Resonant light scattering by optical phonons in a homoepitxial $n$-GaP nanolayer grown on a (001)$n$-GaP substrate

The results of detection of resonant amplification of light scattering intensity by optical phonons in a homoepitaxial nanoscale 70 nm thick $n$-GaP layer grown by gas-phase epitaxy from organometallic compounds on a conducting strongly doped $n$-GaP crystal substrate oriented along the (001) axis have been presented. It has been shown that it is possible to detect rather narrow bands of second-order light scattering lines in the frequency range from 600 to 800 cm$^{-1}$ at room temperature in the Raman light scattering spectrum of such a (001)$n$-GaP nanolayer in the $n$-GaP/$n$-GaP (001) sample in comparison with those in the spectrum of a high-resistance (001)$si$-GaP crystal sample. It has been established that such bands are caused by the total combinations and overtones of transverse TO($\Gamma$) and longitudinal LO($\Gamma$) optical phonons with wave vectors corresponding to the points $\Sigma$, K, X, L, and $\Gamma$ of the Brillouin zone of a GaP crystal. It has been shown that the light scattering is resonant and caused by the presence of impurities because of the exciton-phonon interaction.