Polytype switching identification in 4H-SiC single crystal grown by PVT

Abstract

Generally, it is very difficult to grow large diameter 4H-SiC single crystal with single polytype by Physical Vapor Transport (PVT) growth method and mostly it ends up with the presence of some other polytypes (viz. 6H, 15R). This paper presents the various comprehensive polytype identification techniques in SiC wafer grown by PVT method. Characterization techniques, viz. X-Ray diffraction, Scanning electron microscopy, Cathodoluminescence (CL) and Raman spectroscopy, are used in the present study in order to identify the presence of 4H, 6H and 15R polytype region in SiC wafer. Raman mapping (using phonon frequencies at 150, 171, 203 cm −1 for 6H, 15R and 4H, respectively) and X-Ray Topography [using grazing incidence asymmetric plane (11-2 8) for 4H-SiC, (11-2 12) for 6H-SiC and (11-2 30) for 15H-SiC] and CL spectra (defect state peak positions at ~ 500 nm and 580 nm for 4H and 6H, respectively) are proposed to distinguish the switching of polytypes in a large area SiC wafer. The polytype switching in SiC ingot may occur because of temperature fluctuations during the sublimation growth process.

Defect-Induced Luminescence Quenching of 4H-SiC Single Crystal Grown by PVT Method through a Control of Incorporated Impurity Concentration

“…Their appearance was due to the double diffraction effect, as explained by other researchers [21]. Herein, for the highly purified 4H-SiC, the small periodic peaks between the main peaks that were related to the double diffraction effect could indicate the polytype of a SiC crystal with small periodic peaks due to the periodic stacking layers in the c-direction on the crystal [21]. For our XRD results, after the purification process (S2 and S3), small periodic peaks were also observed, as shown in Figure 4.…”

“…Furthermore, a few peaks of low intensity that were separated by almost equal intervals were also observed. These weak diffraction peaks were due to the (0005), (0006), and (0007) planes [21]. Their appearance was due to the double diffraction effect, as explained by other researchers [21].…”

“…Figure 4 shows two prominent peaks at 36 • and 76 • , which are the reflections from the (0004) and (0008) planes, which correspond to 4H-SiC [20,21]. In addition, all peaks are good agreement with ICSD card 98-016-4971.…”

“…These weak diffraction peaks were due to the (0005), (0006), and (0007) planes [21]. Their appearance was due to the double diffraction effect, as explained by other researchers [21]. Herein, for the highly purified 4H-SiC, the small periodic peaks between the main peaks that were related to the double diffraction effect could indicate the polytype of a SiC crystal with small periodic peaks due to the periodic stacking layers in the c-direction on the crystal [21].…”

“…These peaks at 35.7°, 41.2°, 59.9°, and 71.6° are attributed to the (111), ( 200), (220), and (311) planes of the β-SiC phase, respectively [18,19]. Figure 4 shows two prominent peaks at 36° and 76°, which are the reflections from the (0004) and (0008) planes, which correspond to 4H-SiC [20,21]. In addition, all peaks are good agreement with ICSD card 98-016-4971.…”