ECALE technique atomic layer epitaxy

The electrochemical atomic layer epitaxy (ECALE) technique, also known as electrochemical atomic layer deposition (EC-ALD), is based on layer-by-layer electrodeposition. Each constituent of the thin him are deposited separately using underpotential deposition (UPD) of that element. UPD is a process wherein an atomic layer of one element is deposited on the surface of a different element at a potential under that needed to deposit the element on itself. ECALE has been used to grow mainly II-VI and III-V compounds. A thorough review of ECALE research has been published by Stickney.144 A summary of the materials deposited using ECALE are given in Table 8.4, with a more detailed discussion for a few select examples given below. 

Atomic layer epitaxy (electrochemical) — Electrochemical atomic layer epitaxy (ECALE) is a self-limiting process for the formation of structurally well-ordered thin film materials. It was introduced by Stickney and coworkers [i] for the layer by layer growth of compound semiconductors (CdTe, etc.). Thin layers of compound semiconductors can be formed by alternating - underpotential deposition steps of the individual elements. The total number of steps determines the final thickness of the layer. Compared to flux-limited techniques... 

A similar UPD technique called electrochemical atomic layer epitaxy" (ECALE) was introduced by Stickney et al. [6.170-6.172] to form mbced 2D MexMey UPD overlayers using simultaneously electrochemical reduction and oxidation of different electrolyte components. 

Metal compound semiconductors such as CdS, CdSe, Hg(i CdjTe, BijScj, and InAs can also be produced by electrodeposition. Films of these materials have been produced by codeposition of the elements,or by a technique known as electrochemical atomic layer epitaxy (ECALE). 2-5s In codeposition, the films or nanostructures are produced from solution precursors by EC reactions, such as those shown in Equations 17.3 through 17.5. ECALE is the electrochemical equivalent of atomic layer epitaxy (ALE), because the material is assembled monolayer-by-monolayer using surface-limited reactions. The alternating layers in ECALE are deposited by UPD. 

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