Oxygen vacancy formation and the induced defect states in HfO2 and Hf-silicates – A first principles hybrid functional study

Chen, Tsung-Ju; Kuo, Chin-Lung

doi:10.1016/j.microrel.2013.10.013

Cited by 8 publications

(6 citation statements)

References 34 publications

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“…[43,1,33] Upon annealing at temperatures above 400 -600 • C, dependant upon growth technique and substrate, the degree of crystalline character increases forming cubic and or monoclinic crystalline regions within the film, which at elevated temperatures > 900 • C give the completely poly-crystalline thin film. [6,72,30] The picture given by the XRD peaks is further confirmed when the partially crystalline and poly-crystalline films are studied using TEM, showing crystal like islands at the low end of the temperature scale. These structures expand as temperature is increased resulting in the high temperature poly-crystalline films.…”

Section: Introductionmentioning

confidence: 62%

Structural, elastic, vibrational and electronic properties of amorphous Sm2O3 from Ab Initio calculations

Olsson

Cai

Cottom

et al. 2019

Computational Materials Science

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Rare earth oxides have shown great promise in a variety of applications in their own right, and as the building blocks of complex oxides. A great deal of recent interest has been focused on Sm 2 O 3 , which has shown significant promise as a high-k dielectric and as a ReRAM dielectric. Experimentally, these thin films range from amorphous, through partially crystalline, to poly-crystalline, dependent upon the synthetic conditions. Each case presents a set of modelling challenges that need to be defined and overcome. In this work, the problem of modelling amorphous Sm 2 O 3 is tackled, developing an atomistic picture of the effect of amorphization on Sm 2 O 3 from a structural and electronic structure perspective.

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Section: Introductionmentioning

confidence: 62%

Structural, elastic, vibrational and electronic properties of amorphous Sm2O3 from Ab Initio calculations

Olsson

Cai

Cottom

et al. 2019

Computational Materials Science

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“…the HfOx layer owing to the presence of oxygen vacancies in the HfOx. [60][61][62][63] Nevertheless, HfOx is able to accept oxygen only to some extent. Oxygen anions not able to enter the HfOx lattice are involved in the oxidation of a fraction of CoO to Co3O4 (Figure 8e).…”

Section: Resultsmentioning

confidence: 99%

“…More specifically, as depicted in Figure d,e, the application of negative voltage to the Co–Pt/HfO x system triggers the diffusion of O 2– ions from the Co–Pt film toward the HfO x layer, resulting in the partial reduction of Co 3 O 4 to CoO and the reduction of CoO to metallic Co. Unlike the uncoated Co–Pt films, for which O 2– migration was limited to the surface, oxygen ions can diffuse here within the HfO x layer owing to the occurrence of oxygen vacancies in HfO x . − Nevertheless, HfO x is able to accept oxygen only to some extent. Oxygen anions not able to enter the HfO x lattice are involved in the oxidation of a fraction of CoO to Co 3 O 4 (Figure e).…”

Section: Resultsmentioning

confidence: 99%

Enhancing Magneto-Ionic Effects in Magnetic Nanostructured Films via Conformal Deposition of Nanolayers with Oxygen Acceptor/Donor Capabilities

Navarro-Senent

Quintana

Isarain‐Chávez

et al. 2020

ACS Appl. Mater. Interfaces

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Effective electric-field manipulation of the magnetic properties of nanostructured metallic alloys exhibiting inter-grain porosity (i.e., channels) conformally coated with insulating oxide nanolayers is demonstrated. Nanostructured Co-Pt films are prepared by electrodeposition (ED) and subsequently coated with either AlOx or HfOx by atomic layer deposition (ALD) to promote magneto-ionic effects (i.e., voltage-driven ion migration) during electrolyte-gating. Pronounced variations in coercivity (HC) and magnetic moment at saturation (mS) are observed at room temperature after biasing the heterostructures. The application of a negative voltage results in a decrease of HC and an increase of mS, whereas the opposite trend is achieved for positive voltages. Although magneto-ionic phenomena are already observed in uncoated Co-Pt films (due to the inherent presence of oxygen), the ALD oxide nanocoatings serve to drastically enhance the magneto-ionic effects due to partially reversible voltage-driven oxygen migration across the interface between AlOx or HfOx and the nanostructured Co-Pt film. Co-Pt/HfOx heterostructures exhibit the most significant magnetoelectric response at negative voltages, with an increase of mS up to 76% and a decrease of HC by 58%. The combination of a nanostructured magnetic alloy and a skin-like insulating oxide nanocoating is shown to be appealing to enhance magneto-ionic effects, potentially enabling electrolyte-gated magneto-ionic technology.

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“…5(b), which is agreed with the trapping energy of V o in α-HfO x . [34] The conduction in the LRS could thus be governed by a Poole-Frenkel emission mechanism with the V o s assisting electron transport in the HfO x .…”

Section: Switching Mechanism Of the Rramsmentioning

confidence: 99%

Thermal stability and data retention of resistive random access memory with HfO _x /ZnO double layers

et al. 2017

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As an industry accepted storage scheme, hafnium oxide (HfO x ) based resistive random access memory (RRAM) should further improve its thermal stability and data retention for practical applications. We therefore fabricated RRAMs with HfO x /ZnO double-layer as the storage medium to study their thermal stability as well as data retention. The HfO x /ZnO double-layer is capable of reversible bipolar switching under ultralow switching current (< 3 µA) with a Schottky emission dominant conduction for the high resistance state and a Poole-Frenkel emission governed conduction for the low resistance state. Compared with a drastically increased switching current at 120 • C for the single HfO x layer RRAM, the HfO x /ZnO double-layer exhibits excellent thermal stability and maintains neglectful fluctuations in switching current at high temperatures (up to 180 • C), which might be attributed to the increased Schottky barrier height to suppress current at high temperatures. Additionally, the HfO x /ZnO double-layer exhibits 10-year data retention @85 • C that is helpful for the practical applications in RRAMs.

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Oxygen vacancy formation and the induced defect states in HfO2 and Hf-silicates – A first principles hybrid functional study

Cited by 8 publications

References 34 publications

Structural, elastic, vibrational and electronic properties of amorphous Sm2O3 from Ab Initio calculations

Structural, elastic, vibrational and electronic properties of amorphous Sm2O3 from Ab Initio calculations

Enhancing Magneto-Ionic Effects in Magnetic Nanostructured Films via Conformal Deposition of Nanolayers with Oxygen Acceptor/Donor Capabilities

Thermal stability and data retention of resistive random access memory with HfO _x /ZnO double layers

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Oxygen vacancy formation and the induced defect states in HfO2 and Hf-silicates – A first principles hybrid functional study

Cited by 8 publications

References 34 publications

Structural, elastic, vibrational and electronic properties of amorphous Sm2O3 from Ab Initio calculations

Structural, elastic, vibrational and electronic properties of amorphous Sm2O3 from Ab Initio calculations

Enhancing Magneto-Ionic Effects in Magnetic Nanostructured Films via Conformal Deposition of Nanolayers with Oxygen Acceptor/Donor Capabilities

Thermal stability and data retention of resistive random access memory with HfO x /ZnO double layers

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Thermal stability and data retention of resistive random access memory with HfO _x /ZnO double layers