On the shift of the electroluminescence spectra of In$_x$Ga$_{1-x}$N/GaN structures with various indium contents and various substrate materials caused by the stark effect and mechanical stresses

The shift between the maxima of the electroluminescence spectra of In$_x$Ga$_{1-x}$N/GaN structures is measured at forward and reverse bias depending on the indium content $x$ in the quantum well and on the substrate material (SiC, AuSn/Si, and Al$_2$O$_3$). It is established that this shift increases as the indium concentration in the In$_x$Ga$_{1-x}$N layer and mechanical stresses from the substrate increase.