研究目的
Investigating the synthesis and growth mechanism of 3C-SiC nanowires containing reduced amount of C, grown on single-crystal Si via pyrolysis of polycarbosilane (PCS) by adjusting pyrolysis temperature and precursor.
研究成果
The study successfully synthesized pure and carbon-poor SiC nanowires via the vapor-liquid-solid growth mechanism. The properties of SiC nanowires are significantly affected by the properties and content of carbon-bond, while carbon content itself is substantially influenced by the precursor pyrolysis temperature and state. The investigation provides new insights into the formation and the morphology of carbon-poor SiC nanowires.
研究不足
The technical and application constraints of the experiments include the inability to accurately regulate SiC nanostructures at the atomic and molecular scales, high growth temperature leading to process instability, and the presence of many defects in the structure and high surface C content in nanowires prepared via common methods.
1：Experimental Design and Method Selection:
The preparation process of SiC nanowires is mainly divided into two steps: the wafer pretreatment and the preparation of nanowires. Single-crystal Si (100) wafer with a 300 nm oxide layer was chosen as the substrate for the growth of nanowires. In the first step, the Si wafer was ultrasonically cleaned in absolute ethanol and deionized water to remove impurities. This was followed by an ion-beam assisted deposition (IBAD) on a single-crystal Si substrate to deposit a certain thickness of Ni thin film as a catalyst. In the second step, the precursor polycarbosilane (PCS) is placed in the crucible, whereas the coated single crystal Si substrate is placed flat in the downstream position of the precursor in the tube furnace. The air in the furnace was completely replaced by Ar. The Ar gas flow rate was stabilized at 40 sccm. The temperature was raised to 1300°C at a rate of 5°C/min and held for 2 h. After the end of the heat preservation, the furnace was naturally cooled to room temperature by just turning the power off.
2：Sample Selection and Data Sources:
Single-crystal Si (100) wafer with a 300 nm oxide layer was used as the substrate.
3：List of Experimental Equipment and Materials:
Tube furnace, X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), confocal Raman microscope, Fourier-transform infrared spectrometer (FTIR).
4：Experimental Procedures and Operational Workflow:
The preparation process involved wafer pretreatment and nanowire preparation, as described above.
5：Data Analysis Methods:
The phase composition, morphology, and microstructure of the products were analyzed via XRD, SEM, and TEM, respectively. The C phase of the nanowires was characterized using a confocal Raman microscope. The chemical-bond change was qualitatively and quantitatively analyzed using FTIR.
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