Issue 44, 2021

Epitaxial growth of β-Ga2O3 (−201) thin film on four-fold symmetry CeO2 (001) substrate for heterogeneous integrations

Abstract

β-Ga2O3 is a wide bandgap semiconductor material that is promising for many fields such as gas sensors, UV detectors, and high-power electronics. Until now, most epitaxial β-Ga2O3 thin films could only be realized on six-fold symmetric single crystal substrates including sapphire (0001), 3C-SiC (001), and native β-Ga2O3. In this report, we demonstrate the epitaxial growth of β-Ga2O3 (−201) thin films on non-six-fold symmetric substrates, i.e., the CeO2 (001) substrate. Different from the conventional six-fold symmetric sapphire substrates, the four-fold symmetric cubic phase CeO2 (001) induces the formation of two sets of hexagonal-like atom frameworks with a mutual rotation angle of 90° in the β-Ga2O3 (−201) plane. This is due to the small lattice mismatch between the β-Ga2O3 (−201) plane and the CeO2 (001) plane in two directions: CeO2 [100]//β-Ga2O3 [010] and CeO2 [010]//β-Ga2O3 [010]. Besides, the valence band offset (VBO) and the conduction band offset (CBO) at the β-Ga2O3/CeO2 heterojunction are examined using high-resolution X-ray photoelectron spectroscopy (HR-XPS) and are estimated to be 1.63 eV and 0.18 eV, respectively, suggesting a type-II heterostructure. The obtained epitaxial β-Ga2O3 thin films are fabricated into photodetectors (PDs), which show key photoelectrical characteristics that are similar to those of PDs using the conventional sapphire substrate. The results indicate the epitaxial β-Ga2O3 thin films on CeO2 have a high crystallization quality, and thus are capable of producing various essential devices. Moreover, the epitaxy between β-Ga2O3 (−201) and CeO2 (001) demonstrated in this work can pave the way for constructing heterostructures between β-Ga2O3 and other cubic-phase functional materials, such as p-type semiconductors, piezoelectric semiconductors, and superconductors.

Graphical abstract: Epitaxial growth of β-Ga2O3 (−201) thin film on four-fold symmetry CeO2 (001) substrate for heterogeneous integrations

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
19 Kho 2021
Accepted
19 Ndz 2021
First published
20 Ndz 2021

J. Mater. Chem. C, 2021,9, 15868-15876

Epitaxial growth of β-Ga2O3 (−201) thin film on four-fold symmetry CeO2 (001) substrate for heterogeneous integrations

X. Tang, K. Li, C. Liao, D. Zheng, C. Liu, R. Lin, N. Xiao, S. Krishna, J. Tauboada and X. Li, J. Mater. Chem. C, 2021, 9, 15868 DOI: 10.1039/D1TC02852A

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