with gradient Al composition

This paper proposes four new gradient composition electron blocking layer (EBL) structures to enhance the photoelectric performance of GaN-based green laser diodes (LDs). The optical and electrical properties of new structure LDs are theoretically analyzed by LASTIP. It is observed that the implementation of a gradient composition EBL structure increases the effective barrier height for electrons, thereby better inhibiting the electron current overflow from the active region. In addition, the optical field leakage is effectively suppressed, lower threshold current and higher output power are obtained. The four different new structures have obvious differences in the improvement of the hole current injection and slope efficiency of multiple quantum well (MQW) LDs, and the underlying reasons for these phenomena are explored. Simulation results indicate that adopting a gradually descending Al component EBL structure yields optimal improvements in the photoelectric performance of LDs. • Four new structures of LD were designed and their electrical and optical properties structures were compared with that of traditional LD structures. • The conduction and valance band structure of new LD structures are analyzed. • The reasons for differences of photoelectric characteristics between four new structures are investigated in details.