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Crystalline carbon-nitride films prepared by reactive radio frequency magnetron sputtering
Author
Li, Han Shi
Supervisor
Xu, Shuyan
Abstract
The significance and motivation of research on synthesis of a novel material, PC3N4 were reviewed. It is seen that this subject is both fundamentally and technologically significant and presents a great challenge to condensed matter physicists, material scientists and chemists as well. Liu and Cohen's prediction that a type of carbon nitride compound, β-C3N4. is comparable in hardness with or even harder than diamond, was also conceptionally described.
The progress and current status of research on this novel material were selectively described, showing that much progress had been achieved, particularly in four years before.
Based on physical and technical considerations, a reactive d magnetron sputtering was chosen as a technique to synthesise carbon nitride films in this experiment. The general principle of magnetron sputtering, and the structure and main features of the present purpose-designed rf magnetron sputtering equipment were briefly described. Using this equipment, the carbon nitride films were successfully deposited on various substrates, such as single- crystal KC1 (100), KBr (100) and Si (100) substrates, and stainless steel and glass wafers. The morphology, chemical bond states and compositions, structures and microstructures of these films were characterised by means of various analyses, such as infrared spectrum (IR), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), transmission electron microscopy (TEM), high resolution electron microscopy (HREM), x-ray diffraction (XRD) and atomic force microscopy (AFM).
The main findings in our experiment are summarised as follows.
1. The films deposited on single-crystal KBr (100), KC1 (100) and Si (100) substrates were of polycrystalline structure whereas the films on stainless steel wafers were amorphous.
2. CN grains with various sizes were distributed in different regions of the polycrystalline films. And the biggest grain was estimated to be over 10 μm in size.
3. Nitrogen atoms were bonded to carbon atoms and the composition ratio N/C for C3N4 component reached 1.23 in bulk and 1.27 at surface. These numbers were close to the expected stoichiometric value of 1.33, indicating a high quality of the film both in bulk and at surface.
4. The observed Laue patterns, Kikuchi lines, and HREM images exhibited that the observed CN grains were of single-crystalline and perfect structure.
5. The composition ratio both for overall nitrogen and carbon contents and for C3N4 component increased respectively up to saturation values, 0.87 and 1.24 in the bulk of the film deposited on Si (100) substrate.
6. The time behaviours of the composition ratio NIC measured by XPS, the C-N bonding states revealed in IR spectra and the measured growth rate of the C-N film were well consistent with each other. The deposition condition for improving the C-N film quality was recommended.
Notably, this is the first time that polycrystalline C3N4 films were successfully prepared by means of reactive rf magnetron sputtering. And some results about the film structure were acquired from those films also for the first time.
Finally, some important issues in the research on carbon nitride film were reviewed and some subjects were also suggested for further study.
The progress and current status of research on this novel material were selectively described, showing that much progress had been achieved, particularly in four years before.
Based on physical and technical considerations, a reactive d magnetron sputtering was chosen as a technique to synthesise carbon nitride films in this experiment. The general principle of magnetron sputtering, and the structure and main features of the present purpose-designed rf magnetron sputtering equipment were briefly described. Using this equipment, the carbon nitride films were successfully deposited on various substrates, such as single- crystal KC1 (100), KBr (100) and Si (100) substrates, and stainless steel and glass wafers. The morphology, chemical bond states and compositions, structures and microstructures of these films were characterised by means of various analyses, such as infrared spectrum (IR), x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), transmission electron microscopy (TEM), high resolution electron microscopy (HREM), x-ray diffraction (XRD) and atomic force microscopy (AFM).
The main findings in our experiment are summarised as follows.
1. The films deposited on single-crystal KBr (100), KC1 (100) and Si (100) substrates were of polycrystalline structure whereas the films on stainless steel wafers were amorphous.
2. CN grains with various sizes were distributed in different regions of the polycrystalline films. And the biggest grain was estimated to be over 10 μm in size.
3. Nitrogen atoms were bonded to carbon atoms and the composition ratio N/C for C3N4 component reached 1.23 in bulk and 1.27 at surface. These numbers were close to the expected stoichiometric value of 1.33, indicating a high quality of the film both in bulk and at surface.
4. The observed Laue patterns, Kikuchi lines, and HREM images exhibited that the observed CN grains were of single-crystalline and perfect structure.
5. The composition ratio both for overall nitrogen and carbon contents and for C3N4 component increased respectively up to saturation values, 0.87 and 1.24 in the bulk of the film deposited on Si (100) substrate.
6. The time behaviours of the composition ratio NIC measured by XPS, the C-N bonding states revealed in IR spectra and the measured growth rate of the C-N film were well consistent with each other. The deposition condition for improving the C-N film quality was recommended.
Notably, this is the first time that polycrystalline C3N4 films were successfully prepared by means of reactive rf magnetron sputtering. And some results about the film structure were acquired from those films also for the first time.
Finally, some important issues in the research on carbon nitride film were reviewed and some subjects were also suggested for further study.
Date Issued
1999
Call Number
TP873.5.D5 Li
Date Submitted
1999