Design, Growth and Optimization of 2-micron Indium Gallium Antimonide/Aluminum Gallium Antimonide quantum well based VECSELs on Gallium Arsenide/Aluminum Gallium Arsenide DBRs

The antimonide based vertical external cavity surface emitting lasers (VECSELs) operating in the 1.8 to 2.8 &mgr;m wavelength range are typically based on InGaSb/AlGaSb quantum wells on AlAsSb/GaSb distributed Bragg reflectors (DBRs), grown latticematched on GaSb substrates. In this work the ability to grow such antimonide VECSEL structures on GaAs substrates is explored. The growth of such III-Sb VECSELs on GaAs substrates is non-trivial due to the 7.78% lattice mismatch between the antimonide based active region and the GaAs/AlGaAs DBR. The challenge is therefore to reduce the threading dislocation density in the active region without a very thick metamorphic buffer and this is achieved by inducing 90° interfacial misfit dislocation arrays between the GaSb and GaAs layers. In this work cross section transmission electron microscopy is used to analyze a variety of approaches to designing and growing III-Sb VECSELs on GaAs substrates to achieve a low threading dislocation density. The failure mechanisms in such growths and the extent to which the threading dislocations permeate a thick active region are also analyzed. Finally, growth strategies and techniques to enable low-defect density III-Sb VECSEL active regions on GaAs are discussed.