A two-step method for epitaxial lateral overgrowth of GaN

We report on a two-step process for the epitaxial lateral overgrowth of GaN . In the first step, the selective area epitaxy proceeds at low temperature and GaN stripes with a triangular cross section are rapidly obtained. Then , in a second step, these stripes are used as seeds for epitaxial lateral o vergrowth, the growth conditions being changed either by increasing the gro wth temperature or by introducing a Mg precursor. Fully coalesced and plana r GaN samples are: thereby achieved. A comparison between samples grown wit hout and with this two-step process evidences an additional reduction in th e threading defects density with the two-step process. The dislocations eme rging from the seeds are drastically reduced to 5 x 10(6) to 10(7) cm(-2) b etween the coalescence boundaries.