Electrodeposition of CU₂SE thin films by Electrochemical Atomic Layer Epitaxy (EC-ALE).

Abstract

Electrochemical atomic-layer epitaxy (EC-ALE) is an approach to electrodepositing thin-films of compound semiconductors. It takes advantage of underpotential deposition (UPD), deposition of a surface limited amount (a monolayer or less) of an element at a potential less negative than bulk deposition, to form a thin-film of a compound--one atomic layer at a time. Ideally, the 2-D growth mode should promote epitaxial deposition.

Potential Pulse Atomic Layer Deposition of Cu2Se

“…As with deposit thickness (Figure , red line), there was essentially no variation in stoichiometry as a function of the Cathodic potential, while the Anodic was held at 50 mV (Figure , red line), since any excess Cu is removed completely. EPMA indicated a stoichiometry of Cu 2.5 Se 1 rather than the expected Cu 2 Se 1 ratio, expected from the literature ,, and by XRD. Subsequent analysis using the EDS system on a FEI Inspect SEM, however, indicated the expected Cu 2 Se 1 ratio.…”

“…The biggest drawback is the slow deposition rate, as there are multiple solution exchanges each cycle. The technique is thus best applied when nanofilms of a carefully controlled thickness and quality are required and the total number of cycles performed is minimized. , Given the time required to grow micrometer thick absorber layers, E-ALD is generally impractical compared with coelectrodeposition, which has been used by BP to commercially electrodeposit micrometer thick CdTe PV absorber layers. , …”

“…The technique is thus best applied when nanofilms of a carefully controlled thickness and quality are required and the total number of cycles performed is minimized. 42,48 Given the time required to grow micrometer thick absorber layers, E-ALD is generally impractical compared with coelectrodeposition, which has been used by BP to commercially electrodeposit micrometer thick CdTe PV absorber layers. 7,49 Coelectrodeposition has been used to form a large number of other compounds, 50,51 including CdSe.…”

Deposition of Sb2Se3 thin films on Pt substrate via electro-chemical atomic layer epitaxy (EC-ALE)

“…The concentration used in literature for Sb2O3 solutions [20,[24][25][26][27][28][29][30] ranges from 0.01 mM to 0.05mM, and we can confirm from experiment that 0.05 mM which is the most often used concentration, is higher than the solubility limit of antimony oxide in sulfuric acid solution. The concentration used in literature for SeO2 solutions [22,[31][32][33][34][35][36][37][38][39][40][41][42][43] ranges from 0.05 mM to 2 mM, with 0.5 mM as the most often used one. The pH values for all the solutions were adjusted to 1.00 with H2SO4.…”