In-situ observation on oxidation process of Zn dots coherently grown on Si (111) by second harmonic generation

Abstract

It is a significant issue to research the oxidation process and mechanisms of metallic nanoparticles When the nanoscale metallic components are oxidized it will damage their functions and life time Particularly metallic nanoparticles are grown on the semiconductor components as contacts or interconnects The oxidation may result in the relaxation or void defects of metal nanocontacts and then reduce the conductivity It is important to study structural changes of metallic nanoparticles grown on the substrate and their interface after oxidation We used strategic RF magnetron sputtering to fabricate Zinc quantum dots coherently grown on the Si (111) substrate and in-situ analyzed the oxidation process of Zn quantum dots by reflective second harmonic generation (RSHG) Fully constrained Zn dots and sequent oxidized ZnO shell contributed 3m symmetrical dipole to RSHG pattern The spot area of pump laser would cover more than 109 dots and exhibited net symmetrical dipole contribution to RSHG pattern which depended on the constrain degree of Zn quantum dots constrained Si (111) The oxidation phenomena would lead to the reduction of Zn core and relax the stress between Zn dots and Si (111) which caused the change in RSHG pattern Synchrotron X-ray diffraction (XRD) patterns could confirm RSHG result and give the evolution of all possible crystal orientations in the oxidization Besides we utilized the field emission - scanning electron microscope (FE-SEM) to observe the micrographs and the depth scan of X-ray photoelectron spectroscopy (XPS) spectra to realize the microstructure of Zn/ZnO core-shell quantum dots via oxidation respectively As a result we further solve the key problem of the oxidation of metallic dots grown on semiconductor as the reference of nano device in the future

Date of Award	2016 Aug 18
Original language	English
Supervisor	Kuang-Yao Lo (Supervisor)