Using metallic nanoclusters to develop nanostructured optoelectronic devices and highly sensitive bio-sensors on papers
Date Issued
2012
Date
2012
Author(s)
Tseng, Shao-Chin
Abstract
The purpose of this study is using metallic nanoclusters (NCs) and nanoparticles (NPs) to develop one-dimensional nanostructures, optical storage medium and biosensing test papers. In the first part of this thesis, we use NCs to develop antireflection structure performed by unique Si structures of ultrahigh density and very narrow diameter (ca. 10 nm). By using intruded “atomic-scale” Au NCs which are highly active catalysts within Si wafers during etching, we are capable to produce Si nano-stalactite (SNS) structures of ultrahigh density via controlling etching time. The SNS structures of ultrahigh density and shallow depth, which are different from one-dimensional nanostructures reported before, appear quite low reflectance from ultraviolet (UV) to near-infrared (NIR) regime. We find the intruded metallic NCs are more catalytic than self-assembled NPs and electroless-deposited metal catalysts. The better performance comes from larger contact area of intruded NC catalysts because of its atomic-scale size. Furthermore, we discuss the field emission property of the SNS structure. By comparing field emission properties between nanowire and SNS structure, we find that the turn-on field of SNS structure (9.5V/μm) is far less than that of nanowire (18V/μm).
In the second part of this thesis, we design an optical storage medium and its application by using Au NP as etching area and Au thin film as protective area. First, we study the photothermal effect induced by KrF excimer laser illumination, which induces metal thin film to transform into particles. This laser-induced photothermal effect is use to design a brand new optical permanent storage medium. Absorbance of common metal in UV regime is much higher than that in infrared regime. Thus, particle array can be formed by annealing process in selected area on metal thin film where the absorbed energy of metal in deep-UV (DUV) regime transform into heat. Combining unique catalytic ability of NPs and protective thin metal film on Si substrate, a further etching process can thus fabricate a high contrast, broad band and long-lasting optical storage medium. Besides, we display that this optical storage system can record data with sub-micrometer resolution and can be read out by DUV. And this optical storage medium can store several times denser than conventional blu-ray digital video disc (DVD).
Convenient, rapid, and accurate detection of chemical and biomolecules would be a great benefit to medical, pharmaceutical and environmental science. Many chemical and biosensors based on metal NPs have been developed. However, as a result of the inconvenience and complexity of most of the current preparation techniques, surface plasmon–based test papers are not as common as, for example, litmus paper, which finds daily use. In this paper, we propose a convenient and practical technique—based on the photothermal effect—to fabricate the plasmonic test paper. This technique is superior to other reported methods for its rapid fabrication time (a few seconds), large-area throughput, selectivity in the positioning of the NPs, and the capability of preparing NP arrays in high density on various paper substrates. In addition to their low cost, portability, flexibility, and biodegradability, plasmonic test paper can be burned after detecting contagious biomolecules—making them safe and eco-friendly.
In the fourth part of this thesis, we developed a new method—based on laser-induced jets of nanoparticles (NPs) and air drag forces—to select the particle size and density of NP arrays. We then exploited air drag forces to select NPs with sizes ranging from 5 to 50 nm at different captured distances. We further calculated the relationship between the air drag force and the diameter of the NPs to provide good control over the NP size by varying the capture distance. Laser-induced jets of NPs could also be used to fabricate NP arrays on a variety of substrates, including Si, glass, plastic, and paper. This method has the attractive features of allowing rapid, large-area preparation, with ready control over particle size, and with high selectivity in the positioning of NP arrays. In the last, we used this method to prepare both large NP arrays, to act hot spots on surface-enhanced Raman scattering–active substrates, and small NP arrays, to act as metal catalysts for constructing low-reflection, broadband light trapping nanostructures on Si substrates.
Subjects
nanoclusters
nanoparticles
one-dimensional nanostructures
localized surface plasmon resonance
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-101-D96527023-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):147f25ed65be8f08bc02c35fdcb6ca56