Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

Abstract

a b s t r a c tElectrochemical Atomic Layer Deposition (E-ALD), exploiting surface limited electrodeposition of atomic layers, can easily grow highly ordered ultra-thin films and 2D structures. Among other compounds Cu x Zn y S grown by means of E-ALD on Ag(111) has been found particularly suitable for the solar energy conversion due to its band gap (1.61 eV). However its growth seems to be characterized by a micrometric thread-like structure, probably overgrowing a smooth ultra-thin films. On this ground, a SXRD investigation has been performed, to address the open questions about the structure and the growth of Cu x Zn y S by means of E-ALD. The experiment shows a pseudo single crystal pattern as well as a powder pattern, confirming that part of the sample grows epitaxially on the Ag(111) substrate. The growth of the film was monitored by following the evolution of the Bragg peaks and Debye rings during the E-ALD steps. Breadth and profile analysis of the Bragg peaks lead to a qualitative interpretation of the growth mechanism. This study confirms that Zn lead to the growth of a strained Cu 2 S-like structure, while the growth of the thread-like structure is probably driven by the release of the stress from the epitaxial phase.

On the Electrochemical Growth of a Crystalline p–n Junction From Aqueous Solutions

“…The S hexagonal planes are not parallel to any of the mono‐clinic surfaces of the unit cell. E‐ALD growth of Cu 2 S results in crystallographically well‐ordered films, whose structure seems compatible with the one reported in, [29] and with a growth direction perpendicular to the S hexagonal planes [30,31] . The observed distance between two S layers is 0.675 nm, [31] very close to half of the periodicity along c noticed by Evans; [29] considering that in the structure this distance corresponds to two bilayers of Cu 2 S, with 60 deposition cycles the theoretical thickness of the Cu 2 S layer is again 20 nm.…”

In-situ Quantification of Nanoparticles Oxidation: A Fixed Energy X-ray Absorption Approach

“…This particular set-up permits both to avoid signal variations due to changes in the incoming photon beam (by simple normalization of the sample signal using I 0 ) and to calibrate the acquisition energy through the simultaneous analysis of a Pd reference foil, located in a second analytical XAS chamber. The software ATHENA was used to average multiple spectra and extract the normalised absorption edge [56][57][58].…”

Investigations on the Electrochemical Atomic Layer Growth of Bi2Se3 and the Surface Limited Deposition of Bismuth at the Silver Electrode

“…E-ALD exploits Surface-Limited Reactions (SLRs), such as Underpotential Deposition (UPD), thus achieving the layer-by-layer growth of various compound semiconductors [8,9,10,11,12,13,14,15,16,17]. The Nernst equation predicts the redox potential necessary to reduce metal ion A onto a substrate of the same element A.…”