Transfer and recombination mechanism of carriers in phase-separated InGaN quantum wells

Photoluminescence (PL) properties of InGaN/GaN multiple quantum wells are studied. Two InGaN-related peaks are observed in the full PL spectrum and are assigned to the quasi-quantum dots (QDs) (2.42 eV) and the InGaN matrix (2.66 eV), due to a strong phase separation. As the carriers transfer from the matrix down to the QDs, an increase of the QDs-related PL intensity (ID) accompanied by the decrease of the matrix-related PL intensity (IM) results. A slight increase of the total PL intensity is also observed, and is attributed to the QDs providing deep potential levels to suppress the outflow of carriers toward surrounding nonradiative centers. A piezoelectric field resulting from the high indium content inside the QDs is observed, which is speculated from Coulomb screening effect. Additionally, we find that the sublinear dependence of the ID on excitation power (P) is due to the saturation of the QDs states, while the superlinear dependence of the IM on P is simultaneously attributed to the suppression o...

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