Soret-Effect Induced Phase-Change in a Chromium Nitride Semiconductor Film

Yi Shuang; Shunsuke Mori; Takuya Yamamoto; Shogo Hatayama; Yuta Saito; Paul J Fons; Yun-Heub Song; Jin-Pyo Hong; Daisuke Ando; Yuji Sutou

doi:10.1021/acsnano.4c03574

Soret-Effect Induced Phase-Change in a Chromium Nitride Semiconductor Film

ACS Nano. 2024 Aug 13;18(32):21135-21143. doi: 10.1021/acsnano.4c03574. Epub 2024 Aug 1.

Authors

Yi Shuang¹, Shunsuke Mori², Takuya Yamamoto³, Shogo Hatayama², Yuta Saito⁴, Paul J Fons⁵, Yun-Heub Song⁶, Jin-Pyo Hong⁷, Daisuke Ando², Yuji Sutou^{1

2}

Affiliations

¹ WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan.
² Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6-11 Aoba-yama, Sendai 980-8579, Japan.
³ Department of Metallurgy, Graduate School of Engineering, Tohoku University, Miyagi 980-8579, Japan.
⁴ Device Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, Umezono 1-1-1, Tsukuba 305-8568, Japan.
⁵ Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan.
⁶ Department of Electronic Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea.
⁷ Department of Physics, Hanyang University, Seoul 04763, Korea.

Abstract

Phase-change materials such as Ge-Sb-Te (GST) exhibiting amorphous and crystalline phases can be used for phase-change random-access memory (PCRAM). GST-based PCRAM has been applied as a storage-class memory; however, its relatively low ON/OFF ratio and the large Joule heating energy required for the RESET process (amorphization) significantly limit the storage density. This study proposes a phase-change nitride, CrN, with a much wider programming window (ON/OFF ratio more than 10⁵) and lower RESET energy (one order of magnitude reduction from GST). High-resolution transmission electron microscopy revealed a phase-change from the low-resistance cubic CrN phase into the highly resistive hexagonal CrN₂ phase induced by the Soret-effect. The proposed phase-change nitride could greatly expand the scope of conventional phase-change chalcogenides and offer a strategy for the next-generation of PCRAM, enabling a large ON/OFF ratio (∼10⁵), low switching energy (∼100 pJ), and fast operation (∼30 ns).

Keywords: melting-free; nitride; nonvolatile memory; phase-change materials; soret-effect.