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Atoms; Buffer layers; Cell engineering; Deposition; Gallium; Interfaces (materials); Magnetron sputtering; Nanotechnology; Optical properties; Optical waveguides; Photoelectrons; Photons; Probes; Solar cells; Thin film solar cells; Zinc, Alternative buffer layers; Atom probe tomography; Chemical characterization; Chemical fluctuations; CIGS; Nanoscale characterization; Postdeposition heat treatment; rf-Magnetron sputtering, X ray photoelectron spectroscopy
Abstract:
The buffer layers in Cu(In,Ga)Se2 solar cells play a crucial role in device performance, although their thickness is only a few tens of nanometers. Moreover, often Zn(S,O) alternative buffer layers have been studied in view of their structure, band alignment, and optical properties, but not much work exists on their nanoscale chemical properties. This work focuses on the chemical characterization of Zn(S,O) using x-ray photoelectron spectroscopy for determination of the Zn(S,O) and Cu(In,Ga)Se2 depth composition, and atom probe tomography for probing the nano-scale chemical fluctuations at the Zn(S,O)/Cu(In,Ga)Se2 interface. The Zn(O,S) buffer layer was deposited by RF magnetron sputtering. The aim is to study the nanoscale concentration changes and atomic interdiffusion between CIGS and Zn(S,O) after sputter deposition at room temperature and after post-deposition heat treatment at 200°C. © 2015 IEEE.
