Threading Screw Dislocation-Initiated Step-Flow Growth of 3C-SiC on 4H-SiC

Epitaxial growth of 3C silicon carbide (3C-SiC) layers holds high expectations to tackle the electron mobility challenges of high-power devices based on 4H-SiC. In this work, high-quality polycrystalline 3C-SiC layers are deposited on 4H-SiC substrates by the threading screw dislocation (TSD)-initiated step-flow growth. By optimizing the H2 etching before epitaxy, regular steps are first created on the surface of 4H-SiC substrates to facilitate the step-flow growth of 3C-SiC. The deposition of 3C-SiC is initiated by TSDs in the center of the substrate. Single-TSD and double-TSD initiated step-flow growth are found under the deposition pressures of 100 and 200 mbar, respectively. The step-flow growth mode deteriorates from the center to the edge of 3C-SiC on 4H-SiC wafers because the lowering temperature slows down the diffusion of reactive species in the terrace, which aggravates the island growth. The 4H-SiC buffer layer is then deposited on the surface of the 4H-SiC substrate to stabilize the step-flow growth and improve the crystalline quality of 3C-SiC. We find that the insertion of the 4H-SiC buffer layer creates regularly arranged surface steps throughout the wafer, which promotes the wafer-scale step-flow deposition of 3C-SiC. The resulting 3C-SiC layer exhibits large flat mesas, with an average size of mesa being 170 × 170 μm2. The large mesa significantly reduces the density of grain boundaries and improves the electron mobility of polycrystalline 3C-SiC. The electron mobility of the polycrystalline 3C-SiC in this work is comparable to that of single-crystalline 3C-SiC, which opens up a pathway for expanding the application of 4H-SiC in high-performance metal-oxide-semiconductor field-effect transistors and high-frequency electronics.