R. Mauricot et al., PHOTOCONDUCTIVITY OF THE UNDOPED GAMMA-CE2S3 AND DOPED GAMMA-[NA]CE-2-S-3 RARE-EARTH SESQUISULFIDES, Materials research bulletin, 31(3), 1996, pp. 263-269
This paper reports the spectral responses of the steady-state and modu
lated photoconductivity in undoped gamma-Ce2S3 single crystals and pre
ssed powder pellets and the modulated photoconductivity in doped gamma
-[Na]Ce2S3 (Na/Ce = 0%, 5%, 12%, and 20%) pressed powder pellets. Thei
r analysis clearly indicates the presence of several levels between th
e valence and conduction bands. Taking into account the temperature de
pendence of the spectral responses and the electron lifetimes that cou
ld be estimated, a band structure model is proposed for gamma-Ce2S3 se
squisulfide, discriminating between defect levels and cerium 4f levels
. The influence of the substitution/insertion of sodium on the electro
nic structure is also discussed.