Nanocrystalline silicon carbide thin films by fluidised/packed bed chemical vapor deposition using a halogen-free single source

Abstract

Thermal stability, vapor pressure, and binary gaseous diffusion coefficients of organosilanes were studied at temperatures in the range of 309-507 K in ambient pressure. The temperature dependence equilibrium vapor pressure (p e ) T data yielded a straight line, when ln p e was plotted against the reciprocal temperature, leading to a standard enthalpy of sublimation (D s H ) values of 43.3 AE 0.6, 68.2 AE 0.8 and 72.4 AE 0.6 kJ mol À1 for 1,4-bis(trimethylsilyl)butadiyne (TMSBu), 1,4bis(trimethylsilyl)benzene (TMSB), and 1,4-bis[(trimethylsilyl)-ethynyl]benzene (TMSEB) and vaporisation (D v H ) values of 33.9 AE 0.2 kJ mol À1 , 44.3 AE 0.6 kJ mol À1 , 64.5 AE 0.5 kJ mol À1 , 75.8 AE 0.6 kJ mol À1 , and 94.3 AE 0.4 kJ mol À1 for triphenylsilane (TPS), 1,4-bis[(trimethylsilyl)-ethynyl] benzene (TMSEB), triphenylvinylsilane (TPVS), 1,1,2,2-tetraphenyldisilane (TPDS), and 1,2dimethyl-1,1,2,2-tetraphenyldisilane (DMTPDS), respectively. In order to find the enthalpy of formation (D f H ) at the condensed and gaseous state of each molecule at standard temperature, the semi-empirical quantum chemical analysis was carried out. The screened/selected ideal candidate was used to deposit silicon carbide thin films on the carbon black or silicon or zirconia particles in the fluidised/packed bed reactor. The deposits were characterized using X-ray diffraction and scanning electron microscopy methods.

Prospects of chemical vapor grown silicon carbide thin films using halogen-free single sources in nuclear reactor applications: A review

“…Recently, we have successfully demonstrated SiC deposition with the combined approach of FB sublimator and fluidized/packed bed CVD process using solid 1,4-bis(trimethylsilyl)benzene as single source. 33 The FB technique confirmed that the 1,4-bis (trimethylsilyl)benzene vapor of the solid source can be effectively carried with high precursor flux in a consistent and controlled manner for CVD use. The obtained orientations, degrees and size of crystallinity, good uniformity, and better thickness with growth rate of the SiC film reveal that SCHEME 4.…”

“…The representative microstructure of the FB SiC material is summarized elsewhere. 33 Scheme 1 shows the microstructure of multiple coatings on a UO 2 kernel fabricated using the FB CVD process. The lowdensity buffer layer of PyC is obtained by the decomposition of acetylene (C 2 H 2 ) at temperatures ranging from 1573 to 1673 K with the density controlled by the gas concentration and temperature.…”

An improved design of TRISO particle with porous SiC inner layer by fluidized bed-chemical vapor deposition

“…Furthermore, we proposed another method to prepare porous SiC coating layer by using nonchloric reactant. There were also some halogen-free precursors for preparing SiC material, such as SiC films [21] and SiC layers [22], using chemical vapor deposition method. In this work, HMDS was used to prepare the porous SiC layer instead of MTS, which is called HMDS method.…”

A novel carbon rich crystalline (C) SiC–Si(n) interface using liquid polycarbosilane as a precursor – a unique Schottky junction

“…Using a single source precursor offers the advantages of having a less complicated CVD system and working at low deposition temperatures. 16 These SiC coated Si wafers behave as a junction due to large difference in band-gap between Si and SiC. The I-V characteristics show a high reverse breakdown voltage and a low cutin voltage.…”