Surface electron-phonon interaction of the nanocrystalline semiconductors

The combination of the surface photovoltaic and the photoacoustic techniques was used for probing the surface electron-phonon interaction (SEPI) and the mechanism of nonradiative transitions of the three typical nanocrystalline semiconductors at room temperature upon illumination of UV. near IR light. The results showed that the SEPIs on the La-doped nano-TiO₂ and the nano-La_1-xSr_xFeO₃ had nothing to do with the charge transfer transitions of the main bandgap. The SEPI of the nano-La_1-xSr_xFeO₃ depended close on both exciton transitions and crystal-field transitions upon illumination at the photon energy hnu was smaller than the bandgap E_{g, La 1-x Sr x FeO 3}. The photogenic free charge carriers at hnu<E_{g, TiO 2}, however, are partially or completely responsible for SEPI on the La-doped nano-TiO₂. The charge transports that relate to the heterostructure between CdTe and CdS layers resulted in both surface photovltage effect and SEPI on the MPA-capped CdTe nanoparticles at hnugesE_g, _CdTe.