Characterization of Si Nanocrystals in Superlattice Structure Grown by Plasma-enhanced Chemical Vapor Deposition
Date Issued
2015
Date
2015
Author(s)
Chu, Chien-Yu
Abstract
In this thesis, we have deposited superlattice thin films by Plasma enhanced chemical vapor deposition(PECVD), including two different kind of material: amorphous Si/silicon dioxide(a-Si/SiO2), silicon-rich oxide/silicon dioxide(SRO/SiO2). Followed by thermal annealing, an apparently ordered structure of silicon atomsand its diffraction pattern were observed by transmission electron microscopy (TEM), which verified the existence of Si-nanocrystals inside the superlattice thin film.Thecharacteristics ofSi-nanocrystals were also studiedby continuous-wave photoluminescence(PL) and time-resolved PL. In the superlattice structure, a-Si or SRO sub-layers were deposited in different thickness and different periodsto control the grand size of Si-nanocrystals. From the PL spectra, we can observe the increasingemission intensitywith the decreasing sub-layer thickness of the thin film, and thendecreasing of the intensity is followed. Blue shift is also observed, which means the grain size is decreasedand quantum confinement has affected the energy levels of Si-nanocrystals. The carrier lifetime also is influenced by the same effect, and can be characterized by time-resolved PL measurement.
Subjects
Si Nanocrystals
Superlattice
photoluminescence
Type
thesis
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