Raman Scattering and Field Emission Properties of One-Dimensional Nanosized Structure of IrO2 and RuO2
Date Issued
2004
Date
2004
Author(s)
Cheng, Chung-Liang
DOI
en-US
Abstract
Abstract
In this thesis, the Raman scattering and field-emission properties of one-dimensional transition-metal oxides like nanotubes or nanorods are reported. Due to their nanoscale size, shape and large surface-to-volume ratio, they behave quite differently from the bulk materials in the optical performance. They are presented as follows.
I. Raman spectra and field emission of IrO2 nanorods
Raman spectra and field emission measurement of IrO2 nanorods grown by metalorganic chemical vapor deposition (MOCVD) are reported. Red-shift and broadening of the linwidth of Raman spectra are observed. The peak positions and linewidth of the Raman features varied for IrO2 nanorods(tube-like) deposited on different substrate. These differences may indicate the existence of strain between IrO2 nanorods(tube-like) and the substrates. We also report on field-emission properties of conductive IrO2 nanorods. The unique geometrical features of IrO2 nanorods, including nanosized structure and self-assembled sharp tip, exhibit a strong effect on field enhancement (β=355), which result in a low threshold field (Eth=6.5 V/μm) defined at the beginning of emission. A low turn-on field for driving a current of 10 μA/cm2 is about 9.9 V/μm, which is comparable with the amorphous carbon. The potential of using IrO2 nanorods as an emitter material has been demonstrated.
II. Raman spectra and field emission of RuO2 nanorods
We report a detailed Raman Scattering study of RuO2 nanorods deposited on LiTaO3 substrate by MOCVD. Red-shift, broadening of linewidth and asymmetry of Raman spectra are observed. The lineshape of the Raman features are analyzed by the phonon confinement model. Phonon confinement effect was used to explain the experimental results of observed phonon modes. We also report on field-emission properties of conductive RuO2 nanorods. The unique geometrical features of RuO2 nanorods, including nanosized structure, exhibit a strong effect on field enhancement (β=1153), which result in a low threshold field (Eth=4.9 V/μm) defined at the beginning of emission. A low turn-on field for driving a current of 10 μA/cm2 is about 10.3 V/μm, which is comparable with amorphous carbon. The potential of using RuO2 nanorods as an emitter material has been demonstrated.
Subjects
二氧化釕
二氧化銥
拉曼散射
場發射
Field Emission
RuO2
IrO2
Raman Scattering
Type
thesis
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