The photoluminescence characteristics of bulk single crystals with fresh dislocations were studied. Crystals prepared from free-standing wafers, grown by using the HVPE technique, were compressed plastically at 900 to 1000C. Subsequently, (a/3)[11▪0]-type dislocations on the (1¯1▪0) prismatic plane - corresponding to so-called threading dislocations - were observed in the deformed crystals by using transmission electron microscopy. In photoluminescence studies performed at room temperature and 11K, the near-band-edge luminescence became markedly weak in deformed GaN; in comparison with as-grown GaN. This seemed to imply the introduction of a high density of non-radiative recombination centers into the crystals during plastic deformation. The yellow-band luminescence decreased markedly, while the red band developed in the deformed crystals; suggesting that dislocations might not be the origin of the yellow luminescence.

Photoluminescence Study of GaN with Dislocations Introduced by Plastic Deformation. I.Yonenaga, H.Makino, S.Itoh, T.Yao: Physica Status Solidi C, 2005, 2[6], 1817-21