Coupling of LO Phonons to Excitons in GaN
A. Wysmołek, P. Łomiak, J.M. Baranowski, K. Pakuła, R. Stępniewski, K.P. Korona
Institute of Experimental Physics, Warsaw University, Hoża 69, 00-681 Warszawa, Poland

I. Grzegory, M. Boćkowski and S. Porowski
High Pressure Research Center, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warszawa, Poland
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The photoluminescence of homoepitaxial and heteroepitaxial GaN layers is reported. It is shown that the coupling between LO phonons and neutral acceptor bound excitons is much stronger than the coupling between LO phonons and neutral donor bound excitons. In undoped homoepitaxial layer, in spite of that the no-phonon emission due to donor bound excitons is one order of magnitude stronger than the acceptor bound excitons emission, the predominant structure in the LO phonon replica of the excitonic spectrum is related to optical transitions involving acceptor bound excitons. Temperature studies showed that at higher temperature the LO phonon replica is related to free excitons.
DOI: 10.12693/APhysPolA.90.981
PACS numbers: 78.55.Cr, 63.20.Mt, 71.55.Eq