Comment on "Radiative and nonradiative recombination of bound excitons in GaP:N. I. Temperature behavior of zero-phonon line and phonon sidebands of bound excitons" and "Radiative and nonradiative recombination of bound excitons in GaP:N. IV. Formation of phonon sidebands of bound excitons"

We point out that the experimental data on the temperature dependence of the LO-phonon sidebands of NN4-6 in a recent paper by X. Zhang et al. [Phys. Rev. B 41, 1376 (1990)] are incorrectly analyzed, and that the theory in a closely related paper by Q. Hong, X. Zhang, and K. Dou [Phys. Rev. B 41, 2931 (1990)] is inadequate for explaining the LO-phonon sideband structure and temperature behavior of N-related bound excitons in GaP.