Some Optical and Epr Properties of Strain-Free GaN Crystals Obtained by Ammono Method
R. Dwiliński, J.M. Baranowski, M. Kamińska
Institute of Experimental Physics, Warsaw University, Hoża 69, 00-681 Warsaw, Poland

R. Doradziński
Institute of Theoretical Physics, Warsaw University, Hoża 69, 00-681 Warsaw, Poland

J. Garczyński, L. Sierzputowski
Dept. of Chemistry, Warsaw Univ. of Technology, Noakowskiego 4, 00-661 Warsaw, Poland

and M. Palczewska
Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw, Poland
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AMMONO GaN is grown spontaneously from ammonia solution in form of regular, well shaped, few micrometer crystals. Photoluminescence spectra of these crystals are characterized by fixed positions of very narrow exciton lines (FWHM down to 1 meV), where free excitons A, B, C, resolved two donor bound excitons and acceptor bound exciton are visible. Fixed position of exciton lines is in contrast to small changes of line energies which have been always observed for epitaxial GaN layers because of strain present in them. Free electron concentration of AMMONO GaN is less than few times 1015 cm-3, as estimated from EPR signal of shallow donor. The above-mentioned facts qualified these crystals as state of the art strain-free, model material for basic parameter measurements of GaN. In this work, results of PL and EPR measurements performed on AMMONO GaN crystals are presented and discussed.
DOI: 10.12693/APhysPolA.92.737
PACS numbers: 81.10.Dn