Growth Mechanism Of Thin Films Research Articles

Multivariate growth analysis on D019-phase Mn3Ga kagome-based topological antiferromagnets.

The combination of antiferromagnetism and topological properties in Mn3X (X = Sn, Ge,Ga) offers a unique platform to explore novel spin-dependent phenomena and develop innovative spintronic devices. Here, we have systematically investigated the phase transition of Mn3Ga thin films on SiO2(001)/Si substrates under various growth parameters such as seeding layer structure, annealing conditions, and film thickness. The relatively thick Mn3Ga films grown with Ru seeding exhibit a variety of polycrystalline hexagonal phases, including (002), and (201). The addition of a Ta layer to the conventional Ru seeding layer promotes the formation of nearly single-crystal antiferromagnetic Mn3Ga(002) phase from the relatively thin Mn3Ga films after annealing at 773 K. The investigation of the growth mechanism of Mn3Ga polycrystalline thin films provides a reference strategy for exploring Mn-based antiferromagnetic spintronic devices.&#xD.

Growth mechanism of Ge2Sb2Te5 thin films by atomic layer deposition supercycles of GeTe and SbTe

The film with a composition close to Ge2Sb2Te5 was fabricated by the supercycle atomic layer deposition (ALD) of GeTe and SbTe, followed by tellurization annealing. Supercycle processes are widely used for thin film deposition of multicomponent materials and often exhibit non-ideal growth behavior. Since only in situ analysis can reveal the substrate-dependent growth behavior, we used in situ quartz crystal microbalance (QCM) to study the growth mechanism during ALD supercycle processes at 85 °C. GeTe grown on SbTe was more Te-deficient than continuously grown GeTe film. As a result, more Te-deficient Ge-Sb-Te films were formed than expected. By annealing in a Te ambient at 250 °C, the Te-deficient Ge-Sb-Te film was converted to the Ge0.23Sb0.23Te0.54 close to Ge2Sb2Te5 film, which had a high density equivalent to 95 % of the FCC structure of Ge2Sb2Te5. The film showed excellent conformality and uniform composition in a trench pattern, suggesting a uniform crystallization temperature of 118 °C at all locations.

Growth Conditions and Interfacial Misfit Array in SnTe (111) Films Grown on InP (111)A Substrates by Molecular Beam Epitaxy.

Tin telluride (SnTe) is an IV-VI semiconductor with a topological crystalline insulator band structure, high thermoelectric performance, and in-plane ferroelectricity. Despite its many applications, there has been little work focused on understanding the growth mechanisms of SnTe thin films. In this manuscript, we investigate the molecular beam epitaxy synthesis of SnTe (111) thin films on InP (111)A substrates. We explore the effect of substrate temperature, Te/Sn flux ratio, and growth rate on the film quality. Using a substrate temperature of 340 °C, a Te/Sn flux ratio of 3, and a growth rate of 0.48 Å/s, fully coalesced and single crystalline SnTe (111) epitaxial layers with X-ray rocking curve full-width-at-half-maxima of 0.09° and root-mean-square surface roughness as low as 0.2 nm have been obtained. Despite the 7.5% lattice mismatch between the SnTe (111) film and the InP (111)A substrate, reciprocal space mapping indicates that the 15 nm SnTe layer is fully relaxed. We show that a periodic interfacial misfit (IMF) dislocation array forms at the SnTe/InP heterointerface, where each IMF dislocation is separated by 14 InP lattice sites/13 SnTe lattice sites, providing rapid strain relaxation and yielding the high quality SnTe layer. This is the first report of an IMF array forming in a rock-salt on zinc-blende material system and at an IV-VI on III-V heterointerface, and highlights the potential for SnTe as a buffer layer for epitaxial telluride film growth. This work represents an important milestone in enabling the heterointegration between IV-VI and III-V semiconductors to create multifunctional devices.

Optimizing Crystal Orientation and Defect Mitigation in Antimony Selenide Thin-Film Solar Cells through Buffer Layer Energy Band Adjustment.

Antimony selenide (Sb2Se3) has sparked significant interest in high-efficiency photovoltaic applications due to its advantageous material and optoelectronic properties. In recent years, there has been considerable development in this area. Nonetheless, defects and suboptimal [hk0] crystal orientation expressively limit further device efficiency enhancement. This study used Zinc (Zn) to adjust the interfacial energy band and strengthen carrier transport. For the first time, it is discovered that the diffusion of Zn in the cadmium sulfide (CdS) buffer layer can affect the crystalline orientation of the Sb2Se3 thin films in the superstrate structure. The effect of Zn diffusion on the morphology of Sb2Se3 thin films with CdxZn1-xS buffer layer has been investigated in detail. Additionally, Zn doping promotes forming Sb2Se3 thin films with the desired [hk1] orientation, resulting in denser and larger grain sizes which will eventually regulate the defect density. Finally, based on the energy band structure and high-quality Sb2Se3 thin films, this study achieves a champion power conversion efficiency (PCE) of 8.76%, with a VOC of 458mV, a JSC of 28.13mA cm-2, and an FF of 67.85%. Overall, this study explores the growth mechanism of Sb2Se3 thin films, which can lead to further improvements in the efficiency of Sb2Se3 solar cells.

The growth mechanism and properties of Bi2212 thin films on miscut substrates by sol-gel method

A sol-gel methodology is employed to prepare Bi2212 thin films on single crystal LaAlO3 miscut substrates with nominal tilt angles of 0°, 5°, 10°, and 15°. The study focuses on examining the phase purity, crystal structure, surface morphology, microstructure, and properties of these thin films. Experimental results indicate that the growth of Bi2212 thin films on miscut substrates proceeds through the step-flow mode using the sol-gel method. Higher tilt angles lead to an increase in the conventional resistivity of Bi2212 thin films. Tilted Bi2212 thin films exhibit a typical transverse Seebeck effect when comparing the resistivity in different directions. Notably, the Seebeck coefficient difference reaches 12 V/K when the substrate tilt angle is set at 15°. Meanwhile, tilted Bi2212 thin films consistently exhibit outstanding superconducting transition temperature (Tc) while demonstrating lower critical current density (Jc) values. These findings offer valuable insights for the development of Bi2212 high temperature superconducting thin films (HTSFs) in thermoelectric and superconductive devices, serving as a reference point for achieving optimal film characteristics.

Effect of He diluted plasma on the deposition of flexible low-temperature polycrystalline silicon thin film

The growth of a low-temperature polycrystalline silicon (LTPS) thin film on a flexible polyethylene terephthalate (PET) substrate under the assistance of helium plasma has been examined in detail in this study. By utilizing the plasma enhanced chemical vapor deposition method, LTPS thin films are directly deposited on a PET substrate at a relatively low temperature (80 °C), and the variations in the morphology, structure, and electrical property of the samples with He flow are systematically characterized by performing a series of tests. The results show that the purely helium-diluted silane plasma has the function of inducing crystallization and fabricating the c-Si network. After optimizing the He flow rate to 600 SCCM, the LTPS thin film with the largest average grain size of ∼204.7 nm can be obtained, while the maximum dark conductivity (4.16 × 10−5 S/cm) is also achieved. Finally, a detailed discussion is presented to illustrate the growth mechanism of the LTPS thin film in He plasma.

Reaction Dynamics of C(NH2)3SnI3 Formation from Vacuum-Deposited C(NH2)3I and SnI2 Bilayer Thin Films Investigated by In Situ Infrared Multiple-Angle Incidence-Resolved Spectroscopy.

Understanding the formation process of organic-inorganic halide perovskite (OIHP) thin films is important for the fabrication of high-quality thin films, which, in turn, are crucial for achieving high-performance devices. To address this challenge, we developed an in situ system of infrared multiple-angle incidence-resolved spectroscopy (IR-MAIRS) combined with a vacuum deposition system. "Orientation-free" isotropic spectra constructed from IR-MAIRS spectra enable us to perform quantitative analysis of the formation process of C(NH2)3SnI3 (GASnI3) thin films from unreacted C(NH2)3I (guanidine hydroiodide (GAI))/SnI2 bilayer structures predeposited in a vacuum. The analysis of the dependence of the GASnI3 formation rate on the reaction temperature using the Avrami model has revealed that a diffusion-controlled reaction process of GAI and SnI2 governs the formation kinetics. The present study points to the usefulness of in situ IR-MAIRS analysis in understanding the growth mechanisms of vacuum-deposited OIHP thin films and hence the potential to accelerate the development of vacuum processes for the fabrication of high-quality OIHP thin films.

Exploring the growth mechanism of CuSbSe2 thin film prepared by electrodeposition

Exploring the growth mechanism of CuSbSe2 thin film prepared by electrodeposition

A process study of high-quality Zn(O,S) thin-film fabrication for thin-film solar cells

Abstract The Zn(O,S) thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se2 (CIGS) thin-film solar cell due to its advantages of optical responses in the short-wavelength region and adjustable bandgap. In this paper, the thin-film growth mechanism and process optimization of Zn(O,S) films fabricated using the chemical bath deposition method are systematically investigated. The thickness and quality of Zn(O,S) films were found to be strongly affected by the concentration variation of the precursor chemicals. It was also revealed that different surface morphologies of Zn(O,S) films would appear if the reaction time were changed and, subsequently, the optimum reaction time was defined. The film-growth curve suggested that the growth rate varied linearly with the deposition temperature and some defects appeared when the temperature was too high. In addition, to further improve the film quality, an effective post-treatment approach was proposed and the experimental results showed that the microstructure of the Zn(O,S) thin film was improved by an ammonia etching process followed by an annealing process. For comparison purposes, both Zn(O,S)-based and CdS-based devices were fabricated and characterized. The device with a Zn(O,S)-CIGS solar cell after post-treatment showed near conversion efficiency comparable to that of the device with the CdS-CIGS cell.

Reaction mechanism and film properties of the atomic layer deposition of ZrO2 thin films with a heteroleptic CpZr(N(CH3)2)3 precursor

The surface reaction of a heteroleptic precursor in the atomic layer deposition (ALD) of ZrO2 has been investigated using atomically thin films for scaled-down semiconductor devices. Heteroleptic precursors have been widely used in ALD. Because different ligands in heteroleptic precursors have different reaction pathways, understanding the surface reaction is crucial. In this study, we investigate the growth mechanisms of thin films using a CpZr(N(CH3)2)3 precursor with different reactants, such as H2O and O2 plasma. Chemical composition, surface roughness, film density, and microstructures were analyzed through electron microscopy and X-ray techniques together with quantum chemical calculations to elucidate the ZrO2 growth mechanism. The results showed that the reaction pathway of Zr–Cp ligand exchange with surface hydroxyl groups is less favorable than the Zr–N(CH3)2 reaction pathway. Furthermore, H2O molecules showed less effective oxidation reactions with Cp ligands than with alkyl amide ligands. In contrast, all the ligands were completely removed, resulting in negligible impurity incorporation, as revealed via X-ray photoelectron spectroscopy, when O2 plasma was used, leading to an improved leakage current (30-fold reduction). We believe that these findings on the surface reactions of heteroleptic ALD precursors will be helpful for developing future scaled-down semiconductor devices.

Structure and Optical Property Prediction of 2D Plasmonic Photonic Crystals Fabricated by Shadow Sphere Lithography

Shadow sphere lithography (SSL) is a powerful and large-scale fabrication method to produce two-dimensional (2D) plasmonic photonic crystals and three-dimensional metamaterials. Practically, one of the biggest challenges for SSL-based fabrications is that it is hard to accurately predict the physical properties of the fabricated nanostructures if the structures were only modeled by the geometric shadowing effect. A Monte Carlo (MC) simulation is developed to show that the dynamic shadowing effect due to the accumulation of materials on the template as well as the thin-film growth mechanism plays a key role in determining the structure details. For a one-to-three step-based SSL fabrication, the nanostructures predicted by MC match very well with those produced experimentally, and the plasmonic properties predicted by these MC-simulated structures are also consistent with the features obtained experimentally, both qualitative and semi-quantitative. This study indicates a possible solution to use MC simulation and numerical calculation to guide the design of the plasmonic photonic crystals and metamaterials based on SSL for optic applications.

The Growth Mechanism of a Conductive MOF Thin Film in Spray-based Layer-by-layer Liquid Phase Epitaxy.

The layer-by-layer liquid-phase epitaxy (LBL-LPE) method is widely used in preparing metal-organic framework (MOF) thin films with the merits of controlling thickness and out-of-plane orientation for superior performances in applications. The LBL-LPE growth mechanism related to the grain boundary, structure defect, and orientation is critical but very challenging to study. In this work, a novel "in-plane self-limiting and self-repairing" thin-film growth mechanism is demonstrated by the combination study of the grain boundary, structure defect, and orientation of Cu3 (HHTP)2 -xC thin film via microscopic analysis techniques and electrical measurements. This mechanism results a desired high-quality MOF thin film with preferred in-plane orientations at its bottom for the first time and is very helpful for optimizing the LBL-LPE method, understanding the growth cycle-dependent properties of MOF thin film, and inspiring the investigations of the biomimetic self-repairing materials.

The Growth Mechanism of a Conductive MOF Thin Film in Spray‐based Layer‐by‐layer Liquid Phase Epitaxy

AbstractThe layer‐by‐layer liquid‐phase epitaxy (LBL‐LPE) method is widely used in preparing metal–organic framework (MOF) thin films with the merits of controlling thickness and out‐of‐plane orientation for superior performances in applications. The LBL‐LPE growth mechanism related to the grain boundary, structure defect, and orientation is critical but very challenging to study. In this work, a novel “in‐plane self‐limiting and self‐repairing” thin‐film growth mechanism is demonstrated by the combination study of the grain boundary, structure defect, and orientation of Cu3(HHTP)2‐xC thin film via microscopic analysis techniques and electrical measurements. This mechanism results a desired high‐quality MOF thin film with preferred in‐plane orientations at its bottom for the first time and is very helpful for optimizing the LBL‐LPE method, understanding the growth cycle‐dependent properties of MOF thin film, and inspiring the investigations of the biomimetic self‐repairing materials.

An in-depth analysis of nucleation and growth mechanism of CdS thin film synthesized by chemical bath deposition (CBD) technique

The aim of this study is to acquire a deeper understanding of the response mechanism that is associated with the formation of CdS thin films. We presented an effective and new hybrid sensitisation technique, which involved the 1-step linker between the related chemical bath deposition (CBD) process and the traditional doping method during CBD for synthesising high-quality, CdS thin films. The mechanism for the combined synthesis of the films is also describes. CdS films were electrostatically bonded to soda-lime glass, causing the formation of the intermediate complexes [Cd(NH3)4]2+, which aided in the collision of these complexes with a soda-lime glass slide. In the one-step fabrication technique, 3-Mercaptopropionic Acid (MPA) was employed as a second source of sulphur ions and a linker molecule. Optical studies showed that the bandgap ranged between (2.26–2.52) eV. CdS + MPA films exhibited a uniform distribution of spherical molecules based on their morphological properties. After annealing, this approach significantly altered the electrical characteristics of CdS films. The CdS + MPA films displayed the highest carrier concentration whereas the CdS + Ag + MPA films exhibited the lowest resistivity, with a jump of 3 orders of magnitude.

One-Stage Hydrothermal Growth and Characterization of Epitaxial LaMnO3 Films on SrTiO3 Substrate.

Epitaxial LaMnO3 thin films were grown on SrTiO3 substrate using a one-stage hydrothermal route from La(NO3)3, MnCl2 and KMnO4 in an aqueous solution of 10 M KOH at 340 °C. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) indicate full coverage of LaMnO3 on the substrate. X-ray diffraction in the symmetric ω/2θ mode suggests the film has an out-of-plane preferred orientation along the [001] direction of the substrate. The LaMnO3 epitaxial thin film growth mechanism is proposed based on the analysis of the atomic sharp interface formed between LaMnO3 and the SrTiO3 substrate, as seen by aberration−corrected scanning transmission electron microscopy (AC−STEM) imaging in combination with electronic energy loss spectroscopy (EELS). Compared with the conventional vapor deposition methods, the one-stage hydrothermal route opens up a new way to fabricate complex oxide epitaxial heterostructures.

Growth Mechanisms of TaN Thin Films Produced by DC Magnetron Sputtering on 304 Steel Substrates and Their Influence on the Corrosion Resistance

In this work, thin films of TaN were synthesized on 304 steel substrates using the reactive DC sputtering technique from a tantalum target in a nitrogen/argon atmosphere. All synthesis parameters such as gas ratio, pressure, gas flow, and substrate distance, among others, were fixed except the applied power of the source for different deposited coatings. The effect of the target power on the formation of the resulting phases and the microstructural and morphological characteristics was studied using XRD and AFM techniques, respectively, in order to understand the growth mechanisms. Phase, line profile, texture, and residual stress analysis were carried out from the X-ray diffraction patterns obtained. Atomic force microscopy analysis allowed us to obtain values for surface grain size and roughness which were related to growth mechanisms in accordance with XRD results. Results obtained showed a strong correlation between the growth energy with the crystallinity of the samples and the formation of the possible phases since the increase in the growth power caused the samples to evolve from an amorphous structure to a cubic monocrystalline structure. For all produced samples, the δ-TaN phase was observed despite the low N2 content used in the process (since for low N2 content it was expected to be possible to obtain films with α-Ta or hexagonal ε-TaN crystalline structure). In order to determine the corrosion resistance of the coatings, electrochemical impedance spectroscopy and polarization resistance were employed in the Tafel region. The results obtained through this evaluation showed a direct relationship between the power used and the improvement of the properties against corrosion for specific grain size values.

Annealing Engineering in the Growth of Perovskite Grains

Perovskite solar cells (PSCs) are a promising and fast-growing type of photovoltaic cell due to their low cost and high conversion efficiency. The high efficiency of PSCs is closely related to the quality of the photosensitive layer, and the high-quality light absorbing layer depends on the growth condition of the crystals. In the formation of high-quality crystals, annealing is an indispensable and crucial part, which serves to evaporate the solvent and drive the crystallization of the film. Various annealing methods have different effects on the promotion of the film growth process owing to the way they work. Here, this review will present a discussion of the growth puzzles and quality of perovskite crystals under different driving forces, and then explain the relationship between the annealing driving force and crystal growth. We divided the main current annealing methods into physical and chemical annealing, which has never been summarized before. The main annealing methods currently reported for crystal growth are summarized to visualize the impact of annealing design strategies on photovoltaic performance, while the growth mechanisms of thin films under multiple annealing methods are also discussed. Finally, we suggest future perspectives and trends in the industrial fabrication of PSCs in the future. The review promises industrial manufacturing of annealed PSCs. The review is expected to facilitate the industrial fabrication of PSCs.

Investigation of the growth mechanism and crystallographic structures of GaSb dots nucleation layer and GaSb thin film grown on Si(001) substrate by molecular beam epitaxy

We investigated the growth mechanism and crystallographic structures of GaSb dots as a nucleation layer and GaSb thin films grown on a Si(001) substrate by molecular beam epitaxy using atomic force microscopy and transmission electron microscopy (TEM). The surface morphology of the 100-nm-thick GaSb with GaSb dots drastically changed from that without them. As the GaSb dots gradually grew in size, the coalescence between the adjacent dots was repeated and the space between them was filled, thereby changing the growth mode of GaSb to two-dimensional growth and forming domain structures with terrace surfaces. The high-resolution TEM images and fast Fourier transform patterns revealed that the lattice-mismatched strain in the epitaxial GaSb thin film was almost completely relieved. Because some adatoms were rotated by 60° on the {111} facets and formed a monolayer with a wurtzite structure as a stacking fault in the initial growth stage, twinned GaSb with an inclination of 54.7° from the (001) plane was formed in addition to epitaxial GaSb. The lattice-mismatched strain was nearly relieved in the vicinity of the GaSb/Si interface because of the multiple periodic 90° and 60° misfit dislocation arrays. The formation of GaSb dots, which acted as crystal nuclei and induced periodic misfit dislocation arrays, was useful for the epitaxial growth of GaSb thin films on a Si(001) substrate—a result that will be advantageous for growing high-quality GaSb thin films, with flatter and fewer crystal defects, on a Si(001) substrate in future.

Fabrication of TiVO4 photoelectrode for photoelectrochemical application.

Photoelectrochemical (PEC) water splitting is one of the promising, environmentally friendly, carbon emission-free strategies for the cost-effective production of hydrogen. The interest in developing effective approaches for solar-to-hydrogen production with stable and visible light active semiconductors directed many researchers to develop stable and efficient materials. For the first time, a nanostructured TiVO4 photoanode was fabricated at a substrate temperature of 250 °C and further annealed at 600 °C using the spray pyrolysis technique and it obtained an optical band gap of ∼2.18 eV. The photoanode underwent photoelectrochemical testing, where it exhibited a high photocurrent density of 0.080 mA cm-2 at 1.23 V (vs. reversible hydrogen electrode), which can be stable up to 110 min. Further, various physicochemical characterizations were employed to understand the phase purity and thin film growth mechanism. A systematic substrate and annealed temperatures were monitored during the fabrication process. The transmission electron microscopy (TEM) studies revealed agglomeration of TiVO4 nanoparticles with an average size of ∼100 nm accompanying dendritic orientation at the outer edge. This study envisages the design and development of a novel photocatalyst for water splitting under visible light irradiation, an ideal route to a cost-effective, large-scale, sustainable route for hydrogen production.

Control of the Cu morphology on Ru-passivated and Ru-doped TaN surfaces - promoting growth of 2D conducting copper for CMOS interconnects.

Prolonging the lifetime of Cu as a level 1 and level 2 interconnect metal in future nanoelectronic devices is a significant challenge as device dimensions continue to shrink and device structures become more complex. At nanoscale dimensions Cu exhibits high resistivity which prevents its functioning as a conducting wire and prefers to form non-conducting 3D islands. Given that changing from Cu to an alternative metal is challenging, we are investigating new materials that combine properties of diffusion barriers and seed liners to reduce the thickness of this layer and to promote successful electroplating of Cu to facilitate the coating of high-aspect ratio interconnect vias and to allow for optimal electrical conductance. In this study we propose new combined barrier/liner materials based on modifying the surface layer of the TaN barrier through Ru incorporation. Simulating a model Cu29 structure at 0 K and through finite temperature ab initio molecular dynamics on these surfaces allows us to demonstrate how the Ru content can control copper wetting, adhesion and thermal stability properties. Activation energies for atom migrations onto a nucleating copper island allow insight into the growth mechanism of a Cu thin-film. Using this understanding allows us to tailor the Ru content on TaN to control the final morphology of the Cu film. These Ru-modified TaN films can be deposited by atomic layer deposition, allowing for fine control over the film thickness and composition.