Molecular adsorption characteristics of lanthanum oxide surfaces: the interaction of water with oxide overlayers grown on Cu(111)

Asha, A.M.; Critchley, John T. S.; Nix, Roger M.

doi:10.1016/s0039-6028(98)00044-2

Cited by 90 publications

(50 citation statements)

References 31 publications

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“…known that the chemical bonding in LaNIO 3 is not purely ionic, but exhibits covalent (Ni-O and La-O) and metallic (Ni-O-Ni) parts [25] that can explain the presence of two different oxides in the sample. As was mentioning above, the rare earth oxides are easily hygroscopic when they were exposed to atmospheric conditions [14]. Thus, an additional spectral component C at approximate 531 eV may be attributed to La and Ni hydroxides [23,26,27] for which O 1s BE is typically higher by a 2.0-2.5 eV in respect to the associated lattice oxygen [14].].…”

Section: Resultsmentioning

confidence: 97%

“…It is known that the rare earth oxides are easily hygroscopic when they were exposed to atmospheric conditions [14,15]. The study of interaction of water with lanthanum oxide by XPS, UPS and TDS study show that La 2 O 3 films rapidly adsorb water in a dissociate fashion, with an accompanying conversion of surface ions, to give a high concentration of surface hydroxyl groups [14].…”

Section: Resultsmentioning

confidence: 99%

“…The study of interaction of water with lanthanum oxide by XPS, UPS and TDS study show that La 2 O 3 films rapidly adsorb water in a dissociate fashion, with an accompanying conversion of surface ions, to give a high concentration of surface hydroxyl groups [14]. Wandelt and Brundle [15] have studied the interaction of oxygen with evaporated Gd films at room temperature by Al K␣ XPS and HeI and HeII UPS techniques.…”

Section: Resultsmentioning

confidence: 99%

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Investigation of epitaxial LaNiO3−x thin films by high-energy XPS

Mickevičius¹,

Grebinskij²,

Bondarenka³

et al. 2006

Journal of Alloys and Compounds

195

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Epitaxial thin films of LaNiO 3−x were deposited by using a reactive d.c. magnetron sputtering technique. High-energy X-ray photoelectron spectroscopy was used to analyze the composition and valence states of La and Ni in the films after long time aging in atmosphere. The obtained results show the existence lanthanum and nickel in oxide and hydroxide chemical states. The oxygen exists in four chemical states: lattice oxides, hydroxyl groups and in adsorbed water. Comparison of the spectra recorded at normal emission and grazing emission angle revealed that the hydroxyl group's concentration is mostly present at the surface of the film.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of epitaxial LaNiO3−x thin films by high-energy XPS

Mickevičius¹,

Grebinskij²,

Bondarenka³

et al. 2006

Journal of Alloys and Compounds

195

View full text Add to dashboard Cite

show abstract

“…For films fabricated using O 2 and O 3 , the thickness decreased as the dipping time increased. According to other studies [10][11], upon contact with water, La 2 O 3 changes to La(OH) 3 (lanthanum hydroxide) via a hydration reaction, which dissolves well in water. The hydration reaction causes a continuous decrease the thickness of La 2 O 3 films.…”

Section: Methodsmentioning

confidence: 88%

A study on the characteristics of hydrated La2O3 thin films with different oxidation gases on the various annealing temperature

2008

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In order to investigate the structural and electrical properties of La 2 O 3 films deposited by O 2 and O 3 , films were hydrated in DI-water and annealed at 600 and 900°C. La 2 O 3 films deposited by O 3 showed better hydration resistance than those deposited by O 2 . The thickness of both hydrated films decreased after annealing at 600°C and increased after annealing at 900°C. The dielectric constants of the La 2 O 3 films deposited by O 3 were greater than films deposited by O 2 after annealing at 600°C and slightly less after annealing at 900°C. The leakage current density of the La 2 O 3 films deposited by O 3 was lower than those by O 2 after annealing at 900°C. To this end, La 2 O 3 films deposited by O 3 showed better dissolution resistance than O 2 for hydration experiment as a function of dipping time.

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“…[11,12] This can result in oxygen vacancies and excess positive charge in the oxide film layer, leading to unwanted flat-band voltage shifts in the metal±oxide dielectric structure.…”

mentioning

confidence: 99%

Growth of Lanthanum Silicate Thin Films by Liquid Injection MOCVD Using Tris[bis(trimethylsilyl)amido]lanthanum

Aspinall

Williams²,

Gaskell

et al. 2003

Chemical Vapor Deposition

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The rapid growth of the silicon-based microelectronics industry since the late 1980s has fuelled a demand for greater integrated circuit functionality and improved performance at lower cost. This requires an increased circuit density, which has been achieved by a continual reduction, or ªscalingº, in the dimensions of the field-effect transistor (FET), [1] the fundamental active device in the silicon integrated circuit (IC). Key elements enabling the scaling of the Si-based metal±oxide±semiconductor field-effect transistor (MOSFET) are the materials and electrical properties of the dielectric layer employed to isolate the transistor gate from the Si channel. For many years, amorphous SiO 2 has been the chosen dielectric layer, due to its stable, high quality, Si±SiO 2 interface, and excellent electrical isolation properties.[2] The rapid shrinking of the transistor feature size has forced the channel length and gate dielectric thickness to also decrease rapidly, but as the dimensions of the SiO 2 layer approach 20±30 , direct electron tunneling effects and high leakage currents present serious obstacles to future device reliability. The use of materials with a higher dielectric constant (k) than SiO 2 allows an equivalent capacitance to be achieved in a physically thicker insulating layer, and thicker layers should, in turn, provide reduced leakage currents. Therefore, there has been much recent research aimed at replacing the conventional SiO 2 gate dielectric with alternative high k dielectric oxides such as Al 2 O 3 , [3] Ta 2 O 5 , [4] TiO 2 , [5] ZrO 2 , [6] HfO 2 , [7] and La 2 O 3 , [8] and their related silicates.[2]Of these materials, lanthanum oxide, La 2 O 3 , has good potential due to its relatively high permittivity, [9] but unfortunately La 2 O 3 is chemically unstable in air, reacting with CO 2 to form La 2 (CO 3 ) 3 , [10] and adsorbing water to give LaO(OH) and La(OH) 3 by an extensive surface hydroxylation process. [11,12] This can result in oxygen vacancies and excess positive charge in the oxide film layer, leading to unwanted flat-band voltage shifts in the metal±oxide dielectric structure.[8] Some recent research efforts have therefore focussed on the deposition and properties of lanthanum silicate (LaSi x O y ) films. [13,14] Although LaSi x O y films have a lower permittivity than La 2 O 3 , they are more stable and are less likely to contain oxygen deficiencies.There have been a number of recent studies into the deposition of La-containing insulators for gate dielectric applications. For example, some of the highest capacitance metal±insulator±silicon structures have been fabricated by the deposition of metallic La followed by low temperature oxidation. [15] However, the precise nature of these films is uncertain due to the ready formation of lanthanum silicate at the silicon±LaO x interface. For instance, a significant concentration of Si (~10 at.-%) was observed in LaO x films deposited by atomic beam deposition on a Si(100) substrate, [8] whilst a La±Si±O alloy was observed to form at ...

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Molecular adsorption characteristics of lanthanum oxide surfaces: the interaction of water with oxide overlayers grown on Cu(111)

Cited by 90 publications

References 31 publications

Investigation of epitaxial LaNiO3−x thin films by high-energy XPS

Investigation of epitaxial LaNiO3−x thin films by high-energy XPS

A study on the characteristics of hydrated La2O3 thin films with different oxidation gases on the various annealing temperature

Growth of Lanthanum Silicate Thin Films by Liquid Injection MOCVD Using Tris[bis(trimethylsilyl)amido]lanthanum

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