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The influence of inhomogeneities and defects on novel quantum well and quantum dot based infrared-emitting semiconductor lasers

In this paper we discuss the development of new semiconductor materials and approaches to overcome the fundamental limitations of well established (Al, In)GaAs/InP and InGaAsP/InP infrared-emitting lasers. We consider three approaches; dilute nitride InGaAsN-based structures; InAs-based quantum dot/dash structures and the most recently emerging dilute bismide (GaAsBi, InGaAsBi), all of which may be grown on either GaAs or InP substrates. These material systems provide a range of possibilities for band engineering and strain control, thereby giving new routes to improve device efficiency, overcoming existing limitations of device performance and to develop range of new cost-efficient devices with improved characteristics. However, all of these approaches have common difficulties related to establishing optimised growth conditions to produce high quality material for device fabrication. Particularly, in this paper we compare and contrast the effects of inhomogeneous carrier distribution in these systems and discuss the influence of this on the physical properties of lasers developed using these approaches.