Piezospectroscopic determination of the ratio of the electron-phonon to hole-phonon scattering matrix elements for LA and TA phonons in GaP

Abstract

An investigation of the stress dependence of the amplitude of the normalized wavelength-modulated absorption spectra of the phonon-assisted (LA, TA, and TO) indirect transition in GaP at 77 K has been performed. Theoretical expressions, which include the stress-dependent mixing between the top of the valence band (${\Gamma }_{8,v}$) and its spin-orbit splitoff band (${\Gamma }_{7,v}$) have been calculated for the intensities of the allowed phonon-assisted (LA, TA, TO, and LO) transitions. From the experimental results for $\overrightarrow{\mathrm{X}}\parallel \mathrm{}\left[111\right]\mathrm{}$ and $\overrightarrow{\mathrm{X}}\parallel \mathrm{}\left[001\right]\mathrm{}$, and the above theoretical expressions, the ratio of the electron-phonon ($e$-ph) to hole-phonon ($h$-ph) scattering matrix elements has been obtained for the LA and TA phonons. For the LA phonon the ratio was found to be $\frac{S_{{e-\mathrm{ph}}_{\mathrm{LA}}}}{S_{{h-\mathrm{ph}}_{\mathrm{LA}}}}=0.6\mathrm{}$ and for the TA phonon $\frac{S_{{e-\mathrm{ph}}_{\mathrm{TA}}}}{S_{{h-\mathrm{ph}}_{\mathrm{TA}}}}=1.1\mathrm{}$.