Al1-xInxN/GaN bilayers: structure, morphology and optical properties


Al1-xInxN/GaN bilayers: structure, morphology and optical properties

Lorenz, K.; Magalhães, S.; Franco, N.; Darakchieva, V.; Barradas, N. P.; Alves, E.; Pereira, S.; Correia, M. R.; Munnik, F.; Martin, R. W.; O’Donnell, K. P.; Watson, I. M.

High quality Al1-xInxN/GaN bilayers, grown by Metal Organic Chemical Vapour Deposition (MOCVD), were characterized using structural and optical techniques. Compositional analysis was performed using Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection Analysis (ERDA). The InN molar fraction x decreased approximately linearly with increasing growth temperature and ranged from x=0.13 to 0.24. Up to x=0.20 the layers grow pseudomorphically to GaN with good crystalline quality. These layers show a smooth surface with V-shaped pits. Two layers with InN contents around 24% showed partial strain relaxation. However, the mechanisms leading to relaxation of compressive strain are very different in the two samples grown both at low temperature but with different growth rate. One sample shows a decreased c/a ratio, as expected for relaxation of the compressive strain, while In was shown to be homogeneously distributed with depth. Another sample started to grow with x=0.24 but relaxed mainly by reduction of the incorporated InN content towards the lattice-match composition of x~0.17. Both samples have an increased surface roughness. All samples show strong Al1-xInxN band edge luminescence with large bowing parameter and Stokes’ shifts.

  • Invited lecture (Conferences)
    International conference on Nitride Semiconductors, ICNS-8, 18.-23.10.2009, JeJu, South Korea
  • Physica Status Solidi (B) 247(2010)7, 1740-1746
    DOI: 10.1002/pssb.200983656
    ISSN: 0370-1972
    Cited 11 times in Scopus

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Publ.-Id: 12932