Photoluminescence study of GaN with dislocations introduced by plastic deformation



We studied photoluminescence characteristics of GaN bulk single crystals with fresh dislocations. GaN crystals prepared from free-standing wafers grown by the HVPE technique were compressed plastically at 900 to 1000 °C. (a/3) [11equation image0]-type dislocations on the (1equation image00) prismatic plane, corresponding to the so-called threading dislocations, were observed in the deformed crystals by TEM. In the PL studies at room temperature and 11 K the near band-edge luminescence becomes weak drastically in the deformed GaN in comparison with that of the as-grown GaN, which seems to imply the introduction of a high density of non-radiative recombination centers into GaN crystals during the plastic deformation. The yellow band luminescence decreased remarkably meanwhile the red band developed relatively in the deformed GaN crystals, which is suggesting that dislocations may not be an origin of the yellow luminescence. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)