High quality GaN epitaxial growth on [formula omitted]-Ga2O3 substrate enabled by self-assembled SiO2 nanospheres

Abstract

To obtain high-quality GaN epitaxial film on (−2 0 1) β-Ga2O3 substrate, periodic SiO2 nanosphere monolayer was self-assembled followed by inductively coupled plasma (ICP) etching. This periodic SiO2 nanosphere patterned Ga2O3 substrate (SiO2-NPGS) enables nanoscale epitaxial lateral overgrowth (NELOG) of GaN film. Compared to planar Ga2O3 substrate, SiO2-NPGS shows great potential for epitaxial GaN with (0 0 0 2) and (1 0 −1 2) full-width at half-maximum (FWHM) reduced from 555 to 388 arcsec, and 634 to 356 arcsec, respectively. Raman spectra also confirm that the as-grown GaN film on SiO2-NPGS is almost stress-free. The dislocation reduction is also observed by cross-sectional transmission electron microscope (TEM). The embedded SiO2-nanosphere blocks the dislocations and induces the GaN lateral overgrowth, thus leading to the significant reduction of the threading dislocation densities. These findings provide a new way for high quality stress-free GaN film epitaxial growth on Ga2O3 substrate.