**Figure 1.**

*Raman spectra of (a) bare Si(111) substrate, (b) as grown SiC on Si(111), 80 keV argon-sputtered SiC surfaces for fluence of (c) 5 × 1017 Ar+ cm−2 and (d) 7 × 1017 Ar+ cm−2. TA-transverse acoustical, TO-transverse optical, LA-longitudinal acoustical, and LO-longitudinal optical.*

broad distribution of these LO and TO phonon modes, we can assume that the lattice of 3C-SiC is amorphous in nature.

Additionally, Raman spectrum (**Figure 1(b)**) shows prominent Si peak at 520 cm−1 as observed in Si sample. The peak is detected due to the extended depth of the 532 nm laser light in 3C-SiC. In principle, the penetration depth of a given laser in material depends on the incident wavelength used in Raman measurements. The efficient penetration depth of Ar+ ion laser having wavelength of 532 nm in 3C-SiC is larger than 83 μm, and its penetration depth in Si is about 0.935 μm [1–8]. Hence, our as-deposited 3C-SiC films of thickness 0.28 μm appear transparent. Thus, the penetrating light is absorbed within about 0.935 μm of the Si substrate, not in the 0.28 μm thick 3C-SiC, whose phonon intensity is much smaller than that of silicon.

Interestingly, selection rule for the (111) surface of a zinc blende crystal allows both LO and TO phonon mode. In our case, the broadband seen in the range 900–1010 cm−1, which we have devoted to LO vibrations of Si-C bonds in SiC is also associated with Si second-order, that is, 2TO Raman scattering [4–12]. As we have already discussed the penetration depth of the 532 nm laser is more than the thicknesses of 3C-SiC films, so, here, LO phonon peak of SiC layer peak is overlapped with the second order Raman spectrum of silicon as evidenced from **Figure 1(b)**. Interestingly, one can observe small humps on both sides of the LO band. These shoulders are attributed to 2TO peak spreading in the wavenumber region of 920–1050 cm−1. This, in turn, complicates the use of LO peak position for drawing the conclusion on SiC structure.

**Figure 1(c** and **d)** reveals that sputtered SiC surfaces have undergone a substantial change indicative of structural rearrangement. The argon beam interaction has produced severe structural modifications in the surface layers of irradiated specimens. These spectra present three main broad peaks in the 100–550, 550–1100, and 1100–1700 cm−1 spectral region corresponding to Si-Si, Si-C, and C-C bonding, respectively.

Similar to as-deposited sample, Raman spectrum in **Figure 1(c** and **d)** also display sharp 1TO peak at 520 cm−1 characteristic of predominant crystalline structure of the Si substrate. This is due to the large penetration depth of the 532 nm light in 3C-SiC.

Additionally, Raman spectra display the presence of longitudinal phonon mode of Si-C bonds in SiC at wavenumber of 972 cm−1, which is being overlapped with Si-Si bonding 2TO peak.

To qualitatively asses the structure of 3C-SiC, we have further studied in details the contribution from C-C bonds in as-deposited and 80 keV argon-sputtered SiC thin films. For this, we have deconvoluted the region from 1100 to 1700 cm−1 of the Raman spectrum of **Figure 1(b, c** and **d)**. The deconvoluted Raman spectra of SiC thin films within 1100–1700 cm−1 are shown in **Figure 2**.

**Figure 2** depicts that after Gaussian fitting of the Raman spectra, splitting into two peaks has been seen. One typical peak of amorphous carbon (a-C) centered at 1582 cm−1 characteristic of G peak has been observed [13]. The G peak is the result of hybrid C-C bond diffusion of symmetrical stretching vibrating graphite sp2 carbon [6–8]. Interestingly, one a-C peak at 1463 cm−1 also appears. The presence of this peak is attributed to the amorphous carbon content in the sample. Further, this peak presents the incomplete crystallization of carbon clusters [7–19]. Zhang et al. [15] reported the presence of these amorphous carbon bands and ascribed to the mixed sp2 and sp3 C-C bonds in amorphous SiC.

**Figure 2(b** and **c)** depicts that after Gaussian fitting of the Raman spectra, splitting into three peaks has been seen for SiC films following argon ion bombardment at oblique incidence of 500 for fluences of 5 × 1017 Ar+ cm−2, 7 × 1017 Ar+ cm−2. Two typical *Oblique Ar+ Sputtered SiC Thin Films: Structural, Optical, and Electrical Properties DOI: http://dx.doi.org/10.5772/intechopen.112928*
