![]() For emission wavelengths longer than 515 nm, the saturation surprisingly increases again and reaches 95% beyond 560 nm. This broadening of the luminescence decreases the color saturation from 100% to about 70% up a wavelength shorter than 515 nm. The full width at half maximum (FWHM) of the luminescence of visible InGaN quantum well (QW) based emitters increases with wavelength. Despite these defects, the PL is highly improved toward the red wavelengths and compares with the reports on ultrathin AlGaN layers where this has been correlated with the improvement of the crystalline quality, although with less strain compensation. These domains systematically contribute to a local decrease of the QW thickness and most probably to an efficient localization of carriers. It is found that the crystalline quality of the system is progressively degraded when the thickness of the AlGaN interlayer is increased through strain concentrated domains, which randomly form inside the 3 nm GaN low temperature layer. In this instance, AlGaN was grown at the same temperature as the GaN barrier, on top of a protective 3 nm GaN. The compensation is full from an AlGaN layer thickness of 5.2 nm, and this does not change up to the largest one that has been investigated. For different AlGaN strain compensating layer thicknesses varying from 0 to 10.6 nm, a detailed x-ray diffraction analysis shows that the MQW stack becomes completely strained on GaN along a and c. ![]() In this work, InGaN/GaN multi-quantum Wells (MQWs) with strain compensating AlGaN interlayers grown by metalorganic vapor-phase epitaxy have been investigated by high-resolution x-ray diffraction, transmission electron microscopy, and photoluminescence (PL).
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