Papers by Keyword: 3C-SiC

Abstract: The 3C-6H polytypic transition in 3C-SiC single crystals is studied by means of diffuse X-ray scattering (DXS) coupled with transmission electron microscopy (TEM). TEM reveals that the partially transformed SiC crystals contain regions of significantly transformed SiC (characterized by a high density of stacking faults) co-existing with regions of pure 3C-SiC. The simulation of the diffuse intensity allows to determine both the volume fraction of transformed material and the transformation level within these regions. It is further shown that the evolution with time and temperature of the transition implies the multiplication and glide of partial dislocations, the kinetics of which are quantified by means of DXS.

Abstract: This paper characterizes Al, N doped and undoped 3C-SiC samples after pulsed excimer laser anneal by using X-ray diffraction (XRD) and atomic force microscopy (AFM). In order to protect surface morphology, low energy density of 0.2444 J/cm2 per shot was applied to Al and N doped samples. The results show damage recovery is corresponding to the amount of total energy applied to the surface. The peak shift of Bragg diffraction spectra of Al doped samples are almost independent of the amount of total energy. As the energy density is reduced to 0.0667 J/cm2 per shot and applied to undoped samples, the peaks of Bragg diffraction spectra of undoped samples are shifted. However, the peaks of Bragg diffraction spectra of undoped samples annealed with combination of energy densities of 0.0667 and 0.2444 J/cm2 are not shifted.

Abstract: To demonstrate the formation of 3C-SiC film on Si (111) at low substrate temperature, the effects of C₃H₈ on the crystalline quality of the 3C-SiC films on Si (111) have been investigated by changing the flow rate of C₃H₈ at the substrate temperature of 950 °C. The crystalline quality has been investigated by transmission electron microscope and X-ray diffraction. 3C-SiC is epitaxially grown on Si(111) and the 3C-SiC films are in either near single crystalline or highly oriented form with stacking faults and twin. It is expected that the film with good crystalline quality may grow at around 2.5 in the ratio of the flow rate of C₃H₈ to SiH₄ and any microstructures of 3C-SiC films on Si (111) can be controlled by accurately controlling the ratio of C/Si.

Abstract: We report on experimental explorations of using focused ion beam (FIB) nanomachining of different types of silicon carbide (SiC) thin membranes, for making robust, high-quality stencil masks for new emerging options of nanoscale patterning. Using thin films and membranes in polycrystalline SiC (poly-SiC), 3C-SiC, and amorphous SiC (a-SiC) with thicknesses in the range of t~250nm−1.6μm, we have prototyped a series of stencil masks, with nanoscale features routinely down to ~100nm.

Abstract: This study has been focused on 3C-SiC epitaxial growth on 4H-SiC (0001) on-axis substrates using the standard CVD chemistry. Several growth parameters were investigated, including growth temperature, in-situ etching process and C/Si ratio. High quality single domain 3C epilayers could be obtained around 1350 °C, with propane present during pre-growth etching and when the C/Si ratio was equal to 1. The best grown layer is 100% 3C-SiC and single domain. The net n-type background doping is around 2x10¹⁶ cm^-3. The surface roughness of the layers from AFM analysis is in the 3 to 8 nm range on a 50x50 μm2 area.

Abstract: We obtained excess carrier lifetime maps by the microwave photoconductivity decay (µ-PCD) method in a free-standing n-type 3C-SiC wafer, and then we compared the lifetime maps with distributions of strains and defects observed by the optical microscopy and the Raman spectroscopy. We found that the excess carrier lifetimes are short in a strained region in 3C-SiC, which indicates that structural defects exist around a strained region.

Abstract: By conducting a heteroepitaxy of a 3C-SiC film on a Si substrate and by annealing its surface in a UHV ambient, epitaxial graphene can be formed on such 3C-SiC virtual substrates. While the growth on the Si-terminated 3C-SiC(111)/Si (111) surface is known to proceed in a similar manner as on the Si-terminated 6H-SiC(0001) surface, successful growth of graphene on 3C-SiC(100)/Si (100) and 3C-SiC(110)/Si (110) surfaces remains puzzling. We have carried out detailed cross-sectional transmission-electron-microscopy observations on these systems to find out that (111)-facets may play crucial roles in the initiation of graphene on these surfaces. This observation also accounts for the absence of the interface layer at the graphene/SiC in these orientations.

Abstract: A detailed experimental study of the mean and gradient stress, existing in the as-grown cubic silicon carbide epilayers, is presented in this paper. (100) and (111) oriented epiwafers with considerable film thickness variation have been elaborated using a horizontal low pressure chemical vapor deposition reactor. The mean and gradient stress within the 3C-SiC film were estimated from the static mechanical deformation of micromachined clamped-free beams. For both studied orientations, we observe a stress gradient inversion phenomenon that can be explained in terms of creep occurring in 3C-SiC film.

Abstract: This paper reports on results of interface trap analysis of 3C-SiC MOS capacitors fabricated using four different gate materials and two SiO₂ oxide preparation methods. The results indicate that post-deposition annealing in wet oxygen of PECVD deposited SiO₂ samples increases the near-interface or slow trap densities, compared with wet oxygen thermally oxidized samples. It has also been found that the energy distribution, D_it, of electron states at the oxide/SiC interface of MOS capacitors with different sizes depend on the factor R=P/A, where P stands for the gate perimeter and A for the gate area, which is related to the amount of stress under the edge of the metallic gate.

Abstract: The crystal growth of 3C-SiC onto silicon substrate by Vapour-Liquid-Solid (VLS) transport has been investigated. In the studied growth configuration, propane feeds a SiGe liquid phase contained in 10 µm-deep etched trenches on the Si substrate. Before SiGe deposition, the substrate surface and the trench walls were coated with a thin (100 - 200 nm) CVD-grown 3C-SiC seeding layer. For the VLS growth, the temperature was increased up to 1280°C, above the SiGe alloy melting point, at which point propane was added to start VLS growth. X-ray diffraction shows that some SiC is grown epitaxially onto the CVD seeding layer. However, cross-section SEM observations have evidenced that SiC has grown as trapezoidal islands and not as an uniform layer. Backscattered electron images also clearly show a deep penetration of germanium into the substrate through the SiC seeding layer. This penetration was found to be strongly reduced when increasing the seeding layer thickness from 100 to 200 nm.