Functional Perovskites by Atomic Layer Deposition – An Overview

Abstract

properties in thin film complex oxides and their heterostructures is still in its infancy.Functional perovskite oxide thin films have traditionally been deposited by physical, high temperature techniques, such as molecular beam epitaxy (MBE) and pulsed laser deposition (PLD). While these methods can provide films of very high structural quality, they do not offer deposition of conformal film on complex structures while maintaining control of stoichiometry. Chemical deposition techniques were long thought unsuitable for deposition of complex systems with high structural quality. This has changed dramatically over the last two decades. One of the most important techniques to emerge in this area has been atomic layer deposition (ALD).In this short review we aim to summarize the perovskite and ABO 3 -oxides, down to the ilmenite structure, that have been deposited using the ALD technique. The review includes work done over the last 20 years, and covers all oxide perovskites with ferromagnetic, piezoelectric and ferroelectric functionality known to have been deposited by ALD ( Table 1). The origin of the properties in these specific structures is briefly discussed, followed by a complete listing of the known systems. Perovskite heterostructures with new properties and combinations of properties are brought up, before thoughts on possible future work in the field concludes the paper. Why Atomic Layer Deposition?The ALD technique was pioneered independently in both Russia and Finland during the 1960s and 70s, and its history was thoroughly described by Puurunen in 2014. [4] The technique has been comprehensively discussed in several review papers over the last years. The first commercial application was to deposit zinc sulfide, used for electroluminescent display panels. The number of materials with known deposition routes was very limited for the first 20 years, before it exploded in the 1990s and still continues to grow. At the time of the review written by Miikkulainen et al. in 2013, binary oxides of most of the natural elements had been reported, as well as many nitrides, sulfides and fluorides (Figure 2). [5] As the community has embraced the possibility of growing epitaxial films of high chemical and structural quality, systems that are even more complex have been deposited, including materials with ternary, quaternary and even quinary compositions.The advantages and drawbacks of ALD as a thin film deposition technique have been reviewed several times the The last 20 years have seen a massive increase in reports on complex oxides with functional properties synthesized by atomic layer deposition (ALD). Many of these compounds have perovskite or perovskite-related structures, and exhibit a range of electric and magnetic properties. This short review summarizes the current status of functional perovskites and ABO 3 compounds down to the ilmenite structure prepared by ALD, focusing on ferromagnetism and ferro-and piezoelectricity. All perovskite-related compounds known to have been deposited by ALD down to the ilmeni...

Surface Tuning of Solid Oxide Fuel Cell Cathode by Atomic Layer Deposition

“…[15] Considering the microporous structure of the SOFC cathode formed to maximize the surface area and facilitate the transport of oxygen gas, the process of depositing a uniform thin film, such as ALD, can be a suitable solution for cathode surface tuning. [24][25][26][27][28] However, to our best knowledge, no research has been conducted on SOFC cathode surface tuning using a complex oxide fabricated by ALD and its catalytic activity. However, the surface tuning of the SOFC cathode by ALD reported so far has been mostly limited to simple binary oxides (ZrO 2 , [16,17] SrO, [18] CeO x , [18] Al 2 O 3 , [19] La 2 O 3 , [20] Fe 2 O 3 , [20] and CoO x [21] ) for the purpose of studying the surface reaction mechanism of the cathode.…”

Formation of BiFeO3 from a Binary Oxide Superlattice Grown by Atomic Layer Deposition

“…[8][9][10][11][12][13] AlthoughA LD is primarily used for the growth of binary oxide films and coatings, in the last years the integrationo fe pitaxialp erovskite thin films on semiconductor substrates has been reported, [14] making this synthesis methoda ppealing for large-scale deposition of complex functional oxides such as ferroelectric BaTiO 3 or BFO. [15] The synthesis of ferroelectrically switchable BFO utilizing ALD was demonstrated for both epitaxial andp olycrystalline films. [16][17][18][19][20][21][22][23][24][25] Direct evidenceo ff erroelectricity with ar emnant polarization of % 2 mCcm À2 was first reported for a1 0-nm-thick film grown on aL aNiO 3 (001)/SiO 2 /Si(001) substrate.…”

Atomic layer deposition of perovskites—Part 1: Fundamentals of nucleation and growth

“…Thus, detailed knowledge of the growth mechanism and precursor interaction is required for controlled growth and tunable functionalities. The functionality can be controlled by different parameters such as composition of the films, concentration of point defects, lattice strain or crystal structure, allowing us to explore new applicational possibilities in terms of novel and high‐performing electronic devices . Thus, the study of perovskites using ALD is a unique combination, providing us with a possibility to tweak many parameters eventually leading to interesting and unique properties in the thin film regime.…”

“…The functionality can be controlled by different parameters such as composition of the films, concentration of point defects, 13 lattice strain 14 or crystal structure, allowing us to explore new applicational possibilities in terms of novel and high-performing electronic devices. 15 Thus, the study of perovskites using ALD is a unique combination, providing us with a possibility to tweak many parameters eventually leading to interesting and unique properties in the thin film regime. Whereas this may bring a paradigm shift in material technology, the understanding of the process and structure developing during growth is yet limited.…”