Effects of excess carbon and vibrational properties in ultrafine SiC powders

Amorphous to crystalline phase transition in pulsed laser deposited silicon carbide

“…In addition, all spectra show a small dip at 967 cm À1 corresponding to the transparent longitudinal optical (LO) phonon mode, though it is most evident for the film grown at 950 8C. The occurrence of this dip is related to the Berreman effect [49] and has been also observed for crystalline SiC films [32,42] as well as small particles and ultra-fine powders of SiC [35,50]. However, close inspection of the FTIR spectra may indicate a double peak structure that could due to the presence of amorphous and crystalline phases of SiC in the layers [51], but their respective contributions to the FTIR signal are clearly unresolved and may thus difficult to quantify in a meaningful manner.…”

Diverse Role of Silicon Carbide in the Domain of Nanomaterials

“…The band gap of Si at room temperature is 1.12 eV whereas diverse for SiC because it exists in over 200 crystalline forms and among them the most common types are 3C, 6H, and 4H, which have band gaps of 2.2, 3.02, and 3.20 eV, respectively [1]. Silicon carbide is a promising material due to its unique ability to adopt different crystalline polytypes which monitor the band gap and then the electronic and optical properties [2][3][4]. Despite being an indirect band gap semiconductor, SiC is used in several high-performance electronic and optical devices due to its unique physical and electronic properties.…”

Band Structure of Non-Steiochiometric Large-Sized Nanocrystallites

“…The SiC large-sized nanopowders were synthesized by a CO 2 laser pyrolysis of silane and acetylene gaseous mixtures following a technical device described in [2].…”

“…The TEM data show that nearthe-interface layers have thickness changing from 2 to 4 nm. The EPR, X-ray and other structural investigations [2] have shown that the near-the-interface levels play a key role in the electronic properties of the SiC NC. It is also seen from the above mentioned figures that one chosen segment of the interface (squared in figure 4) is responsible for electronic properties of the whole composite.…”

“…Recently, there appeared a new direction in the nano-technology consisting in the possibility of using the nanocrystallites as materials for optics and electronics due to the size-dependent electronic and optical properties of these materials [1][2][3][4][5][6][7][8].…”