Atomic Layer Deposition of ZnO on Mesoporous Silica: Insights into Growth Behavior of ZnO via In-Situ Thermogravimetric Analysis.

Piyush Ingale,Raoul Naumann D’Alnoncourt,Arne Thomas,Mar Piernavieja Hermida,Kristian Knemeyer,Frank Rosowski

doi:10.3390/nano10050981

Piyush Ingale, Raoul Naumann D’Alnoncourt + Show 4 more

Open Access

https://doi.org/10.3390/nano10050981

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Journal: Nanomaterials	Publication Date: May 20, 2020
Citations: 15	License type: CC BY 4.0

Affiliation: Technische Universität Berlin, BASF (Germany)

Abstract

ZnO is a remarkable material with many applications in electronics and catalysis. Atomic layer deposition (ALD) of ZnO on flat substrates is an industrially applied and well-known process. Various studies describe the growth of ZnO layers on flat substrates. However, the growth characteristics and reaction mechanisms of atomic layer deposition of ZnO on mesoporous powders have not been well studied. This study investigates the ZnO ALD process based on diethylzinc (DEZn) and water with silica powder as substrate. In-situ thermogravimetric analysis gives direct access to the growth rates and reaction mechanisms of this process. Ex-situ analytics, e.g., N2 sorption analysis, XRD, XRF, HRTEM, and STEM-EDX mapping, confirm deposition of homogenous and thin films of ZnO on SiO2. In summary, this study offers new insights into the fundamentals of an ALD process on high surface area powders.

Highlights

ZnO with its unique electronic and optical properties is truly a multi-functional material with applications in optoelectronics [1], sensors [2], photovoltaics [3], and catalysis [4]
The interaction between Cu and ZnO leads to an increase in intrinsic activity of Cu-based methanol synthesis catalysts, which is often related to strong metal support interactions [10]
Regarding analysis of Atomic layer deposition (ALD) processes, this study focused on Pt ALD but lacked details regarding ZnO ALD

Summary

Introduction

ZnO with its unique electronic and optical properties is truly a multi-functional material with applications in optoelectronics [1], sensors [2], photovoltaics [3], and catalysis [4]. Yousfi et al [28] studied the growth behavior of ZnO thin films via atomic layer epitaxy using an in-situ quartz crystal microbalance. They showed the effect of temperature (RT to 200 ◦C) and pulse time on ZnO deposition through analysis of nucleation and coalescence effects. In both studies, growth of nanosized ZnO particles on the exoskeleton of the zeolites within just 1–2 ALD cycles was reported Such a low cycle number would not result in formation of nanocrystalline particles, if the involved process was ALD. A thin conformal layer of ZnO was formed on the high surface area silica using varying number of ALD cycles. The ALD process was later scaled up in a fixed bed (~30 mL volume)

Materials and Methods

Atomic Layer Deposition of ZnO on SiO2

Scale up of Atomic Layer Deposition of ZnO on SiO2

Characterization of Materials

In-Situ Thermogravimetry