Epitaxial lateral overgrowth (ELO) has been used to reduce threading dislocation (TD) densities in GaN. This paper reports transmission and scanning electron microscopy studies of TDs in GaN films grown by ELO on GaN nanocolumns produced either during growth by MBE (method 1), or by self-organised patterning on a uniform layer grown by MOCVD (method 2). In method 1, isolated nanocolumns grew without TDs, but some TDs formed when nanocolumns coalesced. Although some of these TDs extended through the overlayer, extensive lateral migration of others, depending on the dislocation type, led to dislocation annihilation, lowering the overall TD density. In method 2, a similar process of lateral migration of TDs was observed during ELO, resulting in a continuous GaN overlayer with TD densities less than 108 cm-2.
|Number of pages||3|
|Journal||Physica Status Solidi (C) Current Topics in Solid State Physics|
|Early online date||17 Apr 2008|
|Publication status||Published - May 2008|
|Event||7th International Conference of Nitride Semiconductors, ICNS-7, September 16, 2007 - September 21, 2007 - Las Vegas, NV, USA United States|
Duration: 1 May 2008 → …