Near-field investigation of spatial variations of (20(2)over-bar(1)over-bar) InGaN quantum well emission spectra

Scanning near-field optical spectroscopy was applied to semipolar (20 (2) over bar(1) over bar) InGaN/GaN quantum wells (QWs) to evaluate spatial homogeneity of QW band gap and its dependence on the growth conditions. In the most uniform QW, photoluminescence (PL) spectra were found to be narrow with small peak wavelength and spectral width variations. A QW grown at reduced temperature showed sub-micrometer size PL features aligned along the a axis and caused by nonuniform In incorporation at surface undulations. At extended defects, complex and strongly varying near-field spectra were observed and tentatively assigned to QW segments of different orientations around these defects. (C) 2013 AIP Publishing LLC.