hBN-Layer-Promoted Heteroepitaxy in Reactively Sputter-Deposited MoS x≈2 (0001)/Al 2 O 3 (0001) Thin Films: Implications for Nanoelectronics

Deshpande, Aditya; Hojo, Koki; Tanaka, Koichi; Arias, Pedro; Zaid, Hicham; Liao, Michael; Goorsky, Mark; Kodambaka, Suneel Kumar

doi:10.1021/acsanm.2c05290

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).

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