X-ray absorption spectroscopy and Eu3+-emission characteristics in GaAs/SnO2 heterostructure

Cristina Bueno (1) , Aline Y. Ramos (2) , Aude Bailly (3) , Eric Mossang (4) , Luis Scalvi (1)

1 UNESP - Universidade Estadual Paulista Júlio de Mesquita Filho = São Paulo State University
2 NEEL - MRS - Matériaux, Rayonnements, Structure
3 NEEL - SIN - Surfaces, Interfaces et Nanostructures
4 NEEL - X'Press - X'Press : diffraction et hautes pressions

X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data are used for investigating heterostructure samples of GaAs/SnO2. XANES data are used for analyzing the local organization around Eu in the heterostructure formed by GaAs and Eu-doped SnO2. The differences between the XANES data for these samples and data obtained for Eu-doped SnO2 thin films, deposited on glass substrate, are assumed as responsible for the dif- ferences in the photoluminescence (PL) spectra concerning the Eu3+ emission, since films deposited on glass substrate do not present Eu3+ PL transitions until the annealing temperature is rather high. Eu3+ emission is explored using two different excitation sources: 350 nm from a Kr+ laser (above SnO2 energy bandgap) and 488 nm from an Ar+ laser (below SnO2 bandgap energy). The existence of more organized regions around the Eu3+ site observed for the heterostructure surface may be associated with the Eu3+ luminescent emission. The main and secondary features in the XANES show that there are differences in the average local Eu environment for the SnO2:Eu isolated thin films and heterostructures, being more organized in the latter. Electrical characterization evidences that the portion of the resistivity reduction that corresponds to photo-ionized intrabandgap states is responsible for the persistent photoconductivity phenomenon in the heterostructures.

Domaines: Matériaux

Cristina Bueno, Aline Y. Ramos, Aude Bailly, Eric Mossang, Luis Scalvi. X-ray absorption spectroscopy and Eu3+-emission characteristics in GaAs/SnO2 heterostructure. SN Applied Sciences, 2020, 2 (9), pp.1579. ⟨10.1007/s42452-020-03344-3⟩. ⟨hal-02936162⟩