Epitaxial lateral overgrowth of GaN on Si (111)

Completely coalesced epitaxial lateral overgrowth (ELO) of GaN on silicon (111) is presented for ELO layer thicknesses below 3 mum. Fast lateral expansion of the ELO-GaN was achieved by metalorganic vapor phase epitaxy at high growth temperature (1120 degreesC), low pressure (100 mbar), and a high V/III ratio of 8000. Thus full coalescence and a smooth surface (roughness of 5 nm across 100 mum(2)) are accomplished for wide SixNy masks along [1 (1) over bar 00](GaN) with a 10 mum period and 3 mum openings. Atomic force microscopy and transmission electron microscopy are used to assess the quality of the layers. The density of dislocations is reduced from 8x10(9) cm(-2) in the GaN template down to 8x10(8) cm(-2) above the mask openings, and finally to 5x10(7) cm(-2) in the laterally overgrown regions. The corresponding strong improvement of the optical properties and the stress present within the epilayer are evidenced by scanning cathodoluminescence microscopy. (C) 2003 American Institute of Physics.