Photoluminescence study of Si-doped GaN∕Al0.07Ga0.93N multiple quantum wells with different dopant position

The effects of Si doping on the emission energy and recombination dynamics in a set of GaN∕Al0.07Ga0.93N multiple quantum well (MQW) samples with different position of the dopant layer were studied by means of photoluminescence (PL) and time-resolved PL measurements. When the doping is in the barrier and in both barrier and well, the MQW emission appears above the GaN band gap, while the sample doped in the well shows a redshifted emission. The redshift is attributed to the self-energy shift of the electron states due to the correlated motion of the electrons exposed to the fluctuating potential of the donor ions. At low temperature a longer PL decay time, 760ps, was measured for the sample doped in the well, a factor of 2 longer than for the barrier doped case. The difference is explained by the effect of interplay of free carriers and ions on the screening of the polarization field in these doped structures.