Cathodoluminescence defect characterization of hydrothermally grown SnO2 nanoparticles

Abstract

Sn O 2 nanoparticles in the 50–150nm size range were grown by a low temperature hydrothermal process, using SnCl4⋅5H2O as precursor and CH3(CH2)15N(Br)(CH3)3 as stabilizing agent. The as-grown samples were mostly amorphous and their crystallinity improved either by prolonged hydrothermal process or by air annealing at high temperatures. The absence of near-band-edge emission and appearance of a broad visible emission related mainly to oxygen vacancies and crystalline defects were the main characteristics of their room temperature cathodoluminescence (CL) spectra. A luminescent band in the 1.79–1.83eV spectral region was also detected. The intensity of the defect bands reduces both on prolonged hydrothermal treatment and air annealing at high temperatures, indicating a net decrease of defect content on thermal treatments. Panchromatic CL images revealed that most of the defect emissions come from smaller SnO2 nanoparticles.