A visualization of threading dislocations formation and dynamics in mosaic growth of GaN-based light emitting diode epitaxial layers on (0001) sapphire

Ravadgar, P.; Horng, R. H.; Ou, S. L.
December 2012
Applied Physics Letters;12/3/2012, Vol. 101 Issue 23, p231911
Academic Journal
A clear visualization of the origin and characteristics of threading dislocations (TDs) of GaN-based light emitting diode epitaxial layers on (0001) sapphire substrates have been carried out. Special experimental set up and chemical etchant along with field emission scanning electron microscopy are employed to study the dynamics of GaN TDs at different growth stages. Cross-sectional transmission electron microscopy analysis visualized the formation of edge TDs is arising from extension of coalescences at boundaries of different tilting-twining nucleation grains 'mosaic growth.' Etch pits as representatives of edge TDs are in agreement with previous theoretical models and analyses of TDs core position and characteristics.


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