The photoluminescence (PL) properties of Si-doped cubic GaN with different carrier concentrations were investigated at room temperature. The epilayers were grown on GaAs (001) by radio-frequency molecular-beam epitaxy. It was found that when the carrier concentration is increased from ${\text{5×10}}^{15}$ to ${\text{2×10}}^{18} {\mathrm{cm}}^{\mathrm{-3}},$ the PL peak shifted towards low energy, from 3.246 to 3.227 eV, and the PL linewidth increased from 77.1 to 121 meV. The PL peak shift is explained by the band gap narrowing effect due to the high doping concentration. The PL linewidth includes two parts: one is doping concentration independent, which is caused by the imperfection of samples and phonon scattering; the other is doping concentration dependent. We assign the second part to the broadening by the microscopic fluctuation of the doping concentration. The experimental measurements are in good agreement with the model.

The Siberian Scoter (Melanitta stejnegeri) is a medium sea duck distinct from M. deglandi due to the absence of hybridization and differences in morphological characteristics. However, knowledge of its phylogenetic relationships within Anseriformes is limited due to a lack of molecular data. In this study, the complete mitogenome of M. stejnegeri was firstly sequenced, then annotated and used to reconstruct the phylogenetic relationships of 76 Anseriformes species. The complete mitogenome of M. stejnegeri is 16,631 bp and encodes 37 typical genes: 13 protein-coding genes, 2 ribosomal RNAs, 22 transfer RNAs, and 1 non-coding control region. Its mitogenome organization is similar to that of other Anseriformes species. The phylogenetic relationships within the genus Melanitta are initially clarified, with M. americana at the base. M. stejnegeri and M. deglandi are sister groups, clustering with M. fusca and M. perspicillata in order. Phylogenetic analysis suggests that Mareca falcata and M. strepera are sister groups, differing from previous studies. Results firstly indicate that Clangula hyemalis and Somateria mollissima are sister groups, suggesting a potentially skewed phylogenetic relationship may have been overlooked in earlier analyses relying solely on mitochondrial genomes. Our results provide new mitogenome data to support further phylogenetic and taxonomic studies of Anseriformes.