Defect evolution of nanocrystalline SnO2 thin films induced by pulsed delivery during in situ annealing

The microstructural defects of nanocrystalline SnO2 thin films prepared by pulsed laser deposition have been investigated using transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy. Defects inside nanocrystalline SnO2 thin films could be significantly reduced by in situ annealing SnO2 thin films at 300 deg. C for 2 h. High-resolution transmission electron microscopy showed that the stacking faults and twins were annihilated upon in situ annealing. In particular, the inside of the SnO2 nanoparticles demonstrated perfect lattices free of defects after in situ annealing. Raman spectra also confirmed that the in situ annealed specimen was almost defect-free. By using in situ annealing, defect-free nanocrystalline SnO2 thin films can be prepared in a simple and practical way, which holds the promise for applications as transparent electrodes and solid-state gas sensors.