Comment on Infrared dielectric function of Ga(As,P) semiconductor alloys near the reststrahlen bands (Applied Physics Letters 123, 172102, 2023)

Though extensively studied since the emergence of zincblende cubic A(B,C) semiconductor alloys (zb-SCA) in the sixties, the phonon mode behavior of Ga(As,P) remains a subject of debate to this day. Recently Zollner and co-authors reported on a thorough far-infrared (IR) ellipsometry study of the vibrational spectra of Ga(As,P) spanning the composition domain. They suggest that their experimental data are better described by the cluster model than by our percolation model. On the basis of Zollner experimental data, kindly made available to us, we derive an improved version of the percolation model that explains the phonon mode behavior of Ga(As,P) beyond existing CM and PM approaches, with ab initio phonon calculations in support.