Free carrier screening of quantum-confined stark effect affecting on luminescence energy shift and carrier lifetime in InGaN quantum wells

We have studied the carrier density dependence of carrier lifetime and luminescence energy in InGaN multiple quantum wells (MQW) mainly in relation with free carrier screening of quantum-confined Stark effect (QCSE). We have performed a systematic time-resolved photoluminescence (PL) measurement of MQW for various carrier densities with three different well widths (2.5 nm, 4.0 nm, 5.5 nm). For low carrier density, with decreasing carrier density, carrier recombination rate and Pl, energy are found to decrease nonlinearly. These decreases are larger for wider well width. For high carrier densities, the carrier recombination rate becomes constant and the PL energy shifts linearly. We show that the energy shift for 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 in accordance with the calculated band-filling effect.