Atomic-layer deposition of crystalline BeO on SiC

For the first time, an epitaxial beryllium oxide (BeO) film was grown on 4H silicon carbide (4H-SiC) by atomic layer deposition (ALD) at a low temperature of 250 °C. The BeO film had a large lattice mismatch with the substrate (>7–8%), but it was successfully grown to a single crystal by domain-matching epitaxy (DME). The bandgap energy, dielectric constant, and thermal conductivity properties of crystalline BeO are suitable for power transistors that require low leakage currents and fast heat dissipation in high electric fields. Physical characterization confirmed the single-crystalline BeO (0 0 2). Raman analysis showed that the E ₁ and A ₁ phonon modes of ALD BeO were intermixed with the E ₂ and A ₁ phonon modes of SiC, resulting in a significant increase in phonon intensity. After heat treatment at a high temperature, a small amount of SiO ₂ interfacial oxide was formed but the stoichiometry of BeO was maintained. From the capacitance-voltage (C-V) curves, we obtained a dielectric constant of 6.9 and calculated a low interface trap density of 6 × 10 ¹⁰ cm ⁻² ·eV ⁻¹ using the Terman method at E _c -E _t = 0.6 eV. The high bandgap, thermal conductivity, and excellent crystallinity reduced the dangling bonds at the interface of BeO-on-SiC.