Significance of in-plane oxygen vacancy rich non-stoichiometric layer towards unusual high dielectric constant in nano-structured SnO2

Highlights: • SnO₂ QDs utilized for preparing two types SnO₂ NPs by annealing in presence and absence of oxygen. • Spectroscopic determination of non-stoichiometric layer exclusively in Ar annealed sample. • Elucidation of presence of in-plane oxygen defects influencing dielectric property in NPs. • Establishing correlations of oxygen defects for anomalous dielectric property in SnO₂ NPs. Influence of non stoichiometric layer to the possible contribution towards the unusually high dielectric constant of n-type SnO₂ is discussed. Oxygen deficient and oxygen rich environments during the growth of SnO₂ nanoparticles synthesized from the as prepared SnO₂ quantum dots (QDs) of ∼2.4 nm have enabled creation of various defects states; however, it results to similar dimension of NPs. Defects states bring in strong changes in dielectric property including other electrical properties. Oxygen vacancies related defects have been spectroscopically elucidated using Raman spectroscopy and photoluminescence measurements. The study offers a plausible correlation between oxygen vacancies and unusually high dielectric constant of SnO_2. In-plane oxygen vacancy is found to be responsible for enhanced dielectic value. The understanding of phenomena involved in the colossal permittivity can be utilized for tuning and the engineering of the macroscopic device applications.