26 February 2013 TEM based analysis of III-Sb VECSELs on GaAs substrates for improved laser performance
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Proceedings Volume 8606, Vertical External Cavity Surface Emitting Lasers (VECSELs) III; 86060E (2013); doi: 10.1117/12.2005301
Event: SPIE LASE, 2013, San Francisco, California, United States
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, D. Shima, T. J. Rotter, S. P. R . Clark, S. J. Addamane, C. P. Hains, L. R. Dawson, G. Balakrishnan, R. Bedford, Y. Y. Lai, A. Laurain, J. Hader, 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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KEYWORDS
Gallium arsenide

Gallium antimonide

Quantum wells

Interfaces

Transmission electron microscopy

Phonons

Neodymium

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