Structural and Electrical Properties of Lanthanum Gadolinium Oxide: Ceramic and Thin Films for High-k Application

Pavunny, Shojan P.; Thomas, Reji; Murari, Nishit M.; Schubert, J.; Niessen, V.; Lupták, R.; Kalkur, T. S.; Katiyar, Ram S.

doi:10.1080/10584587.2011.574039

Cited by 25 publications

(23 citation statements)

References 12 publications

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“…19 For dielectric characterization, LGO pellets of 1 mm thickness and 7 mm diameter were DC sputtered at room temperature with Pt to form the top and bottom electrodes. The resulting MIM structures were annealed at 400 C in air for proper adhesion of Pt and recovery of the possible sputter damage.…”

Section: Methodsmentioning

confidence: 99%

Dielectric properties and electrical conduction of high-k LaGdO3 ceramics

Pavunny¹,

Thomas²,

Kumar³

et al. 2012

Journal of Applied Physics

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The temperature and frequency dependent dielectric properties and leakage conduction mechanism in LaGdO3 (LGO) ceramics have been studied, and this material has been identified as a potential high-k candidate for the future complementary metal-oxide-semiconductor (CMOS) and dynamic random access memory (DRAM) technology nodes. The dielectric constant and the loss tangent at 100 kHz were ∼21.5 and ∼0.003, respectively, at ambient conditions without any significant temperature and voltage dependence. The ac conductivity shows the typical features of universal dynamic response (UDR) and obey the double power law σac=σdc+Aωn1+Bωn2 with three types of temperature dependent conduction processes involved; (i) a dc plateau (< 3 kHz) due to long range translational hopping, (ii) a mid frequency region due to the short range hopping (3–100 kHz), and (iii) a high frequency region due to localized or reorientational hopping (100–1000 kHz). The temperature dependent dc conductivity follows the Arrhenius relation with activation energies of 0.05 eV in the 200–400 K range and 0.92 eV in the 400–600 K range. The leakage current behavior reveals bulk limited Poole-Frenkel (PF) conduction mechanism and the estimated optical dielectric constant (ɛ∞) is 3.6.

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Section: Methodsmentioning

confidence: 99%

Dielectric properties and electrical conduction of high-k LaGdO3 ceramics

Pavunny¹,

Thomas²,

Kumar³

et al. 2012

Journal of Applied Physics

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“…The calculated electronic dielectric constant is small in comparison with the dielectric constant (ε r = ε ∞ + ε l ) of LGO ∼ 21.6 ± 1.7 4 and we conclude that this oxide has a lattice dielectric constant (ε l ) much bigger than its electronic counterpart. The observed trend in average refractive index with decreasing film thickness implies that there might exist an interlayer of La-Gd silicates with a higher refractive index at the heterostructure interface and this transitional region possesses a larger percentage of the film as the film thickness decreases.…”

Section: Discussionmentioning

confidence: 88%

Optical Dielectric Function Modeling and Electronic Band Lineup Estimation of Amorphous High-k LaGdO₃Films

Pavunny

Thomas

Kumar

et al. 2012

ECS J. Solid State Sci. Technol.

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Optical constants of pulsed laser ablated amorphous high-k LaGdO 3 (a-LGO) thin films on quartz (0001) substrates were measured and analyzed. Refractive index (n ∼ 2.05-2.29) and extinction coefficient (k ∼ 0.004-0.017) were parameterized by analysis of the UV/Visible transmission spectra employing a Cauchy-Urbach dispersion model in the 300-750 nm spectral window and confirmed the applicability of this model in this wavelength region. The composition and chemistry of these dielectric films were studied by utilizing ATR-FTIR spectroscopy. The deduced pinning factor (S), 0.5 suggests that LGO/Si is an interacting interface. The parameter S was applied in the Cowley-Sze relation to estimate the interface trap density (D it ) to be 1.08 × 10 13 states cm −2 eV −1 . As grown LGO/p-Si heterojunction showed a downward Fermi-level (FL) pinning of 0.39 ± 0.02 eV. A complete Type I straddled band lineup of this gate dielectric/semiconductor heterostructure was determined by applying the charge neutrality level (CNL) model. The CNL of LGO was deduced to be 2.11 ± 0.05 eV above valence band maximum.In order to maintain the exponential growth of processing speed and component density, the feature sizes of metal-oxidesemiconductor field effect transistors (MOSFETs) in CMOS devices and metal-insulator-metal (MIM) stacks in DRAM devices, are downscaled from one technology node to another. In logic devices an equivalent oxide thickness (EOT) below 0.9 nm is required in the future ≤22 nm technology nodes. Such a lower EOT may be unfeasible with the presently used nitrided hafnium silicates based gate oxide materials due to their relatively low dielectric constant of 12-15. In order to achieve long term goals, another class of dielectrics with even higher dielectric constants, ε r >20, reduced dielectric loss and lower leakage currents are needed. In this regard, amorphous rare-earth-based, multi-component oxides with better thermal stability and higher crystallization temperature are found to be promising candidates for the next generation. 1-4 J ∼ exp[−(2m * E C ) 1/2 (ε r /3.9)d][ 1 ]One may note that La and Gd metal ions with +3 valencies are expected to form a charge neutrality level (CNL) at the lower half of the energy gap and have a higher barrier height for electrons ( E C ) than for holes ( E V ). Since tunneling current (J) holds an inverse relation with the conduction barrier offset ( E C ) as well as layer thickness (d), effective tunneling mass (m*) and dielectric constant (ε r ) of high-k material 5 (Eq.

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“…X-ray photoelectron spectroscopy (XPS) was employed to study the elemental composition, empirical formula, chemical state and electronic state (+3) of the elements that exist in the compound [14]. …”

Section: Qualification Of Lagdo3 As a Potential High-k Dielectricmentioning

confidence: 99%

Lanthanum Gadolinium Oxide: A New Electronic Device Material for CMOS Logic and Memory Devices

2014

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A comprehensive study on the ternary dielectric, LaGdO3, synthesized and qualified in our laboratory as a novel high-k dielectric material for logic and memory device applications in terms of its excellent features that include a high linear dielectric constant (k) of ~22 and a large energy bandgap of ~5.6 eV, resulting in sufficient electron and hole band offsets of ~2.57 eV and ~1.91 eV, respectively, on silicon, good thermal stability with Si and lower gate leakage current densities within the International Technology Roadmap for Semiconductors (ITRS) specified limits at the sub-nanometer electrical functional thickness level, which are desirable for advanced complementary metal-oxide-semiconductor (CMOS), bipolar (Bi) and BiCMOS chips applications, is presented in this review article.

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Structural and Electrical Properties of Lanthanum Gadolinium Oxide: Ceramic and Thin Films for High-k Application

Cited by 25 publications

References 12 publications

Dielectric properties and electrical conduction of high-k LaGdO3 ceramics

Dielectric properties and electrical conduction of high-k LaGdO3 ceramics

Optical Dielectric Function Modeling and Electronic Band Lineup Estimation of Amorphous High-k LaGdO₃Films

Lanthanum Gadolinium Oxide: A New Electronic Device Material for CMOS Logic and Memory Devices

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Structural and Electrical Properties of Lanthanum Gadolinium Oxide: Ceramic and Thin Films for High-k Application

Cited by 25 publications

References 12 publications

Dielectric properties and electrical conduction of high-k LaGdO3 ceramics

Dielectric properties and electrical conduction of high-k LaGdO3 ceramics

Optical Dielectric Function Modeling and Electronic Band Lineup Estimation of Amorphous High-k LaGdO3Films

Lanthanum Gadolinium Oxide: A New Electronic Device Material for CMOS Logic and Memory Devices

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Optical Dielectric Function Modeling and Electronic Band Lineup Estimation of Amorphous High-k LaGdO₃Films