Spontaneous phase segregation of Sr2NiO3 and SrNi2O3 during SrNiO3 heteroepitaxy

Recent discovery of superconductivity in Nd0.8Sr0.2NiO2 motivates the synthesis of other nickelates for providing insights into the origin of high-temperature superconductivity. However, the synthesis of stoichiometric R1−xSrxNiO3 thin films over a range of x has proven challenging. Moreover, little is known about the structures and properties of the end member SrNiO3. Here, we show that spontaneous phase segregation occurs while depositing SrNiO3 thin films on perovskite oxide substrates by molecular beam epitaxy. Two coexisting oxygen-deficient Ruddlesden-Popper phases, Sr2NiO3 and SrNi2O3, are formed to balance the stoichiometry and stabilize the energetically preferred Ni2+ cation. Our study sheds light on an unusual oxide thin-film nucleation process driven by the instability in perovskite structured SrNiO3 and the tendency of transition metal cations to form their most stable valence (i.e., Ni2+ in this case). The resulting metastable reduced Ruddlesden-Popper structures offer a testbed for further studying emerging phenomena in nickel-based oxides.

Area-Selective Atomic Layer Deposition of Noble Metals: Polymerized Fluorocarbon Layers as Effective Growth Inhibitors

<p>Selective deposition is a powerful self-aligned precision materials processing strategy which can hugely benefit next-generation nanoelectronics, catalysis, and energy conversion/storage fields. Atomic layer deposition (ALD) is showing a significant promise in enabling area-selective deposition using various growth blocking layers including self-assembled monolayers (SAMs) and various polymers. However, these blocking layers are not compatible with energetic co-reactants like ozone and plasma radicals, showing relatively fast degradation and losing their growth inhibition character. In this work, we demonstrate that polymerized fluorocarbon surfaces function as effective growth inhibitors for ALD-grown Pt and Pd films. Besides effectively inhibiting film growth with considerable nucleation delays for, Pt experiments revealed that polymerized CF_x layers are also ozone-compatible. To the best of our knowledge, this is the first demonstration of an AS-ALD process using ozone as co-reactant for noble metals. In our manuscript, we detail our observations of (Pt,Pd) film nucleation evolution and self-aligned deposition experiments on patterned samples. We have performed in-depth chemical and surface characterizations along the nucleation studies and self-aligned patterning experiments.</p>

Area-Selective Atomic Layer Deposition of Noble Metals: Pol-Ymerized Fluorocarbon Layers as Effective Growth Inhibitors

<p>Selective deposition is a powerful self-aligned precision materials processing strategy which can hugely benefit next-generation nanoelectronics, catalysis, and energy conversion/storage fields. Atomic layer deposition (ALD) is showing a significant promise in enabling area-selective deposition using various growth blocking layers including self-assembled monolayers (SAMs) and various polymers. However, these blocking layers are not compatible with energetic co-reactants like ozone and plasma radicals, showing relatively fast degradation and losing their growth inhibition character. In this work, we demonstrate that polymerized fluorocarbon surfaces function as effective growth inhibitors for ALD-grown Pt and Pd films. Besides effectively inhibiting film growth with considerable nucleation delays for, Pt experiments revealed that polymerized CF_x layers are also ozone-compatible. To the best of our knowledge, this is the first demonstration of an AS-ALD process using ozone as co-reactant for noble metals. In our manuscript, we detail our observations of (Pt,Pd) film nucleation evolution and self-aligned deposition experiments on patterned samples. We have performed in-depth chemical and surface characterizations along the nucleation studies and self-aligned patterning experiments.</p>

Area-Selective Atomic Layer Deposition of Noble Metals: Polymerized Fluorocarbon Layers as Effective Growth Inhibitors

<p>Selective deposition is a powerful self-aligned precision materials processing strategy which can hugely benefit next-generation nanoelectronics, catalysis, and energy conversion/storage fields. Atomic layer deposition (ALD) is showing a significant promise in enabling area-selective deposition using various growth blocking layers including self-assembled monolayers (SAMs) and various polymers. However, these blocking layers are not compatible with energetic co-reactants like ozone and plasma radicals, showing relatively fast degradation and losing their growth inhibition character. In this work, we demonstrate that polymerized fluorocarbon surfaces function as effective growth inhibitors for ALD-grown Pt and Pd films. Besides effectively inhibiting film growth with considerable nucleation delays for, Pt experiments revealed that polymerized CF_x layers are also ozone-compatible. To the best of our knowledge, this is the first demonstration of an AS-ALD process using ozone as co-reactant for noble metals. In our manuscript, we detail our observations of (Pt,Pd) film nucleation evolution and self-aligned deposition experiments on patterned samples. We have performed in-depth chemical and surface characterizations along the nucleation studies and self-aligned patterning experiments.</p>

Area-Selective Atomic Layer Deposition of Noble Metals: Polymerized Fluorocarbon Layers as Effective Growth Inhibitors

<p>Selective deposition is a powerful self-aligned precision materials processing strategy which can hugely benefit next-generation nanoelectronics, catalysis, and energy conversion/storage fields. Atomic layer deposition (ALD) is showing a significant promise in enabling area-selective deposition using various growth blocking layers including self-assembled monolayers (SAMs) and various polymers. However, these blocking layers are not compatible with energetic co-reactants like ozone and plasma radicals, showing relatively fast degradation and losing their growth inhibition character. In this work, we demonstrate that polymerized fluorocarbon surfaces function as effective growth inhibitors for ALD-grown Pt and Pd films. Besides effectively inhibiting film growth with considerable nucleation delays for, Pt experiments revealed that polymerized CF_x layers are also ozone-compatible. To the best of our knowledge, this is the first demonstration of an AS-ALD process using ozone as co-reactant for noble metals. In our manuscript, we detail our observations of (Pt,Pd) film nucleation evolution and self-aligned deposition experiments on patterned samples. We have performed in-depth chemical and surface characterizations along the nucleation studies and self-aligned patterning experiments.</p>

Fractal simulation of thin film nucleation growth process using a diffusion-limited aggregation model

In order to study the initial nucleation and growth process of the films, a two-dimensional (2D) DLA model was established, and fractal dimension was calculated by sandbox method. Compared with the experimental results, the model can well characterize the morphology of nucleation and growth in the initial stage of film growth. In addition to the number of particles and deposition probability involved in other studies, the size of substrate and the location of central particles are also considered in this work. The growth morphology, fractal dimension and the number of simulated steps are presented in this paper.

Nucleation, Growth and Evolution of Hydroxyapatite Films on Calcite

ABSTRACTMarble, a non-porous stone composed of calcite, is subject to acid rain dissolution due to its relatively high dissolution rate. With the goal of preventing such damage, we have investigated the deposition of films of relatively insoluble hydroxyapatite (HAP) on marble. This paper investigates the factors that affect the nucleation and growth kinetics of HAP on marble. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate (DAP) salt was reacted with marble, alone and with cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP films on the mineral surface. Film nucleation, growth and metastable phase evolution were studied, using techniques such as scanning electron microscopy (SEM) and grazing incidence X-ray diffraction (GID). The onset of nucleation, and the growth rate of the film, increased with cationic (calcium) and anionic (carbonate) precursor additions. The calcium and phosphate precursors also influenced metastable phase formation, introducing a new phase.