Two-Electron Transition in Homoepitaxial GaN Layers
A. Fiorek, J.M. Baranowski, A. Wysmołek, K. Pakuła, M. Wojdak
Institute of Experimental Physics, Warsaw University, Hoża 69, 00-681 Warsaw, Poland

I. Grzegory and S. Porowski
High Pressure Research Center, Polish Academy of Sciences, Sokołowska 29, 01-142 Warsaw, Poland
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It is shown that the luminescence mapping is a powerful method to help identify optical transitions. Two-electron transition was identified in the homoepitaxial GaN layer by this technique. It was found that the donor and acceptor bound exciton emissions are spatially displaced and show intensity maxima at different places of the epitaxial layer. It was also found that the 3.45 eV line, suspected as "two-electron transition", follows exactly the donor bound exciton spatial distribution. Donor bound exciton recombines leaving the neutral donor in the excited 2s state. Thus, 1s-2s excitation being equal to 22 meV corresponds to 29 meV hydrogenic donor binding energy. This is the first identification of the two-electron transition in GaN.
DOI: 10.12693/APhysPolA.92.742
PACS numbers: 78.66.Fd, 78.55.Cr