  Here we have investigated the role of electron-phonon coupling on the Raman
spectrum of narrow bandgap semiconductors APd3O4 (A = Ca, Sr) and hole-doped
system Sr0.85Li0.15Pd3O4. Four Raman active phonons are observed at room
temperature for all three compounds as predicted by factor group analysis. The
lowest energy phonon (~190/202 cm-1) associated with Pd vibrations is observed
to exhibit an asymmetric Fano-like lineshape in all the three compounds,
indicating the presence of an interaction between the phonon and the electronic
continuum. The origin of the electronic continuum states and electron-phonon
coupling are discussed based on our laser power- and temperature-dependent
Raman results. We have observed an enhanced strength of electron-phonon
coupling in Sr0.85Li0.15Pd3O4 at low temperatures which can be attributed to
the metallicity in this doped compound.
