SrTiO₃（110） Surface Reconstruction And Its Influence To C₆₀ Molecular Self-assembly

Molecular self-assembly （MSA） is an effective pathway to prepare nanostructures.Understanding and controlling MSA of organic molecules on the substrate surface areessential to fabricate and optimize functional nanostructured materials. In this thesis，C₆₀and SrTiO₃（110）, C₆₀/STO（110）, as a model systems was investigated by scanningtunneling microscopy （STM）. Surface reconstruction of STO（110） was identified, and itsinfluence on C₆₀MSA was studied.First, surface reconstruction of STO（110） was studied as a function of preparationparameters. Due to the polar characteristic of STO（110） surface, enriched surfacereconstructions can be realized, and the final surface can be regulated by the amount ofAr+sputtering, annealing temperature as well as duration. Distinct STO（110）reconstruction surfaces then can be used as templates for MSA of organic molecules.Next, the MSA processes of C₆₀on different STO（110） templates were studied. Ourobservations showed that surface reconstruction has a pronouncing effect on C₆₀MSA.Specifically, on STO（110）（4×1） diline reconstruction surface, C₆₀chains were formedwith alternative height. The lower molecular chain was located on the diline, while thehigher molecular chain was located between two adjacent dilines; on STO（110）（5×1）triline reconstruction surface, C₆₀molecules tend to fall above on the two outer atom linesof trilines; on the STO（110）（n×8） blend structure, C₆₀chains formed preferentially in thegap of adjacent domains before locating above the domains. The lower molecular chaindeposited between neighboring （4×1） dilines, and the higher molecular chain formed overthe mixing structure. Our research confirmed that oxide nanostructured templates played acrucial role in controlling molecular self-assembly processes.