Strain-compensated InGaAs/GaAsP/GaInAsP/GaInP quantum well lasers (λ∼0.98 μm) grown by gas-source molecular beam epitaxy

Abstract

We report on the first strain-compensated InGaAs/GaAsP/GaInAsP/GaInP separate-confinement-heterostructure quantum well lasers emitting at about 0.98 μm. The laser structure was grown by gas-source molecular beam epitaxy. The lasers exhibited low threshold current densities and high characteristic temperatures. It was found that the structural and optical quality of a strain-compensated InGaAs/GaAsP multiple-quantum well (MQW) was superior to that of an InGaAs/GaAs MQW when the number of quantum wells was large. This was due to the presence of tensile strain in GaAsP which balanced compressive strain in InGaAs so that the InGaAs lattice does not relax. As a result, much fewer defects were formed in InGaAs/GaAsP than in InGaAs/GaAs. Thus strain-compensated InGaAs/GaAsP MQW structures are desirable for device applications which require many quantum wells.