Optical properties of heavily doped $\mathrm{G}\mathrm{a}\mathrm{N}/(\mathrm{A}\mathrm{l},\mathrm{G}\mathrm{a})\mathrm{N}$ multiple quantum wells grown on $6H-\mathrm{S}\mathrm{i}\mathrm{C}\left(0001\right)\mathrm{}$ by reactive molecular-beam epitaxy

We study, both experimentally and theoretically, the influence of polarization-induced electric fields on the optical properties of heavily doped $(7\mathrm{}\times {10}^{18}{\mathrm{cm}}^{\mathrm{-}3})$ $\mathrm{G}\mathrm{a}\mathrm{N}/(\mathrm{A}\mathrm{l},\mathrm{G}\mathrm{a})\mathrm{N}$ multiple-quantum-well structures. To investigate the impact of the strain state on the transition energy, these heterostructures are deposited on either a GaN or an (Al,Ga)N relaxed buffer layer. Furthermore, we show that the recombination dynamics in these heavily doped multiple quantum wells is still controlled by residual electric fields, contrary to the common assumption that flatband conditions are established at this doping level.