Enhanced nitrogen incorporation in the 〈112̄0〉 directions on the (0001̄) facet of 4H-SiC crystals

Abstract

Enhanced nitrogen doping in the <11−20> directions on the (000−1) facet of 4H-SiC crystals grown by the physical vapor transport (PVT) growth method was investigated using Raman scattering microscopy and atomic force microscopy (AFM). The enhanced nitrogen doping showed either single or double peak structure of nitrogen incorporation in the azimuthal direction around <11−20>. AFM observations revealed that these two characteristic doping structures stemmed from different propagation morphologies of spiral steps on the (000−1) facet. It was also unveiled that the change in the step-flow direction was always associated with the change of the terrace-width ratio on the facet, and that the interplay between these two parameters determined the nitrogen incorporation on the (000−1) facet. On the basis of these experimental results, the mechanism of the azimuthal dependence of nitrogen incorporation on the (000−1) facet during PVT growth of 4H-SiC crystals is discussed.

Role of the Growth Facet on the Generation and Expansion of Stacking Faults in PVT-Grown n-Type 4H-SiC Single-Crystal Boules

“…In order to verify the stress distribution across the facet and nonfacet regions, we plot the FTO-peak mapping of the region in Figure (b). As shown in Figure (d), the interface between the facet and nonfacet regions of n -type 4H-SiC has prominent higher wavenumbers because of the differences of N concentration and growth velocity between the facet and nonfacet region . In addition, the FTO-peak positions of SFs (3,3) tending to abruptly shift toward higher wavenumbers always occurs, implying that the compressive strain exists in SFs (3,3). , This indicates that the shear stress exerted in the nonfacet region is released by the formation and expansion of SFs (3,3), due to the low formation energies of SFs in n -type 4H-SiC.…”

“…The intensities of the FTA mode and FTO mode of the SF region are lower than those of the SF-free region, indicating structural distortions in the SF region. Because the growth-facet region has a higher N concentration , and thus a higher free-electron concentration, the peak position of FLO in the facet region should shift to higher wavenumbers . Therefore, the FLO-peak mapping is used to investigate the distribution of SFs along the growth facet of the vertically sliced n -type 4H-SiC sample.…”

Advances and challenges in 4H silicon carbide: defects and impurities

“…Traditionally, intentional doping has been employed to introduce impurities and modulate the conductivity of 4H-SiC [26,27]. For instance, p-type semiconductors can be obtained by doping with aluminum, boron, or gallium, while the introduction of impurities such as nitrogen and phosphorus result in n-type semiconductors [28][29][30]. However, inadvertently introduced impurities typically have adverse effects on the properties of 4H-SiC, leading to a degradation in the reliability and performance of semiconductor devices.…”