LATERAL EPITAXIAL OVERGROWTH OF GAN FILMS ON SIO2 AREAS VIA METALORGANIC VAPOR-PHASE EPITAXY

Lateral epitaxial growth and coalescence of GaN regions over SiO2 mask s previously deposited on GaN/AlN/6H-SiC(0001) substrates and containi ng 3 mu m wide rectangular windows spaced 7 mu m apart have been achie ved. The extent and microstructural characteristics of these regions o f lateral overgrowth were a complex function of stripe orientation, gr owth temperature, and triethylgallium (TEG) flow rate. The most succes sful 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 t he underlying GaN/AlN interface, were contained in the GaN grown in th e window regions. The overgrowth regions, by contrast, contained a ver y low density of dislocations. The surfaces of the coalesced layers ha d a terrace structure and an average root mean square roughness of 0.2 6 nm.