Abstract
The resistive switching of an Ovonic threshold switch (OTS) material is characterized by Poole-Frenkel (PF) conduction and atomic rearrangement originating from chalcogen defects; thus, most OTS materials contain Se and/or Te. In addition to these chalcogen elements, As is included to form rigid amorphous networks. However, since As and Se are toxic, the development of As- and Se-free OTS materials is strongly desired. To realize As-free OTS materials that exhibit a comparable or even superior performance, a new strategy for material development should be established. In this study, we aimed to add Te to a HfO2 insulator to convert the electric conduction mechanism to PF conduction for realizing a selector function. The optical and electrical characteristics of Hf–O–Te ternary amorphous films with various Te contents were investigated. By changing the Te content, the optical bandgap was found to be tuned in the range of 0.46–5 eV, concomitantly with the modification of electrical properties. The electrical characteristics of the films demonstrated a strong compositional dependence, and Hf0.24O0.55Te0.21 was found to exhibit PF conduction, resulting in a selector function with a selectivity of approximately two orders of magnitude. These results indicate that the inclusion of a heavy chalcogen, such as Te, is effective in altering the conduction mechanism of transition-metal oxides and realizing a selector function.
Highlights
(product name), a Phase-change materials (PCMs)-based storage-class memory, was released by Intel.[10,11] The three-dimensional cross-point (3D XPoint) structure distinguishes it from other non-volatile memory (NVM) in the selector layer based on an Ovonic threshold switch (OTS) material.[10,11] In general, OTS materials are amorphous chalcogenides that exhibit nonlinear current (I)–voltage (V) characteristics and can achieve On–Off volatile switching, namely, a selector function.[12]
The three-dimensional cross-point (3D XPoint) structure distinguishes it from other NVMs in the selector layer based on an Ovonic threshold switch (OTS) material.[10,11]
In PF conduction, when the applied voltage is small or zero, the carriers exist at the localized level (Off state), but when a voltage above the threshold voltage (Vth) is applied, the potential barrier required for localization is lowered, resulting in the delocalization of the carriers (On state).[15,16]
Summary
(product name), a PCM-based storage-class memory, was released by Intel.[10,11] The three-dimensional cross-point (3D XPoint) structure distinguishes it from other NVMs in the selector layer based on an Ovonic threshold switch (OTS) material.[10,11] In general, OTS materials are amorphous chalcogenides that exhibit nonlinear current (I)–voltage (V) characteristics and can achieve On (low resistance)–Off (high resistance) volatile switching, namely, a selector function.[12]. Phase-change materials (PCMs) exhibit a large electrical contrast between the high-resistive amorphous and low-resistive crystalline phases.[1,2,3] The large contrast in resistance is a working principle in non-volatile memory (NVM) applications, where Ge–Sb–Te (GST)-based chalcogenides are the most mature.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
