M. Rosch et al., RESONANT RAMAN-SCATTERING IN A ZERO-GAP SEMICONDUCTOR - INTERFERENCE EFFECTS AND DEFORMATION POTENTIALS AT THE E(1) AND E(1)+DELTA(1) GAPS OF HGTE, Physical review. B, Condensed matter, 49(19), 1994, pp. 13460-13474
The efficiency of resonant Raman scattering by TO and LO phonons in mo
lecular-beam epitaxially grown HgTe is studied for (001), (110), and (
111) surfaces with incident photon energies near the E1 and E1 + DELTA
1 band gaps. Absolute values of the Raman scattering efficiency are ob
tained by means of a sample substitution method and by correcting the
experimental data with respect to absorption and reflection losses of
the incident and the scattered radiation as well as the different angl
es of collection inside and outside the sample. We compare our results
with calculated resonance profiles assuming uncorrelated electron-hol
e pairs as intermediate states. Interference effects between dipole-al
lowed (deformation-potential and electro-optic coupling) and dipole-fo
rbidden scattering by LO phonons in HgTe (001) are used to separate ex
trinsic (electron-impurity interaction) from intrinsic contributions (
Frohlich intraband coupling) to dipole-forbidden scattering. The optic
al deformation potentials near the E1 and E1+DELTA1 gaps are obtained
from TO scattering in HgTe (111) [HgTe (110)] to be d1,o5 = -19.9 eV (
-21.9 eV) and d3,o5 = 14.7 eV (13.0 eV). The Faust-Henry coefficient o
f HgTe is determined.