Development of Advanced Pulsed-Laser Deposition and application to Functional Materials

• Main Authors: Chih-Ping Yen, 嚴治平
• Other Authors: Jyhpyng Wang
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/bfru4c

博士 === 國立臺灣大學 === 物理學研究所 === 106 === In this thesis, potential of pulsed laser deposition PLD) to grow functional materials, such as crystalline hermal-unstable material (FeCO3), organic dyes (melanin, YD2-o-C8 and N3) and transitional metal oxide (Fe2O3-x) have been demonstrated by controlling laser-matter interaction and plasma-ambience interaction precisely. Furthermore, characteristics of electrocatalyst (NixFe1-xOy) was investigated as function of composition and the film thickness by using a new and facile chemical bath deposition (CBD). The Key for growing strongly textured FeCO3 thin films on substrates is to take advantage of the transient high temperature provided from plasma plume generated by ultrafast-pulsed laser. The thin film morphology and crystallinity are found to be significantly affected together by deposition rate. The results show that, when the peak deposition flux is lower than 0.03 nm/pulse, single-oriented crystallinity experiment can be achieved with roughness smaller than 50 nm. Matrix-assisted pulsed laser evaporation (MAPLE) is a popular form of PLD for deposition of organic materials. However because organic materials may decomposed under light, water vapour and heat. There exist few workable methods for growing organic thin films. Methods, such as dip coating and spin coating, may not be suitable for preparing large-area samples. To solve the problem, the possibility of using MAPLE as a deposition method of organic materials was studied. By comparing experiments on melanin, YD2-o-C8 and N3, the dye-sensitized solar cell (DSSC) using YD2-o-C8 shows energy conversion efficiency of 1.47% which is comparable to traditional method. A new and facile chemical bath deposition (CBD) of NixFe1-xOy electrocatalyst and application to PLD-prepared Fe2O3-x (hematite) photoanode for solar hydrogen production are presented. The optimization of photoelectrochemical efficiency is achieved via integration of PLD and CBD. At the PLD stage, the oxygen deficiency in hametite was controlled by using backfilled oxygen. At the CBD stage, the Ni-to-Fe ratio and electrolyte layer thickness are optimized. The dependence of the electrochemical and photoelectrochemical characteristics of the photoanode on the composition and the film thickness of the electrocatalyst was studied systematically and explained based on energy level diagrams and kinetics.