TEM based analysis of III-Sb VECSELs on GaAs substrates for improved laser performance

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

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


The antimonide based vertical external cavity surface emitting lasers (VECSELs) operating in the 1.8 to 2.8 μm 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.

Original languageEnglish (US)
Title of host publicationVertical External Cavity Surface Emitting Lasers (VECSELs) III
StatePublished - 2013
EventVertical External Cavity Surface Emitting Lasers (VECSELs) III - San Francisco, CA, United States
Duration: Feb 3 2013Feb 5 2013

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherVertical External Cavity Surface Emitting Lasers (VECSELs) III
Country/TerritoryUnited States
CitySan Francisco, CA


  • Mismatched epitaxy
  • Quantum well lasers
  • Semiconductor lasers
  • Surface-emitting lasers

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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