Improved characteristics and issues of m-plane InGaN films grown on low defect density m-plane freestanding GaN substrates by metalorganic vapor phase epitaxy

Improved quantum efficiency and short radiative lifetime were demonstrated for the near-band-edge emission of nearly stacking-fault-free, 200–250-nm-thick, m-plane pseudomorphic In_xGa_1-xN (0≪x≤0.14) films grown by metalorganic vapor phase epitaxy on the low threading dislocation density (≪5×10⁶ cm^-2) freestanding (FS) GaN substrates. Values of full width at half maximum of x-ray ω-rocking curves of the In_xGa_1-xN films remain unchanged as the substrate values being 80 and 60 arcsec for the (1010) diffraction with <0001> and <1120> azimuths, respectively, and 80 arcsec for the (1012) diffraction. As the surface flatness was improved, the incorporation efficiency of In was lower than the cases for c-plane growth and m-plane growth on a defective GaN substrate, according to nonidentical surface kinetics and absence of inclined/tilted planes, respectively.