Anisotropic dielectric functions, band-to-band transitions, and critical points in α -Ga 2 O 3
- Award ID(s):
- 1808715
- NSF-PAR ID:
- 10222750
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 118
- Issue:
- 6
- ISSN:
- 0003-6951
- Page Range / eLocation ID:
- 062103
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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SiC and Ga 2 O 3 are promising wide band gap semiconductors for applications in power electronics because of their high breakdown electric field and normally off operation. However, lack of a suitable dielectric material that can provide high interfacial quality remains a problem. This can potentially lead to high leakage current and conducting loss. In this work, we present a novel atomic layer deposition process to grow epitaxially Mg x Ca 1− x O dielectric layers on 4H-SiC(0001) and β-Ga 2 O 3 $\left( {\bar 201} \right)$ substrates. By tuning the composition of Mg x Ca 1− x O toward the substrate lattice constant, better interfacial epitaxy can be achieved. The interfacial and epitaxy qualities were investigated and confirmed by cross-sectional transmission electron microscopy and X-ray diffraction studies. Mg 0.72 Ca 0.28 O film showed the highest epitaxy quality on 4H-SiC(0001) because of its closest lattice match with the substrate. Meanwhile, highly textured Mg 0.25 Ca 0.75 O films can be grown on β-Ga 2 O 3 $\left( {\bar 201} \right)$ with a preferred orientation of (111).more » « less