title: ALD Zn(O,S) Thin Films' Interfacial Chemical and Structural Configuration Probed by XAS.
abstract: The ability to precisely control interfaces of atomic layer deposited (ALD) zinc oxysulfide (Zn(O,S)) buffer layers to other layers allows precise tuning of solar cell performance. The O K- and S K-edge X-ray absorption near edge structure (XANES) of ∼2-4 nm thin Zn(O,S) films reveals the chemical and structural influences of their interface with ZnO, a common electrode material and diffusion barrier in solar cells. We observe that sulfate formation at oxide/sulfide interfaces is independent of film composition, a result of sulfur diffusion toward interfaces. Leveraging sulfur's diffusivity, we propose an alternative ALD process in which the zinc precursor pulse is bypassed during H2S exposure. Such a process yields similar results to the nanolaminate deposition method and highlights mechanistic differences between ALD sulfides and oxides. By identifying chemical species and structural evolution at sulfide/oxide interfaces, this work provides insights into increasing thin film solar cell efficiencies.
authors.affiliation: Department of Chemistry, ‡Department of Mechanical Engineering, and §Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Anup L
authors.initials: AL
authors.lastname: Dadlani
authors.affiliation: Department of Chemistry, ‡Department of Mechanical Engineering, and §Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Shinjita
authors.initials: S
authors.lastname: Acharya
authors.affiliation: Department of Chemistry, ‡Department of Mechanical Engineering, and §Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Orlando
authors.initials: O
authors.lastname: Trejo
authors.affiliation: Department of Chemistry, ‡Department of Mechanical Engineering, and §Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Fritz B
authors.initials: FB
authors.lastname: Prinz
authors.affiliation: Department of Chemistry, ‡Department of Mechanical Engineering, and §Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Jan
authors.initials: J
authors.lastname: Torgersen
keywords: X-ray absorption near edge structure (XANES); Zn(O,S); atomic layer deposition (ALD); electronic structure; ternary oxide films