0.98-μm InGaAs-InGaP strained quantum-well lasers with GaAs-InGaP superlattice optical confinement layer

We have proposed a GaAs-InGaP superlattice optical confinement layer (SL-OCL), which replaces graded InGaAsP alloy layers in 0.98-μm InGaAs-InGaP graded-index separate-confinement-heterostructure (GRINSCH) strained quantum-well (QW) lasers. Theoretical study of the multiquantum barrier (MQB) effect of the GaAs-InGaP SL indicates that electrons in the GaAs OCL feel more than two times higher barrier height than the classical bulk barrier height. Actually, the increase of internal quantum efficiency and the decrease of threshold current density were confirmed. Furthermore, the extremely high characteristic temperature T₀ of 300 K around RT was obtained. These improvements of laser characteristics, especially high T₀, is mainly owing to the enhancement of the carrier confinement due to the MQB effect of the SL-OCL.