Fig. 6

Literature data compilation. Direct comparison of the experimentally determined emission energies for the different nanodisc (ND) samples in the confinement regime (black squares) and the QCSE regime (red dots) to numeric results for GaN/AlN IFGARD quantum wells (QWs, black line) exhibiting totally shielded polarization fields (built-in field strength = 0 MV cm⁻¹). Error bars represent ND-thickness fluctuations of one monolayer GaN. Published values for pure GaN QWs with nonpolar growth directions are included as green squares^{26,57,58,59,67} and confirm the converging trend that is predicted for GaN QWs without built-in fields. While the conventionally grown [0001], fully polar GaN/AlN QWs^67–69 (red triangles) emit at much lower emission energies for well widths exceeding 1 nm. Even doping in the order of 5 × 10¹⁹cm⁻³ (red crosses) does not significantly alter the emission energies of the polar GaN/AlN QWs