Device and method for the electrochemical deposition of chemical compounds and alloys with controlled composition and/or stoichiometry

Abstract

Disclosed is a method for depositing an alloy and / or chemical compounds on a substrate immersed in an electrolyte (1), comprising the steps of: I) applying a first constant or varying potential to the substrate under voltage control for a first time interval (tA); II) applying a second constant or varying current to the substrate under current control for a second time interval (tB); repeating the sequence of steps (I-II). at least twice. Further the use of the method in particular for the deposition of Bi2+xTe3−x is disclosed as well as a specific device for carrying out the above method.

Description

TECHNICAL FIELD[0001]The presented invention relates to a method for depositing an alloy and / or chemical compounds on a substrate immersed in an electrolyte. It furthermore relates to the use of such a method for the deposition in particular of Bi2+xTe3−x coatings and it also relates to a specifically tailored device for the above method.BACKGROUND OF THE INVENTION[0002]Electrochemical deposition (ECD) is a well-known method to electrochemically deposit layers of metals, alloys or chemical substances on the surface or into a surface structure of a substrate to be treated.[0003]Electrochemical deposition is thus generally known and can be achieved by a variety of techniques. A typical electrochemical deposition method comprises the reduction of ions from aqueous, organic or fused salt electrolytes at the electrode-electrolyte interface forming a deposition. This deposition can be achieved in two different ways: a) with an electroless (autocatalytic) deposition process in which the el...

AI Technical Summary

Benefits of technology

The present invention provides an improved method for electrochemical deposition of chemical compounds or alloys on a substrate immersed in a liquid electrolyte. The method involves applying a sequence of voltage and current control steps, which includes a first constant or varying potential for a first time interval, followed by a second constant or varying current for a second time interval. These steps can be carried out using a three-electrode system, including a reference electrode, a working electrode, and a counter electrode. The method allows for controlled deposition of chemical compounds or alloys with improved stoichiometry and morphology control, while also reducing current flow and improving deposition rates.

Problems solved by technology

For the deposition of certain alloy and compounds using conventional electrochemical deposition processes may lead to problematic layer properties and material properties like for example insufficient adhesion, internal stress or undesired physical properties etc.

These problems are due to variations in the stoichiometry / composition across the thickness of the layer which in turn are due to lack of control during the deposition process.

This insufficient stoichiometric control during the deposition is inherent to the processes according to the state-of-the-art.

However, during the relaxation period for certain electrochemical systems, e.g. Bi2+xTe3−x the problem of undesired reactions on the deposition electrode occurs, which are caused by shifting of the equilibrium potential.

The current controlled pulsed electrochemical deposition is problematic in the sense that the deposition processes during the deposition period cannot be completely controlled.

Unfortunately few measurements have been made to investigate the stoichiometry across the thickness of electrochemically deposited Bi2Te3 layers.

However discrepancies illustrate the necessity of investigations on the stoichiometric profile and of means to control the deposition process in such a way, that a homogeneous stoichiometry is achieved throughout the entire layer.

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