Lateral epitaxial overgrowth of GaN films on SiO2 areas via metalorganic vapor phase epitaxy

Lateral epitaxial growth and coalescence of GaN regions over SiO2 masks previously deposited on GaN/AlN/6H-SiC(0001) substrates and containing 3 mu m wide rectangular windows spaced 7 mu m apart have been achieved. The extent and microstructural characteristics of these regions of lateral overgrowth were a complex function of stripe orientation, growth temperature, and triethylgallium (TEG) flow rate. The most successful growths were obtained from stripes oriented along [<1(1)over bar 00>] at 1100 degrees C and a TEG flow rate of 26 mu mol/min. A density of similar to 10(9) cm(-2) threading dislocations, originating from the underlying GaN/AlN interface, were contained in the GaN grown in the window regions. The overgrowth regions, by contrast, contained a very low density of dislocations. The surfaces of the coalesced layers had a terrace structure and an average root mean square roughness of 0.26 nm.