Fig. 1: Characterization and first-principles study of ScAlN.
From: Unveiling the Pockels coefficient of ferroelectric nitride ScAlN
a 32-atom unit cell of wurtzite ScAlN with a Sc concentration of 12.5%. b Cross-sectional SEM imaging of 600 nm-thick Sc0.3Al0.7N, presenting the poly-crystalline nature of sputter-deposited ScAlN thin films. c XPS analysis of ScAlN films and the reference poly-AlN sample, yielding an analytical Sc concentration of 12.6 ± 1.2% and 31.9 ± 3.2% for the two Sc-alloyed samples. d Out-of-plane XRD containing characteristic peaks for ScAlN, Si, and Mo. Inset: Rocking curve measurement showing FWHMs ≤ 1.6° for both ScAlN samples. AlN sample sputtered on insulator substrate exhibits a larger 2.6° FWHM. e Comparison between measured (Exp.) and DFT-calculated lattice parameters at various Sc concentrations. f Calculated Pockels coefficients r13, r33, and r51. Notably, r33 has the potential to exceed that of LN at high levels of Sc alloying. A log/linear scale is adopted for the y-axis, marked by purple and blue background colors, respectively.
