Te-based chalcogenide materials for selector applications

Abstract

The implementation of dense, one-selector one-resistor (1S1R), resistive switching memory arrays, can be achieved with an appropriate selector for correct information storage and retrieval. Ovonic threshold switches (OTS) based on chalcogenide materials are a strong candidate, but their low thermal stability is one of the key factors that prevents rapid adoption by emerging resistive switching memory technologies. A previously developed map for phase change materials is expanded and improved for OTS materials. Selected materials from different areas of the map, belonging to binary Ge-Te and Si-Te systems, are explored. Several routes, including Si doping and reduction of Te amount, are used to increase the crystallization temperature. Selector devices, with areas as small as 55 × 55 nm2, were electrically assessed. Sub-threshold conduction models, based on Poole-Frenkel conduction mechanism, are applied to fresh samples in order to extract as-processed material parameters, such as trap height and density of defects, tailoring of which could be an important element for designing a suitable OTS material. Finally, a glass transition temperature estimation model is applied to Te-based materials in order to predict materials that might have the required thermal stability. A lower average number of p-electrons is correlated with a good thermal stability.

Towards a 3D GeSbTe phase change memory with integrated selector by non-aqueous electrodeposition

“…28,29 If a correct implementation of PCM memory Schottky barrier can be found this would result in a build-in selector and provide the ability to efficiently scale passive matrices. 30 The last and most conspicuous advantage of electrodeposition is that it is not a line-of-sight technique. True 3D memory in which the lithographic steps do not scale with the number of layers, similar to what has been demonstrated for Flash memory has not yet been realised for novel non-volatile memory.…”

Analysis of the threshold switching mechanism of a Te–SbO selector device for crosspoint nonvolatile memory applications

“…Various selector devices have been reported, for example, metal-insulator transition materials, 2 mixed ionic electronic conduction materials, 3 varistor-type diodes, 4 field assisted superlinear threshold devices, 5 and Ag or Cu/HfO 2 based selector devices. 6,7 In addition, Ovonic threshold switching (OTS) 8 devices using amorphous chalcogenide materials have been highlighted with good endurance and fast switching speed. 9,10 Amorphous chalcogenide materials with metal-insulatormetal (MIM) structures exhibit electrical characteristics in which a high-resistance state (off state) and a low-resistance state (on state) are reversibly repeated according to an applied electric field.…”

Recent Advances of Volatile Memristors: Devices, Mechanisms, and Applications

“…can be roughly grouped into oxides (such as SiO 2 , [17,21] HfO 2 , [18,23] TiO 2 , [19] ZnO, [20] CuO, [14] CoO, [22] ZrO 2 , [24] NbO x , [25] and VO 2 [26] ), 2D materials (e.g., h-BN, [13] WSe 2 , [16] MoS 2 , [27] and MoS 2 / graphene [35] ), perovskites (e.g., Cs 3 Sb 2 Br 9 [32] and MAPbI 3 [33] ), chalcogenides (such as AsTeSi, [29] GeTe, [30] and GeTe 8 [28] ), and others (e.g., PEDOT:PSS, [34] ferritin [31] ).…”

“…So far, large amounts of materials have been reported as electrodes for volatile memristors. We grouped the common electrode materials into four categories based on composition of electrodes, including pure metal electrodes such as Au, [32] Ag, [16] Cu, [21] Pt, [18] W, [34] and Ti; [20] nitride-based electrodes such as TiN; [23,30] conductive oxide-based electrodes such as ITO; [22,33] and semiconductor electrodes such as Si [25] and so on.…”