The photoluminescence of the transparent GaN nanocrystalline solids is studied.T hree new intensive isolated narrow red emission bands (centered at 2.08eV,2.01eV ,1.99eV) and one broad blue band (centered at 2.7eV) are observed.Phonon structu re on the low energy side of the blue band is observed.A mechanism to explain th e origin of these bands is proposed.The three red bands may originate from the t ransitions of deep donor levels to shallow acceptors,while the blue band may fro m the transitions of shallow donors to deep levels with ground and excited state s.The unique property of red emission from the GaN nanocrystalline solids is att ributed to the interaction among the composed nano sized particles which may le d to the generation of high concentration of defects.
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