Growth Characteristics of CVD Beta‐Silicon Carbide

Abstract

The films of B-SiC were prepared from the methyltrichlorosilane (MTS) by low pressure chemical vapor deposition onto the graphite substrates. The results revealed that the growth rate of ~-SiC increased with the MTS flux; besides, the growth rate increased to a maximum and then decreased with increasing deposition temperature. The preferred orientation of the films was examined by x-ray diffraction, and was found to exhibit a (220) texture in the films of high growth rate and/or long deposition time. The structural morphology was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Observed features indicated the twin plane reentrant edge (TPRE) mechanism as responsible for the B-SiC growth. The growth features of particulate crystals (e.g., dendrites, whiskers, needles) were identified, and also could be interpreted in terms of the TPRE mechanism.Silicon carbide (SIC) is a refractory compound with much promise for certain electronic, optical, and structural applications. Its wide energy bandgap and high saturated drift velocityshould make it a useful high temperature semiconductor. By virtue of its intrinsic oxidation, corrosion and creep resistance at high temperature, as well as its high thermal conductivity, extreme hardness, low neutron absorption cross section, and excellent resistance to chemical attack and thermal shock, SiC is of considerable interest in several fields of science and technology connected with the production or transformation of energy. Additionally, SiC is an excellent infrared transmitting material because it has a cutoff in the IR beyond 5.5 ~m (1-3). The cubic form of B-SiC has a forbidden energy gap of 2.3 eV. This poly-type is also relatively easy to grow at relatively low temperatures via solution or vapor phase deposition routes.B-SiC crystals have been grown by many investigators using chemical vapor deposition (CVD) (4-6) 9 In these papers, methyltrichlorosilane (MTS) was most frequently used, because it has a 1:1 molar ratio of silicon to carbon which results in the deposition of a dense stoichiometric SiC deposit. Essentially, all the studies were concerned with the growth or characterization of SiC. Additionally, the microstructure and the growth mechanism of deposits have also been discussed by several investigators (6-8). The growth mechanism determines the nature of defects and the form of the particulate crystals (e.g., dendrite, whisker, needle), both of which are of prime importance in all applications. The particulate crystal growth, especially in the CVD process, is even more evident as the growth time increases. So, a better understanding of the growth mechanism may aid in improving the quality of crystal and obtaining a larger size crystal.In this paper, crystals of ~-SiC were chemically vapor deposited on graphite substrates by thermal decomposition of CH3SiC13 carried in a flowing hydrogen. An important objective of this study was to characterize the growth mechanism of the R-SiC by investigating the microstructure of the...

Experimental study of atmospheric pressure chemical vapor deposition of silicon carbide from methyltrichlorosilane

“…47,50 On the basis of the results we presented in the preceding section, it is believed that the principal reason for the decrease of the activation energy at temperatures >1473 K and the appearance of negative activation energies for deposition locations far from the entrance of the reactor is the depletion of the gaseous mixture from reactant species and the concomitant decrease of the concentrations of deposition precursors and increase of concentration of deposition products (mainly hydrogen chloride). A similar conclusion was reached in our experiments at subatmospheric pressure.…”

Laser chemical vapor deposition of SiC films with CO2 laser

“…Moreover, by-products of Cl-containing species, mainly HCl, are corrosive, and therefore the inside of the CVD chamber and exhaust gas line should be carefully designed to prevent corrosion. Low pressure CVD (LPCVD) [8][9][10][11][12][13] and plasma-enhanced CVD (PECVD) [14] using metalorganic compounds containing Si are possibly available to avoid explosion and corrosion; however, the deposition rate of SiC films, less than several 10 m h −1 , is too low to obtain a thick coating. Laser-assisted CVD has been conducted to prepare SiC films, but the deposition rate as with those of LPCVD and PECVD, is still too low.…”

Sandwich-structured C/C-SiC composites fabricated by electromagnetic-coupling chemical vapor infiltration

“…However, the outer part far from the fibers shows a dendritic feature, indicating a rapid crystal growth (Fig. 4a) 20–22 . Examination of the innermost layer marked by area 1 reveals the growth to commence with an amorphous SiC layer evidenced by the HRTEM image without crystalline structure and the SAED pattern without obvious diffraction rings (Fig.…”