Электронографическое изучение структуры эпитаксиального графена, сформированного путем термического разложения SiC(0001) в атмосфере Ar и в высоком вакууме

The structure of epitaxial graphene formed by thermal destruction of silicon carbide surface in the conditions of vacuum synthesis and in an Ar environment has been studied by reflection electron diffraction. As a result of the conducted study it is found the notably more homogeneous graphene coating of buffer layer on the SiC surface under the graphene formation on the polytypes 4H- и 6H- SiC(0001) surfaces in the inert environment as against the graphene synthesis in vacuum. The dependence of quality of the covering from degree of initial single crystal perfection is shown.

Low Temperature Growth of 3C-SiC Film on Si (111) by Plasma Assisted CVD

In order to demonstrate the formation of 3C-SiC film on Si (111) at low substrate temperature, the effects of C3H8 on the crystallinity of the films on Si (111) have been investigated by changing the flow rate of C3H8 at the substrate temperature of 850 °C. Oriented polycrystalline 3C-SiC film grew under the C/Si of 3 – 5 with a-C. It is suggested that etching effects of growing surface by hydrogen radicals generated from C3H8 decomposition is lowered by lowering the substrate temperature. The crystallinity has been investigated by reflection electron diffraction (RED) and a X-ray diffraction (XRD). The thickness and the surface roughness of the films were investigated by an ellipsometric measurement.

Implications for Ultrafast Reflection Electron Diffraction from Temporal and Spatial Evolution of Transient Electric Fields

Understanding interaction of ultrafast pulsed laser with matter is critical for probing ultrafast processes in materials science, understanding the physics of laser ablation and the laser induced non-equilibrium carrier dynamics in metals and semiconductors, including plasmonics. When an intense laser pulse of femtoseconds (fs) in duration hits the surface of a targeted matter, it excites a hot electron gas. Part of the hot electrons is emitted from the surface in a way similar to thermionic emission. Electrons can also be emitted through multiphoton photoemission (MPPE) or thermally assisted MPPE. The emitted electrons travel at speeds that create transient electric fields (TEFs). To detect TEFs and study the dynamics of emitted electrons, we have developed a time resolved electron beam imaging technique that allows us to measure TEFs above a sample surface at picoseconds time resolution. We have also developed a model of the TEFs based on the propagation of emitted electrons and the percentage of electrons escaping from the surface. We examine the significance of TEFs for ultrafast reflection electron diffraction by examining anomalous effects in ultrafast reflection high energy electron diffraction (RHEED) of silicon surfaces.

Heteroepitaxial Growth of 3C-SiC on Si (111) at Low Substrate Temperature by Plasma Assisted CVD

In order to demonstrate the formation of 3C-SiC film on Si (111) at low substrate temperature, the effects of C3H8 on the crystallinity of the films on Si (111) have been investigated by changing the flow rate of C3H8 at the substrate temperature of 950 °C. Nearly single-crystalline 3C-SiC film grew under the ratio of the flow rate of C3H8 to the flow rate of SiH4 (C/Si) of 2 - 2.5. From these results, it is suggested that C/Si shifts into higher with decreasing the substrate temperature. The crystallinity has been investigated by a reflection electron diffraction (RED) and a X-ray diffraction (XRD). The thickness and the surface roughness of the films were investigated by an ellipsometric measurement.

Hetero-Epitaxial Growth of 3C-SiC on Si (111) by Plasma Assisted CVD

The effects of C3H8 on the microstructures of the films on Si (111) have been investigated by changing the concentration of C3H8 from 0.5% to 5%. 3C-SiC film on Si (111) grown at the C3H8 concentration of 1% with relatively high flow rate of SiH4 (30 sccm) is single crystal and free from the contamination of W2C. By comparing the deposition rates of the films on Si (111) and Si (100) at different concentrations of C3H8, SiC growth on Si (111) is much more dependent on C3H8 concentration than that on Si (100). From these results it is suggested that SiC growth on Si (111) is strongly influenced by hydrogen radicals generated from C3H8 decomposition by the plasma and forms single crystal easier than on Si(100). It is expected that 3C-SiC epitaxial growth on Si (111) has higher deposition rate and lower substrate temperature than on Si (100). The crystallinity has been investigated by a reflection electron diffraction (RED) and a X-ray diffraction (XRD). The thickness and the surface roughness of the films were investigated by an ellipsometric measurement.

Key Radicals for Hetero-Epitaxial Growth of 3C-SiC on Silicon Substrates

Effects of the flow rate of C3H8 passed through hydrogen plasma on deposition rates and^microstructures of 3C-SiC films on Si (100) substrate were investigated by a reflection electron diffraction, an X-ray diffraction and an ellipsometric measurement. The deposition rate of the films increased independently of the flow rate of C3H8 with increasing the flow rate of SiH4. The films grown with increasing the flow rate of C3H8 kept single crystalline structure even at high flow rate of SiH4. Hydrogen radicals generated from C3H8 decomposition by plasma increase with increasing the flow rate of C3H8, and play important rolls to keep epitaxial growth.