Improvement in the optical quality of GaInNAs/GaInAs quantum well structures by interfacial strain reduction

The authors report on the use of thin (2 nm) layers with intermediate strain placed between the barriers and the quantum wells of GaInNAs/GaInNAs structures in order to reduce the effect of strain on the quantum wells. A comparison between samples with and without these strain-mediating layers has been performed using various optical and structural techniques, such as photoluminescence, high-resolution X-ray diffractometry and transmission electron microscopy. The results show that the introduction of strain-mediating layers brings beneficial effects to the structural quality of the active region which, in turn, is reflected by a two orders of magnitude improvement in the photoluminescence intensity. It is thought that this structural design approach can be successfully used to obtain high performance 1.3 and 1.55 μm lasers based on dilute nitride materials grown on GaAs.