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Title: Dielectric function tensor (1.5 eV to 9.0 eV), anisotropy, and band to band transitions of monoclinic β -(Al x Ga 1– x ) 2 O 3 ( x ≤ 0.21) films
Authors:
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Award ID(s):
1808715
Publication Date:
NSF-PAR ID:
10145686
Journal Name:
Applied Physics Letters
Volume:
114
Issue:
23
Page Range or eLocation-ID:
231901
ISSN:
0003-6951
Sponsoring Org:
National Science Foundation
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  1. 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).