On the Growth, Percolation and Wetting of Silver Thin Films Grown by Atmospheric-Plasma Enhanced Spatial Atomic Layer Deposition

In this work we studied the deposition of silver (Ag) by spatial-ALD on molybdenum layers serving as a growth model substrate. Mo-layers were selected for testing the suitability of spatial-ALD in fabricating MoO3/Ag/MoO3 tri-layer transparent conductor (TC) stacks used for light-management optimization in organic-based and perovskites solar cells. The presence of native MoO3 on the Mo surface was found to hinder the Ag coalescence. Therefore, an H2/N2 plasma pre-treatment was introduced before Ag deposition in order to reduce the native MoO3. It was concluded that this plasma pre-treatment was effective in promoting Ag wetting, as corroborated by scanning electron microscopy and ellipsometry measurements. Wetting/de-wetting properties as probed by rapid thermal annealing experiments and comparable XRD stress amplitude measurements supported the conclusion that, plasma pre-treatment ALD deposited MoO3 layers can act as wetting layers for subsequent Ag spatial-ALD. This can open up alternative pathways for the fabrication of TCs using ALD.