Issue 5, 2023

Nanoscale compositional segregation in epitaxial AlScN on Si (111)

Abstract

We report the growth of epitaxial wurtzite AlScN thin films on Si (111) substrates with a wide range of Sc concentrations using ultra-high vacuum reactive sputtering. Sc alloying in AlN enhances piezoelectricity and induces ferroelectricity, and epitaxial thin films facilitate systematic structure-based investigations of this important and emerging class of materials. Two main effects are observed as a function of increasing Sc concentration. First, increasing crystalline disorder is observed together with a structural transition from wurtzite to rocksalt at ∼30 at% Sc. Second, nanoscale compositional segregation consistent with spinodal decomposition occurs at intermediate compositions, before the wurtzite to rocksalt phase boundary is reached. Lamellar features arising from composition fluctuations are correlated with polarization domains in AlScN, suggesting that composition segregation can influence ferroelectric properties. The present results provide a route to the creation of single crystal AlScN films on Si (111), as well as a means for self-assembled composition modulation.

Graphical abstract: Nanoscale compositional segregation in epitaxial AlScN on Si (111)

Article information

Article type
Communication
Submitted
06 Dec. 2022
Accepted
06 Marts 2023
First published
06 Marts 2023

Nanoscale Horiz., 2023,8, 674-684

Author version available

Nanoscale compositional segregation in epitaxial AlScN on Si (111)

X. Zhang, E. A. Stach, W. J. Meng and A. C. Meng, Nanoscale Horiz., 2023, 8, 674 DOI: 10.1039/D2NH00567K

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