Strain-compensations for interfacial strain and average strain in InGaAs/InAlP highly compressive-strained multiple quantum well structures on InP grown by gas source molecular beam epitaxy

Abstract

InGaAs/InP or InGaAsP strained layer quantum well (QW) lasers showing enhanced performance over lattice matched lasers have been reported. With a larger compressive or tensile strain, while maintaining a well number, further performance improvements such as low threshold current are anticipated. To fabricate such highly strained multiple quantum well (MQW) structures, it is important both to realize abrupt interfaces and to minimize the average strain of the MQW stacks. We found a molecular beam switching sequence to form the abrupt QW interfaces, and the strain-compensation for both the interfacial strain and the average strain in InGaAs/In(Al)P MQW structures grown by gas source molecular beam epitaxy (GSMBE). This sequence dramatically improved InP/InGaAs heterointerface quality, which was confirmed by an increase in photoluminescence intensity and X-ray diffraction measurement in InGaAs/InP short period superlattice (SPS). Interfacial strain, which is generated by this sequence at every QW top interface, was successfully compensated by employing the different type bond at the QW bottom interfaces. Furthermore, the average strain-compensation was achieved by introducing tensile strain to barrier and the thermal stability for the compensated structure was also confirmed. >