26 February 2013 TEM based analysis of III-Sb VECSELs on GaAs substrates for improved laser performance
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Abstract
The antimonide based vertical external cavity surface emitting lasers (VECSELs) operating in the 1.8 to 2.8 Tm wavelength range are typically based on InGaAsSb/AlGaAsSb quantum wells on AlAsSb/GaSb distributed Bragg reflectors (DBRs) grown lattice-matched on GaSb substrates. The ability to grow such antimonide VECSEL structures on GaAs substrates can take advantage of the superior AlAs based etch-stop layers and mature DBR technology based on GaAs substrates. 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 mist dislocation arrays between the GaSb and GaAs layers. In this presentation we make use of cross section transmission electron microscopy to analyze a variety of approaches to designing and growing III-Sb VECSELs on GaAs substrates to achieve a low threading dislocation density. We shall demonstrate the failure mechanisms in such growths and we analyze the extent to which the threading dislocations are able to permeate a thick active region. Finally, we present growth strategies and supporting results showing low-defect density III-Sb VECSEL active regions on GaAs.
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P. Ahirwar, P. Ahirwar, D. Shima, D. Shima, T. J. Rotter, T. J. Rotter, S. P. R . Clark, S. P. R . Clark, S. J. Addamane, S. J. Addamane, C. P. Hains, C. P. Hains, L. R. Dawson, L. R. Dawson, G. Balakrishnan, G. Balakrishnan, R. Bedford, R. Bedford, Y. Y. Lai, Y. Y. Lai, A. Laurain, A. Laurain, J. Hader, J. Hader, J. V. Moloney, J. V. Moloney, "TEM based analysis of III-Sb VECSELs on GaAs substrates for improved laser performance", Proc. SPIE 8606, Vertical External Cavity Surface Emitting Lasers (VECSELs) III, 86060E (26 February 2013); doi: 10.1117/12.2005301; https://doi.org/10.1117/12.2005301
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