ACTA

Photoluminescence Dynamics of GaN/Si Nanowires

K.P. Korona^a, Z.R. Zytkiewicz^b, P. Perkowska^a, J. Borysiuk^{a, b}, J. Binder^a, M. Sobanska^b and K. Klosek^b
^aInstitute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, 00-681 Warsaw, Poland
^bInstitute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw, Poland

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In this work we present analysis of carriers dynamics in samples of GaN nanowires grown on silicon. The samples exhibit bright luminescence of bulk donor-bound excitons at 3.472 eV, surface defect-bound excitons at 3.450 eV (SDX) and a broad (0.05 eV) band centered at 3.47 eV caused probably by single free exciton and bi-exciton recombination. The SDX emission has long lifetime τ = 0.6 ns at 4 K and can be observed up to 50 K. At higher temperatures luminescence is dominated by free excitons. The broad excitonic band is best visible under high excitation, and reveals fast, non-exponential dynamics. We present mathematical model assuming exciton-exciton interaction leading to the Auger processes. The model includes n² (Langevin) term and describes well the non-exponential dynamics of the excitonic band.

DOI: 10.12693/APhysPolA.122.1001
PACS numbers: 78.55.Cr, 73.22.-f, 78.47.jd