On-device cryogenic quenching enables robust amorphous tellurium for threshold switching

Article https://doi.org/10.1038/s41467-025-68223-0 On-device cryogenic quenching enables robust amorphous tellurium for threshold switching Received: 7 July 2025 Check for updates 1234567890():,; 1234567890():,; Accepted: 22 December 2025 Namwook Hur 1, Seunghwan Kim2, Yu Bin Park Sohui Yoon1, Youngseok Cho2, Tae Hoon Lee 3 3 , Changhwan Kim1, & Joonki Suh 2 Amorphous chalcogenide alloys exhibiting crystallization-free Ovonic threshold switching behaviour have gained immense attention as selector materials. While the switching characteristics depend on the chalcogen species, understanding device-level elemental behaviour, particularly for tellurium (Te), remains challenging due to its low crystallization temperature and poor glass-forming ability. Here, we realize an electrothermally induced amorphous Te (a-Te) phase via on-device cryogenic quenching, which rapidly suppresses crystallization in the supercooled liquid at low ambient temperature. The order-to-disorder transition yields a ~ 0.81 V increase in threshold voltage and a ~ 10³ reduction in subthreshold current, attributed to enhanced deep-level trap formation. The a-Te phase exhibits reliable self-regulated oscillations, driven by deep traps, distinguishing it from conventional capacitance-driven effects. These findings support that the threshold switching in Te originates from defect-mediated transitions occurring before melting, rather than solely from thermal phase-change effects. Our results provide insights into chalcogenide switching mechanisms and pave the way for stoichiometry-tuned selector devices, nano-oscillators, and selector-only memory applications. Ovonic threshold switching (OTS), a volatile electronic switching phenomenon observed in amorphous chalcogenide alloys, has generated intense interest as a crucial enabler for high-speed, energyefficient memory and logic systems when integrated as a selector element1. OTS behavior is marked by a rapid, substantial current increase, often spanning several orders of magnitude, at a specific threshold voltage (Vth) without inducing crystallization2,3, thus retaining the amorphous structure over 106–108 operation cycles. These characteristics position amorphous chalcogenides as ideal candidates for selector devices in high-density, parallel-processing memory arrays, where precise write and read operations are paramount4,5. Over the past decades, extensive material-level design approaches, including doping6–8 and heterogeneous structuring9–11, have been explored to enhance the selector performances. More recently, unconventional behaviors such as the prior pulse polarity effect12,13 and self-regulating oscillation14,15 have been observed, highlighting the significant impact of chalcogen species selection: tellurium (Te) vs. selenium (Se). Unlike Se-based systems, Te-containing alloys typically exhibit smaller bandgaps, lower glass transition temperatures, and a higher density of shallow trap states. More specifically, Te becomes stabilized in the amorphous matrix through enhanced covalency with other elements, thereby enabling unipolar switching and reliable oscillation. However, even though the primary component is attributed to a threshold characteristic, the intrinsic contribution of the amorphous chalcogen itself has not been directly investigated. 1 Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea. 2Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea. 3School of Materials Science and e-mail: ; Engineering, Kyungpook National University, Daegu, Republic of Korea. Nature Communications | (2026)17:1509 1 Article In parallel, elemental Te itself has been intensively investigated across a broad spectrum of fields, from fundamental materials science to practical device applications. Te forms a quasi-two-dimensional atomic configuration, consisting of one-dimensional helical chains held together by van der Waals (vdW) interactions16,17. Highly crystalline Te (c-Te) films are typically produced via traditional physical vapor deposition methods18–20 and, very recently, by atomic layer deposition (ALD)21. Owing to their intrinsic p-type semiconducting behavior21–24, Te has enabled the development of diverse complementary logic devices21,25,26. In addition, Te has emerged as a potential selector component, exhibiting a first-order crystal-liquid phase transition through local Joule heating20,27. The high Schottky barrier between Te and TiN enables threshold switching with low and high current operation in the crystalline solid and metallic-like liquid states. Despite growing interest, prior studies have predominantly focused on highly c-Te. In contrast, the solid-state amorphous counterpart of Te remains unexplored, largely due to its low crystallization temperature (Tcry) of −10–0 °C18 and poor glass-forming ability. While several attempts have been made to stabilize amorphous Te (a-Te) and characterize its physical properties, these efforts have been limited to a closed cryogenic deposition system, not yet extended to functional electronic device integration28–31. Meanwhile, computational investigations of monatomic amorphous chalcogen matrix have suggested hypervalent bonding networks in a-Te, distinct from conventional covalent bonding in Se- or S-based amorphous matrices32–35, further motivating experimental verification of its electronic properties. In this work, we demonstrate a robust approach for stabilizing an electronic device that integrates both the ordered and disordered solid states of Te by simultaneously controlling the internal and external thermal conditions. The nanoscale chalcogen-metal contact effectively induced Joule heating within the proposed via-hole device, enabling selective phase transitions from the liquid chalcogen. Specifically, the rapid electrothermal quenching resulted in a disordered configuration by suppressing crystallization kinetics, sustaining its atomic arrangement under a cryogenic environment. The degradation of crystallinity generated thermally stable deep-level traps within the Te layer, resulting in a higher Vth, lower conductance, and reliable oscillation behavior. Furthermore, the formation of a highly oriented single-domain structure, thermodynamically grown from amorphous nuclei, distinctly contrasts with the polycrystalline morphology induced by electrical pulses, thereby providing indirect evidence of amorphization within the device. Although sputtered Te devices have previously been reported to show volatile switching behavior20,27, we now clarify that this behavior is governed by defect-driven switching that occurs prior to the solid-liquid transition. Furthermore, on-device cryogenic stabilization of both c- and a-Te allows us to resolve distinct physical and electrical features, most notably a self-regulating oscillation in a-Te that (...truncated)