On the exceptional temperature stability of ferroelectric AlScN thin films
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arXiv
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2021
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| author | Islam, MD Redwanul Wolff, Niklas Yassine, Mohammed Schönweger, Georg Christian, Björn Kohlstedt, Hermann Ambacher, Oliver Lofink, Fabian Kienle, Lorenz Fichtner, Simon |
| author_facet | Islam, MD Redwanul Wolff, Niklas Yassine, Mohammed Schönweger, Georg Christian, Björn Kohlstedt, Hermann Ambacher, Oliver Lofink, Fabian Kienle, Lorenz Fichtner, Simon |
| contents | Through its dependence on low symmetry crystal phases, ferroelectricity is inherently a property tied to the lower temperature ranges of the phase diagram for a given material. This paper presents conclusive evidence that in the case of ferroelectric AlScN, low temperature has to be seen as a purely relative term, since its ferroelectric-to-paraelectric transition temperature is confirmed to surpass 1100°C and thus the transition temperature of virtually any other thin film ferroelectric. We arrived at this conclusion through investigating the structural stability of 0.4 - 2 $μ$m thick Al$_{0.73}$Sc$_{0.27}$N films grown on Mo bottom electrodes via in situ high-temperature X-ray diffraction and permittivity measurements. Our studies reveal the wurtzite-type structure of Al$_{0.73}$Sc$_{0.27}$N is conserved during the entire 1100°C annealing cycle, apparent through a constant c over a lattice parameter ratio. In situ permittivity measurements performed up to 1000°C strongly support this conclusion and include what could be the onset of a diverging permittivity only at the very upper end of the measurement interval. Our in situ measurements are well-supported by ex situ (scanning) transmission electron microscopy and polarization and capacity hysteresis measurements. These results confirm the structural stability on the sub-$μ$m scale next to the stability of the inscribed polarization during the complete 1100°C annealing treatment. Thus, AlScN is the first readily available thin film ferroelectric with a temperature stability that surpasses virtually all thermal budgets occurring in microtechnology, be it during fabrication or the lifetime of a device - even in harshest environments. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2105_08331 |
| institution | arXiv |
| publishDate | 2021 |
| record_format | arxiv |
| spellingShingle | On the exceptional temperature stability of ferroelectric AlScN thin films Islam, MD Redwanul Wolff, Niklas Yassine, Mohammed Schönweger, Georg Christian, Björn Kohlstedt, Hermann Ambacher, Oliver Lofink, Fabian Kienle, Lorenz Fichtner, Simon Materials Science Through its dependence on low symmetry crystal phases, ferroelectricity is inherently a property tied to the lower temperature ranges of the phase diagram for a given material. This paper presents conclusive evidence that in the case of ferroelectric AlScN, low temperature has to be seen as a purely relative term, since its ferroelectric-to-paraelectric transition temperature is confirmed to surpass 1100°C and thus the transition temperature of virtually any other thin film ferroelectric. We arrived at this conclusion through investigating the structural stability of 0.4 - 2 $μ$m thick Al$_{0.73}$Sc$_{0.27}$N films grown on Mo bottom electrodes via in situ high-temperature X-ray diffraction and permittivity measurements. Our studies reveal the wurtzite-type structure of Al$_{0.73}$Sc$_{0.27}$N is conserved during the entire 1100°C annealing cycle, apparent through a constant c over a lattice parameter ratio. In situ permittivity measurements performed up to 1000°C strongly support this conclusion and include what could be the onset of a diverging permittivity only at the very upper end of the measurement interval. Our in situ measurements are well-supported by ex situ (scanning) transmission electron microscopy and polarization and capacity hysteresis measurements. These results confirm the structural stability on the sub-$μ$m scale next to the stability of the inscribed polarization during the complete 1100°C annealing treatment. Thus, AlScN is the first readily available thin film ferroelectric with a temperature stability that surpasses virtually all thermal budgets occurring in microtechnology, be it during fabrication or the lifetime of a device - even in harshest environments. |
| title | On the exceptional temperature stability of ferroelectric AlScN thin films |
| topic | Materials Science |
| url | https://arxiv.org/abs/2105.08331 |