To clarify the carrier density dependence of carrier lifetime and luminescence energy, we have performed a systematic study of time-resolved photoluminescence (PL) measurements of In0.12Ga0.88N/In0.03Ga0.97N multiple quantum wells for various carrier density. The carrier recombination rate and the PL energy, for the carrier density below 1.5× 1018cm-3, are found to decrease nonlinearly with the decrease of the carrier density, although the carrier lifetime is constant and the PL energy shifts linearly for carrier density above this value. We show that the energy shift for the small carrier density and the change in the carrier lifetime are well explained by the free carrier screening effect which compensates the internal electric field. The linear energy shift for the high carrier density is attributed to the band-filling effect.
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