Band alignment between (100)Si and complex rare earth∕transition metal oxides

Afanasʼev, Valeri; Stesmans, André; Zhao, Chao; Caymax, Matty; Heeg, T.; Schubert, J.; Jia, Yufei; Schlom, D. G.; Lucovsky, G.

doi:10.1063/1.1829781

Cited by 145 publications

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“…As shown by Schlom and Haeni, 3 single crystals of these oxides show values of 20-35 which were also observed for amorphous LaScO 3 , GdScO 3 , and DyScO 3 films deposited on silicon ͑ =22-23͒. 4,5 In addition, these materials fulfill the requirements for large optical band gaps ͑5.6 eV͒ and band offsets ͑2 -2.5 eV͒, 6 while their amorphous phase is stable up to 1000°C ͑for GdScO 3 and DyScO 3 ͒. 4,5 Lanthanum lutetium oxide ͑LaLuO 3 ͒, as a member of this class of ternary oxides, is predicted to have similar properties.…”

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confidence: 94%

“…There is also a 0.7 eV wide "tail" of subthreshold PC consistent with earlier observations for rare earth scandate insulators. 6 The IPE of electrons from the VB of Si into the oxide CB is observed under positive metal bias. The threshold ⌽ e was determined using the Y 1/3 -h plot 12 as illustrated in the inset in Fig.…”

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confidence: 99%

“…11 IPE and PC experiments were performed using MOS capacitors fabricated by evaporation of semitransparent ͑15 nm thick͒ Au electrodes of 0.5 mm 2 area using an experimental arrangement described earlier. 6 The quantum yield of IPE or PC was defined as the photocurrent, normalized to the incident photon flux. The square root of this quantum yield is shown in Fig.…”

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confidence: 99%

“…A combination of internal photoemission ͑IPE͒ and photoconductivity ͑PC͒ measurements was employed to determine the band gap width of the oxide and the conduction and valence band ͑CB, VB͒ offsets at the Si/highinterface. 6 For the electrical characterization of the films, capacitor stacks were prepared. 70 nm thick Pt top contacts with an area of 245ϫ 245 m 2 were deposited by electron beam evaporation through a shadow mask.…”

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Amorphous lanthanum lutetium oxide thin films as an alternative high-κ gate dielectric

Lopes

Roeckerath

Heeg

et al. 2006

Applied Physics Letters

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Lanthanum lutetium oxide thin films were grown on ͑100͒ Si by pulsed laser deposition. Rutherford backscattering spectrometry, atomic force microscopy, x-ray diffraction, and x-ray reflectometry were employed to investigate the samples. The results indicate the growth of stoichiometric and smooth LaLuO 3 films that remain amorphous up to 1000°C. Internal photoemission and photoconductivity measurements show a band gap width of 5.2± 0.1 eV and symmetrical conduction and valence band offsets of 2.1 eV. Capacitance and leakage current measurements reveal C-V curves with a small hysteresis, a dielectric constant of Ϸ32, and low leakage current density levels. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2393156͔The study of ultrathin gate dielectrics has recently gained great attention due to the technological need to replace SiO 2 films in metal-oxide-semiconductor field-effect transistors ͑MOSFETs͒. 1 The scaling has led to MOSFETs with ultrashort physical gate lengths ͑Ͻ50 nm͒ and insulating SiO 2 -based films with thickness less than 1 nm. At such a thickness, these films suffer from excessively high leakage of charge carriers and poor reliability with respect to dielectric breakdown. Therefore, to overcome these limitations new gate dielectric materials with a higher dielectric constant must be developed to replace the SiO 2 . According to the International Technology Roadmap for Semiconductors, 2 the implementation of high-gate dielectrics with a dielectric constant between 10 and 20 will be required by 2008, which will later be replaced by materials having a larger than 20, in order to meet both low leakage current density and performance requirements.Ternary rare earth oxides ͑e.g., DyScO 3 and GdScO 3 ͒ are emerging as promising candidates for high-applications. As shown by Schlom and Haeni, 3 single crystals of these oxides show values of 20-35 which were also observed for amorphous LaScO 3 , GdScO 3 , and DyScO 3 films deposited on silicon ͑ =22-23͒. 4,5 In addition, these materials fulfill the requirements for large optical band gaps ͑5.6 eV͒ and band offsets ͑2 -2.5 eV͒, 6 while their amorphous phase is stable up to 1000°C ͑for GdScO 3 and DyScO 3 ͒. 4,5 Lanthanum lutetium oxide ͑LaLuO 3 ͒, as a member of this class of ternary oxides, is predicted to have similar properties. 3,7 Experimental data related to high-gate applications of amorphous LaLuO 3 films are, however, still not available. In this letter, we present the results of a systematic study on the microstructural and electrical properties of amorphous LaLuO 3 thin films, deposited on silicon substrates by means of pulsed laser deposition ͑PLD͒.LaLuO 3 films were deposited by PLD using a stoichiometric ceramic target. The target was made by milling a stoichiometric mixture of Lu 2 O 3 ͑Alfa Aesar, 99.99%͒ and La 2 O 3 ͑Alfa Aesar, 99.999%͒ powders with a molar ratio of 1:1. The ground powder was dried and then fired at 1300°C in air for 12 h. After regrinding, the powder was pressed with a uniaxial press ͑3 tons͒. The pellets were the...

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Amorphous lanthanum lutetium oxide thin films as an alternative high-κ gate dielectric

Lopes

Roeckerath

Heeg

et al. 2006

Applied Physics Letters

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“…While XPS to some extent still requires careful attention to charging effects as a result of electron emission from the insulator, [2][3][4][5] IPE seems easier to control from this point of view. 6 Energy offset values, obtained by IPE for a number of high-k oxides, have been published in the past decade [7][8][9][10][11][12] and detailed reviews of the technique have been released. 6,12 The majority of measured data in all these cases has followed a mainstream method for establishing DE values, which has settled the barrier value DE C between the conduction bands of silicon and most high-k oxides to a range of 2.0-2.1 eV.…”

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A model for internal photoemission at high-k oxide/silicon energy barriers

Engström

2012

Journal of Applied Physics

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A model has been developed to describe the emission of electrons from silicon across the oxide energy barrier of metal-oxide-silicon structures. An optical absorption coefficient, exclusively describing the transmission of electrons which are emitted across the barrier, is split from the corresponding experimental quantity for the entire absorption range. This makes it possible to approximate the photo yield in terms of absorption coefficients and density of states without need for explicitly calculated matrix elements of optical transitions. Using this method, theoretical emission yield curves are found in good agreement with measured data. An important conclusion from this work is that values of oxide energy barrier heights should be extracted from different features of the yield data than most often done in the literature. This replaces a commonly used practice for determining the barrier heights, which is shown to be based on optical bulk properties of the silicon crystal. V C 2012 American Institute of Physics. [http://dx

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Passivating Polycrystalline Copper with an Ultrathin Samarium Layer

Abrahamczyk,

Walker,

Han

et al. 2024

Adv Eng Mater

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We report how a layer of samarium (Sm) with a thickness equivalent to ∼ 2 atoms (0.8 nm) deposited by thermal evaporation is remarkably effective at passivating polycrystalline copper (Cu) towards oxidation in ambient air. To monitor the rate of Cu oxidation in real time, slab‐like Cu films with a thickness of 9 nm were fabricated on glass modified with a layer of 3‐mercaptopropyl silatrane, which immobilises condensing Cu atoms by reaction with the thiol moiety, promoting slab‐like film formation at very low thickness. Upon exposure to ambient air the rate of increase in electrical resistance due to reaction with oxygen and water is slowed by more than an order of magnitude when the Cu film is capped with the ultra‐thin Sm layer. After 1 year the resistance increases by ∼30% as compared to ∼190% for Cu films without an ultra‐thin Sm layer. Photoelectron spectroscopy, atomic force microscopy and Kelvin probe measurements shed light on the underlying mechanism of passivation. Additionally, the ultra‐thin Sm layer is greatly lowering the work function of polycrystalline Cu films making this approach attractive for applications requiring a low work function electrode with high stability in air.This article is protected by copyright. All rights reserved.

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Band alignment between (100)Si and complex rare earth∕transition metal oxides

Cited by 145 publications

References 17 publications

Amorphous lanthanum lutetium oxide thin films as an alternative high-κ gate dielectric

Amorphous lanthanum lutetium oxide thin films as an alternative high-κ gate dielectric

A model for internal photoemission at high-k oxide/silicon energy barriers

Passivating Polycrystalline Copper with an Ultrathin Samarium Layer

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