Surface electron-phonon interaction of the nanocrystalline semiconductors

摘要

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-La1-xSrxFeO3 had nothing to do with the charge transfer transitions of the main bandgap. The SEPI of the nano-La1-xSrxFeO3 depended close on both exciton transitions and crystal-field transitions upon illumination at the photon energy hυ was smaller than the bandgap Eg, La1-xSrxFeO3. The photogenic free charge carriers at hυ ≪ Eg,TiO2, 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 hυ⩾ Eg, CdTe.