American Chemical Society
am6b04000_si_001.pdf (978.22 kB)

ALD Zn(O,S) Thin Films’ Interfacial Chemical and Structural Configuration Probed by XAS

Download (978.22 kB)
journal contribution
posted on 2016-05-25, 00:00 authored by Anup L. Dadlani, Shinjita Acharya, Orlando Trejo, Fritz B. Prinz, Jan Torgersen
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.