Electronic band structure of GaN diluted and overdiluted with group-V elements

The technology for manufacturing $\mathrm{Ga}\mathrm{N}$-based devices is already very mature, but band engineering in this technology is still limited to mixing group-III elements, while the incorporation of group-V elements into $\mathrm{Ga}\mathrm{N}$ can create possibilities in band-gap engineering. In this work, we report comprehensive experimental studies of the electronic band structure for $\mathrm{As}$-diluted and overdiluted $\mathrm{Ga}\mathrm{N}\mathrm{As}$ supported by computational methods based on the state-of-the-art density-functional-theory (DFT) approach. These studies clearly demonstrated that the incorporation of arsenic into $\mathrm{Ga}\mathrm{N}$ modifies the valence band, while the conduction band remains undisturbed up to 8% arsenic content. For the first time, $\mathrm{As}$-related changes in the valence band are studied with high resolution in electron photoemission spectroscopy. $\mathrm{As}$-related narrowing of the energy gap is also detected in the absorption spectra. These experimental observations are very consistent with the calculations of the electronic band structure for $\mathrm{Ga}\mathrm{N}\mathrm{As}$, and therefore the same DFT approach was used to calculate the electronic band structure for $\mathrm{Ga}\mathrm{N}$ diluted and overdiluted with the remaining group-V elements, i.e., $\mathrm{Ga}\mathrm{NP}$, $\mathrm{Ga}\mathrm{N}\mathrm{Sb}$, and $\mathrm{Ga}\mathrm{N}\mathrm{Bi}$. In this case, it is also clearly visible that adding $\mathrm{P}$, $\mathrm{Sb}$, or $\mathrm{Bi}$ to $\mathrm{Ga}\mathrm{N}$ modifies the valence band, while the conduction band remains undisturbed when the V-group concentration does not exceed 5%.