TY  - JOUR
AU  - Bernstein, Nate S. P.
AU  - Drury, Daniel
AU  - Lee, Cheng-Wei
AU  - Shimada, Tatau
AU  - Sakai, Yuki
AU  - Rehm, Oliver
AU  - Baumgarten, Lutz
AU  - Mueller, Martina
AU  - Gorai, Prashun
AU  - Iwazaki, Yoshiki
AU  - Fox, Glen R.
AU  - Yazawa, Keisuke
AU  - Hanrahan, Brendan
AU  - Brennecka, Geoff L.
TI  - Ferroelectricity of wurtzite Al<sub>1−x</sub>Hf<sub>x</sub>N heterovalent alloys
JO  - Applied physics letters
VL  - 127
IS  - 6
SN  - 0003-6951
CY  - Melville, NY
PB  - American Inst. of Physics
M1  - PUBDB-2025-04445
SP  - 062902
PY  - 2025
AB  - Thin films of aluminum hafnium nitride (Al<sub>1−x</sub>Hf<sub>x</sub>N) were synthesized via reactive magnetron sputtering for Hf contents up to x = 0.13. X-ray diffraction showed a single c-axis oriented wurtzite phase for all films. Hard x-ray photoelectron spectroscopy demonstrated homogeneous Al:Hf distribution through the thin films and confirmed their insulating character. A collection of complementary tests showed unambiguous polarization inversion, and thus ferroelectricity in multiple samples. Current density vs electric field hysteresis measurements showed distinct ferroelectric switching current peaks, the piezoelectric coefficient <sub>d33,f,meas</sub> measured using a double beam laser interferometer (DBLI) showed a reversal in sign with similar magnitude, and anisotropic wet etching confirmed field-induced polarization inversion. This demonstrates the possibility of using tetravalent–and not just trivalent–alloying elements to enable ferroelectricity in AlN-based thin films, highlighting the compositional flexibility of ferroelectricity in wurtzites and greatly expanding the chemistries that can be considered for future devices.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1063/5.0271563
UR  - https://bib-pubdb1.desy.de/record/639344
ER  -