Absorption and electroabsorption near the indirect edge of GaSe

Abstract Absorption and electroabsorption spectra have been measured near the indirect edge of the layer semiconductor GaSe. The experimental structures observed at 1.5 K are ascribed to the indirect excitonic transition with emission of different phonons. The determination of the threshold energy of the no-phonon indirect absorption process affords the energies of the phonons involved in the indirect transition to be derived.