{"title":"Effects of Plasma Reactants on Atomic Layer Deposition of Lithium Phosphate and Lithium Phosphorus Oxynitride Electrolyte Films","authors":"Tohru Tsuruoka*, Samapika Mallik, Takuji Tsujita, Yuu Inatomi and Kazuya Terabe, ","doi":"10.1021/acs.chemmater.4c00960","DOIUrl":null,"url":null,"abstract":"<p >The effects of plasma reactants on the plasma-assisted atomic layer deposition (ALD) of lithium phosphate are investigated in relation to the fabrication of high-quality lithium phosphorus oxynitride (LiPON) thin films for potential use as a solid-state electrolyte (SSE) in both microbatteries and neuromorphic devices. Our ALD processes enable the incorporation of nitrogen into a lithium phosphate matrix, using lithium <i>tert</i>-butoxide and tris(dimethylamino)phosphine as the lithium and phosphorus precursors, respectively, in a deposition temperature window of 220–300 °C. With O<sub>2</sub> plasma, polycrystalline lithium phosphate films, with a relatively well-arranged pyrophosphate, are deposited. Amorphous LiPON films, with a mixture of pyrophosphates and orthophosphates, are obtained when Ar or NH<sub>3</sub> plasma is used. When the NH<sub>3</sub> flow rate increases, the nitrogen composition increases up to ∼13%, while residual carbon is kept below a few percent. For a Li<sub>2.5</sub>PO<sub>1.9</sub>N<sub>0.8</sub> film deposited at 300 °C with NH<sub>3</sub> plasma, the ionic conductivity is measured as 1.65 ± 0.42 × 10<sup>–6</sup> S/cm at 25 °C, with an activation energy of 0.66 eV. This conductivity is the highest value of any ALD LiPON film reported to date. Our ALD processes exhibit a high level of controllability of the molecular structures of the phosphorus oxynitride matrix with high ionic conductivity, which makes them suitable for realizing high-performance Li SSE thin films.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":null,"pages":null},"PeriodicalIF":7.2000,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemistry of Materials","FirstCategoryId":"88","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acs.chemmater.4c00960","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The effects of plasma reactants on the plasma-assisted atomic layer deposition (ALD) of lithium phosphate are investigated in relation to the fabrication of high-quality lithium phosphorus oxynitride (LiPON) thin films for potential use as a solid-state electrolyte (SSE) in both microbatteries and neuromorphic devices. Our ALD processes enable the incorporation of nitrogen into a lithium phosphate matrix, using lithium tert-butoxide and tris(dimethylamino)phosphine as the lithium and phosphorus precursors, respectively, in a deposition temperature window of 220–300 °C. With O2 plasma, polycrystalline lithium phosphate films, with a relatively well-arranged pyrophosphate, are deposited. Amorphous LiPON films, with a mixture of pyrophosphates and orthophosphates, are obtained when Ar or NH3 plasma is used. When the NH3 flow rate increases, the nitrogen composition increases up to ∼13%, while residual carbon is kept below a few percent. For a Li2.5PO1.9N0.8 film deposited at 300 °C with NH3 plasma, the ionic conductivity is measured as 1.65 ± 0.42 × 10–6 S/cm at 25 °C, with an activation energy of 0.66 eV. This conductivity is the highest value of any ALD LiPON film reported to date. Our ALD processes exhibit a high level of controllability of the molecular structures of the phosphorus oxynitride matrix with high ionic conductivity, which makes them suitable for realizing high-performance Li SSE thin films.
期刊介绍:
The journal Chemistry of Materials focuses on publishing original research at the intersection of materials science and chemistry. The studies published in the journal involve chemistry as a prominent component and explore topics such as the design, synthesis, characterization, processing, understanding, and application of functional or potentially functional materials. The journal covers various areas of interest, including inorganic and organic solid-state chemistry, nanomaterials, biomaterials, thin films and polymers, and composite/hybrid materials. The journal particularly seeks papers that highlight the creation or development of innovative materials with novel optical, electrical, magnetic, catalytic, or mechanical properties. It is essential that manuscripts on these topics have a primary focus on the chemistry of materials and represent a significant advancement compared to prior research. Before external reviews are sought, submitted manuscripts undergo a review process by a minimum of two editors to ensure their appropriateness for the journal and the presence of sufficient evidence of a significant advance that will be of broad interest to the materials chemistry community.