Shinnosuke Yasuoka1,Kazuki Okamoto:1,Takao Shimizu2,3,Hiroshi Funakubo1
Tokyo Institute of Technology1,National Institute for Materials Science2,Precursory Research for Embryonic Science and Technology3
Shinnosuke Yasuoka1,Kazuki Okamoto:1,Takao Shimizu2,3,Hiroshi Funakubo1
Tokyo Institute of Technology1,National Institute for Materials Science2,Precursory Research for Embryonic Science and Technology3
Ferroelectric wurtzite-(Al,Sc)N is promising for future ferroelectric devices because of its superior properties, including large remanent polarization that is almost 5 times larger than that of HfO<sub>2</sub>-based ferroelectrics. Therefore, (Al,Sc)N film has been investigated by many researchers after the experimental demonstration of its ferroelectricity in 2019 [1-3]. Nevertheless, the investigation of switching kinetics of ferroelectric to elucidate the physical properties of this material has been still limited, although it is essential not only to understand the fundamental properties, but also to promote the development of next-generation ferroelectric devices.<br/>In this study, we investigated the polarization switching kinetics of (Al,Sc)N thin films with different Sc/(Al+Sc)N. The pulse-width dependent polarization switching was conducted and analyzed in term of a phenomenological and macroscopic approach for the (Al<sub>0.9</sub>Sc<sub>0.1</sub>)N, (Al<sub>0.8</sub>Sc<sub>0.2</sub>)N, and (Al<sub>0.7</sub>Sc<sub>0.3</sub>)N films. The switching characteristics obtained by switching test with various pulse width were in good agreement with t the KAI model [4]. The fitting parameter, the Avrami index <i>n</i>, were approximately 2, indicating the bidimensional in-plane propagation of the switched domains as reported for typical oriented ferroelectric thin films [5,6]. The activation field, <i>E</i><sub>a</sub>, which is evaluated from the time dependent current (<i>I</i>-<i>t</i>) curve through the switching time, <i>t</i><sub>sw </sub>based on Merz's law, which is obtained from the current-depended on the film composition. That of (Al<sub>0.8</sub>Sc<sub>0.2</sub>)N was slightly smaller than those of the films with other composition[7]. This may be due to differences in fundamental switching characteristics, which is significantly affected by composition and/or crystal quality.<br/><br/>This work was partly supported by the project of MEXT Initiative to Establish Next-generation Novel Integrated Circuits Centers (X-NICS)( JPJ011438) and MEXT Program: Data Creation and Utilization Type Material Research and Development Project (JPMXP1122683430). This work was also partly supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant No. 21H01617, 22K18307, and 22K20427; and by JST PRESTO Grant Number JPMJPR20B3, Japan.<br/><br/><br/>[1] Fichtner, <i>et al.</i>, J. Appl. Phys., <b>125</b>, 114103 (2019).<br/>[2] Yasuoka <i>et al.</i>, J. Appl. Phys., <b>128</b>, 114103 (2020).<br/>[3] Yasuoka <i>et al</i>., ACS Appl. Electron. Mater., <b>4</b>, 5165 (2022).<br/>[4] Ishibashi, J. Phys. Soc. Japan <b>31</b>, 506 (1971).<br/>[5] Li <i>et al.</i>, <i>Appl. Phys. Lett</i>. <b>86</b>, 1 (2007)<br/>[6] Fichtner et al, <i>Jt. Conf. IEEE (IFCS-ISAF)</i>, <i>Proc.</i>, <b>5</b> (2020)<br/>[7] Merz, <i>Phys. Rev</i>. <b>95</b>, 3 (1954)