A Study of 6H-Seeded 4H-SiC Bulk Growth by PVT

Tupitsyn, Eugene Y.; Arjunan, Arul Chakkaravarthi; Bondokov, Robert T.; Kennedy, Robert M.; Sudarshan, Tangali S.

doi:10.4028/0-87849-963-6.21

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“…3−6 In particular, 4H-SiC is the preferred polytype in most of the main applications of SiC-based devices due to its wide band gap and high electron mobility. 7 Crystallographic polarity generally has a large influence on the physical and chemical properties of the surfaces and interfaces of heterostructures due to the different chemical nature of the terminating atoms. SiC is a typically polar semiconductor with different terminating atoms on each surface; that is, it presents "silicon (Si) faces" and "carbon (C) faces.…”

Section: ■ Introductionmentioning

confidence: 99%

Using Visible Laser-Based Raman Spectroscopy to Identify the Surface Polarity of Silicon Carbide

et al. 2016

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In this study we developed an approach to identify the surface polarity of silicon carbide (SiC) by using an excitation laser possessing a photon energy (2.33 eV) much lower than the band gap of . By gradually attenuating the intensity of the excitation laser, the effective depth that the laser could generate Raman signals could eventually be limited to within the ultrashallow region of the SiC wafer. Through three-dimensional finite-difference-timedomain (3D-FDTD) simulations, we found that the depth of the high electric field region could be limited from several micrometers below the surface to the near-surface region of 4H-SiC, merely by attenuating the power of the incident laser. Experimentally, we observed a clear trend in the Raman peak intensity ratio of the signals at 210 and 203 cm −1 in the FTA mode: the intensity ratio of the Si face was always higher than that of the C face regardless of the measurement position on the 4H-SiC wafer. Even through the carrier concentrations in the 4H-SiC wafer were nonuniform, the resulting variability in peak intensity did not influence the trend in the intensity ratio, which could, therefore, be used to identify the surface polarity. This approach might also allow characterization of different polytypes of SiC, for example, 6H-SiC and 3C-SiC, the optical band gaps of which are lower than that of 4H-SiC. Because this optical approach using low-photon-energy laser-based Raman spectroscopy is nondestructive, simple, and rapid and employs excitation light of low photon energy, it should be very applicable for characterizing the surface properties of various other crystalline materials.

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Section: ■ Introductionmentioning

confidence: 99%