The formation of homo-epitaxially and selectively grown GaN structures within the windows of SiO2 masks were investigated by using transmission electron microscopy and scanning electron microscopy. The structures were produced by means of organometallic vapor-phase epitaxy. A GaN layer under the SiO2 mask provided a crystallographic template for the initial vertical growth of GaN hexagonal pyramids or striped pattern. The SiO2 film provided an amorphous stage upon which lateral growth of GaN could occur, as well as the possible accommodation of mismatch arising from thermal expansion during cooling. Transmission electron microscopic observations revealed a substantial reduction in the dislocation density in areas of lateral growth of GaN which was deposited onto the SiO2 mask. No dislocations were observed in many of these areas.

T.S.Zheleva, O.H.Nam, M.D.Bremser, R.F.Davis: Applied Physics Letters, 1997, 71[17], 2472-4