Greatly improved carrier injection in GaN-based VCSEL by multiple quantum barrier electron blocking layer

In this report, the fabrication and characteristics of III-nitride based vertical-cavity surface-emitting laser (VCSEL) with bulk AlGaN and AlGaN/GaN superlattice electron blocking layer (EBL) are observed experimentally and theoretically. The results have been revealed that laser performance is improved by using superlattice EBL. The output power and the slope efficiency are enhanced by the improvement of carrier injection into active region. And the reduction of threshold current density from 10 to 8 kA/cm2 is also observed. Theoretical calculation results suggest that the improved carrier injection efficiency can be mainly attributed to the partial release of the strain at the interface of last quantum barrier and superlattice EBL and hence the increase of electrons and holes effective barrier height.