Defect-related photoluminescence and photoluminescence excitation as a method to study the excitonic bandgap of AlN epitaxial layers: Experimental and ab initio analysis

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Abstract

We report defect-related photoluminescence (PL) and its vacuum ultraviolet photoluminescence excitation (PLE) spectra of aluminum nitride layers with various layer thicknesses and dislocation densities grown on two different substrates: sapphire and silicon. The defect-related transitions have been distinguished and examined in the emission and excitation spectra investigated under synchrotron radiation. The broad PL bands of two defect levels in the AlN were detected at around 3 eV and 4 eV. In the PLE spectra of these bands, a sharp excitonic peak originating most probably from the A-exciton of AlN was clearly visible. Taking into account the exciton binding energy, the measurements allow determination of the bandgaps of the investigated AlN samples and their temperature dependencies. Next, they are compared with the literature data obtained by other experimental techniques for bulk AlN crystals and layers grown on different substrates. The obtained results revealed that the AlN bandgap depends on the substrate. The theoretical analysis using density functional theory calculations showed that the effect is induced by the tetragonal strain related to the lattice mismatch between the substrate and the AlN layer, which has a strong influence on the spectral positions of the intrinsic excitons, and consequently on the bandgap of AlN layers.

Detaljer

Författare
  • Agata Kaminska
  • Kamil Koronski
  • Pawel Strak
  • Aleksandra Wierzbicka
  • Marta Sobanska
  • Kamil Klosek
  • Dmitrii V. Nechaev
  • Vladimir Pankratov
  • Kirill Chernenko
  • Stanislaw Krukowski
  • Zbigniew R. Zytkiewicz
Enheter & grupper
Externa organisationer
  • Cardinal Stefan Wyszyński University in Warsaw
  • High Pressure Research Center of the Polish Academy of Sciences (UNIPRESS)
  • Ioffe Physical-Technical Institute of the Russian Academy of Sciences
  • Laboratory of Hybrid Nanostructured Materials, NUST MISiS
  • Institute of Physics PAS
  • University of Latvia
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Den kondenserade materiens fysik
Originalspråkengelska
Artikelnummer232101
TidskriftApplied Physics Letters
Volym117
Utgåva nummer23
StatusPublished - 2020
PublikationskategoriForskning
Peer review utfördJa