Nanoheteroepitaxy of GaN on a nanopore array of Si(111) surface

Nanoheteroepitaxial (NHE) growth of GaN using AlN/AlGaN as a graded buffer layer by metalorganic chemical vapor deposition has been demonstrated on the nanoporous patterned Si(111) substrates. The nanopore array on Si(111) has been fabricated by using anodized aluminum oxide membrane as an induced couple plasma dry etching mask. The reduction of the threading dislocation density and relaxation of the tensile stress in NHE GaN are revealed by transmission electron microscopy (TEM), micro-Raman spectrum and photoluminescence spectrum, respectively. Cross-sectional TEM analysis shows that dislocations nucleated at the interface are forced to bend into (0001) basal plane. Red shift in the E2 (TO) phonon peak of micro-Raman spectrum indicates the relaxation of tensile stress in the nanoheteroepitaxial lateral overgrowth of GaN. A single step ELO without mask on nanopatterned Si(111) substrates is a simple and promising way for the improvement of the quality of GaN on Si substrates.