Исследование этапов превращения кремния в карбид кремния в процессе атомного замещения методами полного внешнего отражения рентгеновских лучей и рентгеновской дифрактомерии

X-ray diffraction and total external reflection of X-rays (X-ray reflectometry) methods were used to study the successive stages of synthesis of epitaxial SiC films on Si (100) X-ray diffraction and total external X-ray reflection (XRD) methods were used to study successive stages of synthesis of epitaxial SiC films on Si (100) surfaces, (110) and (111) surfaces by the atom substitution method. The data on the transformation evolution of (100) surfaces were studied, (110) and (111) Si, into SiC surfaces. A comparative analysis of the X-ray structural quality of the SiC layers grown on Si by the atom substitution method with the quality of SiC layers grown by Advanced Epi by the standard CVD method. A modified technique for the total outer X-ray reflection method, based on measurements of the intensity of the reflected X-rays using a special parabolic mirror. It is shown that the method of total external reflection method makes it possible to obtain important information about the degree of surface roughness of SiC layers, the evolution of their crystal structure and plasmon energy in the process of Si to SiC conversion.

Исследование сильно легированных эпитаксиальных пленок n-3C-SiC, выращенных методом сублимации на основе полуизолирующих подложек 6H-SiC

Heavily doped 3C-SiC films based on semi-insulating 6H-SiC substrates were obtained by sublimation epitaxy. The structural perfection of the obtained samples was monitored by X-ray diffractometry. The measurements of the photoluminescence and Hall effect spectra have confirmed the rather high perfection of the obtained epitaxial layers.

Comparative Study of High Temperature Anti-oxidation Property of Sputtering Deposited Stoichiometric and Si-rich SiC Films

Stoichiometric and silicon-rich (Si-rich) SiC films were deposited by Microwave Electron Cyclotron Resonance (MW-ECR) plasma enhanced RF magnetron sputtering method. As-deposited films were oxidized at 800, 900 and 1000 ℃ in air for 60 min. The chemical composition and structure of the films were analyzed by X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy and Fourier Transform Infrared spectroscopy (FT-IR). The surface morphology of the films before and after high temperature oxidation was measured by atomic force microscopy. The mechanical property of the films was measured by a Nano-indenter. The anti-oxidation temperature of the Si-rich SiC film is 100 ℃ higher than that of the stoichiometric SiC film. The oxidation layer thickness of the Si-rich SiC film is thinner than that of the stoichiometric SiC film in depth direction. The large amount of extra silicon in the Si-rich SiC film plays an important role in the improvement of its high temperature anti-oxidation property.

Preparation and Characterization of Pure SiC Ceramics by HTPVT Induced by Seeding with SiC Nanoarrays

Dense SiC ceramics were fabricated by high-temperature physical vapor transport (HTPVT) growth process using SiC nanoarrays as the crystal seeds, which was obtained by vacuum heat treatment of amorphous SiC films prepared by plasma-enhanced chemical vapor deposition (PECVD) with a porous anodic aluminum oxide (AAO) template. In the HTPVT process, two-step holding was adopted, and the temperature at the first step was controlled at 2100 and 2150 °C to avoid SiC nanoarrays evaporation, and the grain size of SiC crystal increased with the increase in temperature and decrease in the pressure of Ar. The temperature of the second step was 2300 °C, and rapid SiC grain growth and gradual densification were achieved. The prepared SiC ceramics exhibited a relative density of more than 99%, an average grain size of about 100 μm, a preferred orientation along the (0 0 0 6) plane, a Vickers hardness of about 29 GPa, a flexural strength of about 360 MPa, and thermal conductivity at room temperature of more than 200 W·m−1·K−1.

Structures, Electronic Properties and Carrier Transport Mechanisms of Si Nano-Crystalline Embedded in the Amorphous SiC Films with Various Si/C Ratios

Recent investigations of fundamental electronic properties (especially the carrier transport mechanisms) of Si nanocrystal embedded in the amorphous SiC films are highly desired in order to further develop their applications in nano-electronic and optoelectronic devices. Here, Boron-doped Si nanocrystals embedded in the amorphous SiC films were prepared by thermal annealing of Boron-doped amorphous Si-rich SiC films with various Si/C ratios. Carrier transport properties in combination with microstructural characteristics were investigated via temperature dependence Hall effect measurements. It should be pointed out that Hall mobilities, carrier concentrations as well as conductivities in films were increased with Si/C ratio, which could be reached to the maximum of 7.2 cm2/V∙s, 4.6 × 1019 cm−3 and 87.5 S∙cm−1, respectively. Notably, different kinds of carrier transport behaviors, such as Mott variable-range hopping, multiple phonon hopping, percolation hopping and thermally activation conduction that play an important role in the transport process, were identified within different temperature ranges (10 K~400 K) in the films of different Si/C ratio. The changes from Mott variable-range hopping process to thermally activation conduction process with temperature were observed and discussed in detail.

Simultaneous laser doping and annealing to form lateral p–n junction diode structure on silicon carbide films

Laser-assisted doping of intrinsic silicon carbide (SiC) films deposited on Si (100) substrates by pulsed laser deposition (PLD) method and its influence on simultaneous annealing of the thin film is studied. PLD grown intrinsic SiC films are transformed to p-type SiC and n-type SiC, using laser-assisted doping in aqueous aluminum chloride and phosphoric solutions, respectively. Simultaneous doping and annealing of the SiC film are observed during laser-assisted doping. By precisely positioning the selectively doped region, lateral p–n diodes are formed on the SiC films without using any mask. Electric characteristics confirmed the formation of a lateral p–n diode structure. Numerical analysis of temperature distribution along the depth of the SiC films explains the mechanism of simultaneous doping and annealing during the laser treatment.