Ferroelectric Al1−xBxN sputtered thin films on n-type Si bottom electrodes

Abstract Ferroelectric Al 1− x B x N thin films are grown on highly doped and plasma treated (100) n -type Si. We demonstrate ferroelectricity for x = < 0.01, 0.02, 0.06, 0.08, 0.13, and 0.17 where the n -type Si is both the substrate and bottom electrode. Polarization hysteresis reveals remanent polarization values between 130 and 140 μC/cm 2 and coercive field values as low as 4 MV/cm at 1 Hz with low leakage. The highest resistivity and most saturating hysteresis occurs with B contents between x = 0.06 and 0.13. We also demonstrate the impact of substrate plasma treatment time on Al 1− x B x N crystallinity and switching. Cross-sectional transmission electron microscopy and electron energy loss spectra reveal an amorphous 3.5 nm SiN x layer at the Al 1− x B x N interface post-plasma treatment and deposition. The first ~ 5 nm of Al 1− x B x N is crystallographically defective. Using the n -type Si substrate, we demonstrate Al 1− x B x N thickness scaling to 25 nm via low-frequency hysteresis and CV. Serving as the bottom electrode and substrate, the n -type Si enables a streamlined growth process for Al 1− x B x N for a wide range of Al 1− x B x N compositions and layer thicknesses.