Growth of GaN films on circle array patterned Si (111) substrates
GaN growth on patterned Si by a two-step process results in coalescence and a mirror-like surface.
GaN film with very low defect density was obtained.
GaN film grown on the periodically patterned Si substrate is relaxed as revealed by PL results.
Low stress, low defect density GaN was successfully grown on circle array patterned Si (111) substrate using AlN as the buffer followed by two steps growth of the GaN film. Raman measurement shows a reduction of in plane biaxial stress for the GaN film grown on patterned substrate. The slight blueshift of PL peaks further provides evidence that the tensile stress in the GaN film was relaxed. It is believed that the grain boundaries of the polycrystalline AlN buffer layer and the dislocations in the GaN film grown helped to relieve the stress induced by the lattice and the thermal coefficient mismatches during growth.