Spectroscopic ellipsometry and optical transmission study of LiPON thin films prepared by RF sputtering

Su, Yongfu; Zhang, Jia; Shokhovets, S.; Polity, A.; Meyer, B. K.

doi:10.1002/pssb.201600424

Cited by 9 publications

(9 citation statements)

References 22 publications

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“…The ALD‐coated pellet, as in Figure 2C, appeared unchanged after ALD coating due to the material being thin and having a large bandgap. [ 24,25 ] Furthermore, no degradation of the pellets was detected as a result of the ALD processing.…”

Section: Resultsmentioning

confidence: 99%

Ion‐Conducting, Electron‐Blocking Layer for High‐Performance Solid Electrolytes

Hitz

Lin

et al. 2021

Small Structures

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Lithium metal batteries bring greater promise for energy density, often relying on solid‐state electrolytes to meet critical benchmarks. However, Li dendrite formation is a prevailing problem that limits the cycle life and Coulombic efficiency of solid‐state Li metal batteries. For the first time, a thin (<100 nm) layer of electronically insulating, ionically conducting lithium phosphorus oxynitride (LiPON) is applied using atomic layer deposition between a Li anode and garnet Li7La3Zr2O12 (LLZO). The performance of a conformal LiPON layer as an electron barrier in symmetric Li‐LLZO cells is observed through potential step chronoamperometry, galvanostatic cycling, electron microscopy, and various spectroscopic techniques. The LiPON‐coated LLZO achieves 100 times lower electronic conductance than LLZO alone. Cycling carried out at 0.1 mA cm−2 for 100 cycles demonstrates that suppression of electron pathways into the bulk solid electrolyte improves the cycle life of a lithium metal cell. These findings suggest an electronic conductivity effect in solid‐state electrolytes. A strategy is demonstrated to design thin‐film (LiPON)‐modulated bulk solid‐state electrolytes (LLZO) capable of maintaining high ionic conductivity and electrochemical stability while reducing the effective electronic conductivity, which results in significantly decreased dendrite formation, improved cycle life, and greater interfacial integrity between the electrolyte and a Li anode.

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Section: Resultsmentioning

confidence: 99%

Ion‐Conducting, Electron‐Blocking Layer for High‐Performance Solid Electrolytes

Hitz

Lin

et al. 2021

Small Structures

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“…63 Consistent with previous reports for LiPON, the SE data for the films were well fitted with 𝐴 ≈ 1.7, and B and C ≈ 0, indicative of a nearly constant index of refraction over the measured bandwidth. 26,64 We also assume 𝑘(𝜆) = 0, where 𝑘 is the absorption coefficient. The optical model was externally verified via comparison with x-ray reflectivity (XRR) measurements and SEM/FIB cross sections of various reference samples, and all thickness measurements agreed to within 5%.…”

Section: In-situ Ellipsometrymentioning

confidence: 99%

Nanoscale Solid State Batteries Enabled by Thermal Atomic Layer Deposition of a Lithium Polyphosphazene Solid State Electrolyte

et al. 2017

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ABSTRACT:Several active areas of research in novel energy storage technologies, including threedimensional solid state batteries and passivation coatings for reactive battery electrode components, require conformal solid state electrolytes. We describe an atomic layer deposition (ALD) process for a member of the lithium phosphorus oxynitride (LiPON) family, which is employed as a thin film lithium-conducting solid electrolyte. The reaction between lithium tertbutoxide (LiO t Bu) and diethyl phosphoramidate (DEPA) produces conformal, ionically conductive thin films with a stoichiometry close to Li 2 PO 2 N between 250 and 300C. The P/N ratio of the films is always 1, indicative of a particular polymorph of LiPON which closely resembles a polyphosphazene. Films grown at 300C have an ionic conductivity of 6.51 (±0.36) × 10 −7 S/cm at 35C, and are functionally electrochemically stable in the window from 0 to 5.3V vs. Li/Li+. We demonstrate the viability of the ALD-grown electrolyte by integrating it into full solid state batteries, including thin film devices using LiCoO 2 as the cathode and Si as the anode operating at up to 1 mA/cm 2 . The high quality of the ALD growth process allows pinhole-free deposition even on rough crystalline surfaces, and we demonstrate the fabrication and operation of thin film batteries with the thinnest (<100nm) solid state electrolytes yet reported. Finally, we show an additional application of the moderate-temperature ALD process by demonstrating a flexible solid state battery fabricated on a polymer substrate.3

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“…For the simulations a 500 nm wide, 220 nm high Si waveguide covered with a multilayer stack composed of 300 nm V 2 O 5 , 350 nm LiPON, and 100 nm Ag was used, with a fixed wavelength of 1550 nm. The LiPON layer can be assumed to have no loss (transparent amorphousnet glass, k = 0 for λ = 1550 nm 46 ). However, as can be seen, most of the light is confined to the waveguide and only the evanescent field interacts with the cladding.…”

Section: Multilayer Stackmentioning

confidence: 99%

Self-Holding Optical Actuator Based on a Mixed Ionic–Electronic Conductor Material

et al. 2019

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A new approach for an optical actuator system based on mixed ionic–electronic conductor materials is proposed. The system actuates on light propagating in a waveguide implemented on a photonic integrated circuit by electrochemically changing the composition of the MIEC material, using the characteristic dependence of the optical properties upon stoichiometry. To realize this actuator, a multilayer stack was sputtered and characterized forming a battery-like system where ions reversibly travel from a Li-ion source to a Li x V2O5 layer, producing the desired change of the optical properties. Modal field FEM simulations were carried out to estimate the influence of the formed actuator on a waveguide fundamental mode implemented on the silicon on insulator platform. The time resolution of the actuator is estimated solving the diffusion profile of Li inside the Li x V2O5 coating and its evolution with time. Through simulations and measurements, promising results for a potential actuator system are shown, like small device length (<20 μm), low power consumption (∼10 pW per switch), reversibility, and long time stability.

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Spectroscopic ellipsometry and optical transmission study of LiPON thin films prepared by RF sputtering

Cited by 9 publications

References 22 publications

Ion‐Conducting, Electron‐Blocking Layer for High‐Performance Solid Electrolytes

Ion‐Conducting, Electron‐Blocking Layer for High‐Performance Solid Electrolytes

Nanoscale Solid State Batteries Enabled by Thermal Atomic Layer Deposition of a Lithium Polyphosphazene Solid State Electrolyte

Self-Holding Optical Actuator Based on a Mixed Ionic–Electronic Conductor Material

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