1. Department of Materials Science and Engineering and Inter‐University Semiconductor Research Center Seoul National University Seoul 08826 Republic of Korea
2. Electronic Materials Research Center Korea Institute of Science and Technology Seoul 02792 Republic of Korea
3. Key Laboratory of Polar Materials and Devices Department of Electronics East China Normal University Shanghai 200241 China
4. SK Hynix Inc. Icheon Gyeonggi 17336 Republic of Korea
5. Components Research Intel Corporation Hillsboro OR 97124 USA
6. Division of Advanced Materials Engineering Jeonbuk National University Jeonju Jeonbuk 54896 Republic of Korea