Raman study of the quantum interference of multiple discrete states and a continuum of states in the phonon energy region of semiconductors: examples of p-type Ga0.5In0.5P films

Abstract

Although the Fano quantum interference of one longitudinal optical (LO) phonon mode and one electronic continuum of states due to inter-valence band transition has been investigated by the Raman spectra, there is no observation of the interference of multiple phonon modes despite its potential for electromagnetically induced transparency in the far infrared region. In this study, p-type Ga0.5In0.5P films with two main LO modes in the same plane of atomic vibration and one more mode due to CuPt-type ordering are investigated. Asymmetric line profiles, peak energy shifts and peak broadenings in the Raman spectra are analyzed, and the destructive quantum interference of these LO-continuum systems are observed. Discussion with the reference data of p-type GaAs and Si for the one-LO mode system reveals that the asymmetry parameter features the derivatives of the density of the continuum of states in the vicinity of the LO phonon energies and the degree of the electric polarization. It is found experimentally that the interaction between the two main LO modes through the interactions with the continuum states takes place. A1(LO) mode due to the ordering affects the spectrum, however the interaction with the main two LO modes through the continuum is small. On the basis of the experimental result, the spectrum features for this alloy with greater hole density are estimated, where the various controls of the absorption spectrum in the phonon energy region are predicted.