Deep-ultraviolet aperiodic-oscillation emission of AlGaN films.

In this Letter, we describe an aperiodic-oscillation emission phenomenon originating from the Fabry-Perot effect in the deep-ultraviolet backscattering fluorescence spectrum of the $c$c-plane AlGaN film, which is related to the dispersion of its ordinary refractive index near the band edge. Based on this fluorescence spectrum, the ordinary refractive index of the AlGaN film near the band edge could be directly obtained. Certainly, by means of variable angle spectroscopic ellipsometry, the ordinary refractive index of the AlGaN film could be also achieved. Comparing the results obtained by both methods, we discovered that the refractive indices are quite similar, which suggests that the aperiodic-oscillation fluorescence spectrum is also a reliable approach to capture the refractive index of anisotropic optical films.