High spatial uniformity of photoluminescence spectra in semipolar (2021) plane InGaN/GaN quantum wells.

Scanning near-field optical spectroscopy was applied to study spatial variations of emission spectra at room temperature in semipolar (2021) In_xGa_1-xN/GaN single quantum wells (QWs) for 0.11 ⩽ x ⩽ 0:36. Photoluminescence (PL) was found to be highly uniform, with peak wavelength deviations and peak intensity deviations divided by average values in the range of 6-12 meV and 0.03-0.07, respectively. Near-field maps of PL parameters showed large, ~5 to 10μm size areas of similar values, as opposed to 100 nm scale variations, often reported for InGaN QWs. The nearfield PL spectra were found to broaden with increasing InN molar fraction. In the low In content QWs, the broadening is primarily determined by the random cation distribution, while for larger InN molar fractions 10 nm scale localization sites with increasingly deeper band potentials are suggested as the linewidth broadening cause. [ABSTRACT FROM AUTHOR]