Surface Engineering Of Substrates Research Articles

Surface Engineering of Substrates for Chemical Vapor Deposition Growth of Graphene and Applications in Electronic and Spintronic Devices

Controllable synthesis of large-scale and high-quality graphene film is a basis for development of electronic and spintronic devices. Chemical vapor deposition (CVD) has been considered as a potential method for the industrialized preparation of high-quality graphene. The substrate in CVD is used to support graphene and even help graphene grow. Different substrates may lead to different graphene growth results. Therefore, it is of great importance to select appropriate substrates and growth strategies. In addition, the performance demands of advanced device also urgently require high-quality CVD-derived graphene supports. In this review, we summarize the current advances in surface engineering on substrates for CVD growth of graphene. Surface engineering involves anisotropic disordered, anisotropic ordered, and isotropic homogeneous surfaces of catalytic substrates, and surfaces of insulating substrates. Meanwhile, we describe how to use different surface engineering techniques to control the orientation of graphene domains, grow large-area single-crystal graphene domains, and regulate graphene layers. This information will provide a reference for the effective selection of substrates. Moreover, we review the current progress of graphene in the fields of charge and spin transport, demonstrating that graphene has broad prospects in the next generation of communications and storage. Finally, the opportunities and challenges in the controllable CVD-derived preparation of graphene and its application are discussed.

Impact of PECVD-prepared interfacial Si and SiGe layers on epitaxial Si films grown by PECVD (200 °C) and APCVD (1130 °C)

The homoepitaxy of Si is particularly interesting for the purpose of kerfless wafer production, for example in the photovoltaic domain. Substrate surface engineering is a key step prior to epitaxial growth, which will affect the quality of the epitaxial layer and its detachment for layer transfer. In this work, we propose two plasma-based surface engineering methods including the deposition of a bilayer homoepitaxial interface and a SiGe heteroepitaxial interface. Their impact on the crystalline quality of epitaxial Si layers grown both by plasma-enhanced chemical vapor deposition (PECVD) at 200 °C and by atmospheric pressure chemical vapor deposition (APCVD) at 1130 °C are explored. Stacking faults are observed in epitaxial Si layers with an ultra-thin epitaxial Si interface layer. For surface engineering method based on the addition of an interfacial heteroepitaxial SiGe layer, a higher interfacial hydrogen content and a better bulk epitaxial Si quality are observed in comparison with interfacial homoepitaxial Si layer.

Enhancement of electrical performance of atomic layer deposited SnO films via substrate surface engineering

Substrate surface engineering improves structural and electrical properties of ALD-grown SnO films.

Modified Zinc Oxide Nanoparticles for Corrosion Resistance Applications

Atmospheric corrosion is a big threat to the steel structures. This is because it compromises its structural integrity, aesthetic aspects and overall efficiency. An attempt has been made to counteract this through surface engineering of substrates including glass and steel by using modified zinc oxide nanoparticles to increase hydrophobicity. The synthesis of zinc oxide nanoparticles is carried out by using sol-gel method, thereafter these particles were modified by using stearic acid; a fatty acid. The zinc oxide nanoparticles were characterized by using X-ray diffraction analysis (XRD) which confirms the presence of hexagonal wurtzite structure. Moreover, the Scanning Electron microscopy (SEM) reveals the hexagonal wurtzite morphology of as prepared nanoparticles. Fourier transform infrared spectroscopy (FTIR) confirms the grafting of stearic acid on the surface of ZnO in bidentate form. The water Contact Angle obtained by using sessile drop method gives a statistical value of 140o which is of great interest due to higher water repellency and lower surface contact area. Finally, corrosion test was carried out on the coated steel substrate by means of conventional corrosion testing technique and it is observed that the coated sample decays three times slower than that of its bare steel counterpart.

Modified Zinc Oxide Nanoparticles for Corrosion Resistance Applications

Atmospheric corrosion is a big threat to the steel structures. This is because it compromises its structural integrity, aesthetic aspects and overall efficiency. An attempt has been made to counteract this through surface engineering of substrates including glass and steel by using modified zinc oxide nanoparticles to increase hydrophobicity. The synthesis of zinc oxide nanoparticles is carried out by using sol-gel method, thereafter these particles were modified by using stearic acid; a fatty acid. The zinc oxide nanoparticles were characterized by using X-ray diffraction analysis (XRD) which confirms the presence of hexagonal wurtzite structure. Moreover, the Scanning Electron microscopy (SEM) reveals the hexagonal wurtzite morphology of as prepared nanoparticles. Fourier transform infrared spectroscopy (FTIR) confirms the grafting of stearic acid on the surface of ZnO in bidentate form. The water Contact Angle obtained by using sessile drop method gives a statistical value of 140o which is of great interest due to higher water repellency and lower surface contact area. Finally, corrosion test was carried out on the coated steel substrate by means of conventional corrosion testing technique and it is observed that the coated sample decays three times slower than that of its bare steel counterpart.

Substrate surface engineering for high-quality silicon/aluminum superconducting resonators

Quantum bits (qubits) with long coherence times are an important element for the implementation of medium- and large-scale quantum computers. In the case of superconducting planar qubits, understanding and improving qubits’ quality can be achieved by studying superconducting planar resonators. In this paper, we fabricate and characterize coplanar waveguide resonators made from aluminum thin films deposited on silicon substrates. We perform three different substrate surface treatments prior to aluminum deposition: one chemical treatment based on a hydrofluoric acid clean; one physical treatment consisting of a thermal annealing at 880 °C in high vacuum; and one combined treatment comprising both the chemical and the physical treatments. The aim of these treatments is to remove the two-level state (TLS) defects hosted by the native oxides residing at the various samples’ interfaces. We first characterize the fabricated samples through cross-sectional tunneling electron microscopy, acquiring electron energy loss spectroscopy maps of the samples’ cross sections. These measurements show that both the chemical and the physical treatments almost entirely remove native silicon oxide from the substrate surface and that their combination results in the cleanest interface. Additionally, we analyze the effects of the various substrate treatments on the roughness of the silicon surface by means of atomic force microscopy surface morphology mapping. We then study the quality of the resonators by means of microwave measurements in the ‘quantum regime’, i.e., at a temperature T ∼ 10 mK and at a mean microwave photon number . In this regime, we find that both surface treatments independently improve the resonator’s intrinsic quality factor by ≈172%. The highest quality factor is obtained for the combined treatment, Qi ≈ 0.82 million, corresponding to an improvement by ≈256%. Finally, we find that the TLS quality factor averaged over a time period of 3 h is ∼3 million at , indicating that substrate surface engineering can potentially reduce the TLS loss below other losses such as quasiparticle loss and flux noise.

Selective-area growth and controlled substrate coupling of transition metal dichalcogenides

Developing a means for true bottom-up, selective-area growth of two-dimensional (2D) materials on device-ready substrates will enable synthesis in regions only where they are needed. Here, we demonstrate seed-free, site-specific nucleation of transition metal dichalcogenides (TMDs) with precise control over lateral growth by utilizing an ultra-thin polymeric surface functionalization capable of precluding nucleation and growth. This polymer functional layer (PFL) is derived from conventional photoresists and lithographic processing, and is compatible with multiple growth techniques, precursors (metal organics, solid-source) and TMDs. Additionally, we demonstrate that the substrate can play a major role in TMD transport properties. With proper TMD/substrate decoupling, top-gated field-effect transistors (FETs) fabricated with selectively-grown monolayer MoS2 channels are competitive with current reported MoS2 FETs. The work presented here demonstrates that substrate surface engineering is key to realizing precisely located and geometrically-defined 2D layers via unseeded chemical vapor deposition techniques.

Influence of metallic substrate surface engineering on peel resistance of adhesively bonded polymer film

The peel resistance of adhesively bonded polymer films to a stainless steel sheet substrate (SSSS) with different engineered surface characteristics was examined in two different loading directions and for two different peel speeds. The SSSS was laminated with two thin polymeric adherends using two different pressure-sensitive adhesives. The SSSS surface was altered by grinding and knurling techniques before lamination and the effects of surface alterations on peel resistance were compared with peel resistance of the adherend from as-received SSSS with a bright annealed surface condition. For ground surface, an increase in adherend peel resistance was observed and the increase was attributed to increase in contact area between the adhesive and SSSS surface. For knurled surfaces which involved deeper and less frequent grooves, however, a decrease in peel resistance was observed. This was attributed to a more complex stress state at the peel front in the SSSS groove region during peeling. An increase in peel speed enhanced the peel resistance from both ground and knurled surfaces.

Fluorinated Graphene for Promoting Neuro‐Induction of Stem Cells

Surface engineering of substrates offers the possibility of controlling the physiological functions of cells at the molecular level. Fluorinated graphene promotes the differentiation of MSCs towards neuronal lineages. Cell alignment using printed polydimethylsiloxane channel arrays on fluorinated graphene further enhances the neuro-induction of MSCs even in the absence of chemical inducers.

Fiber-shaped all-solid state dye sensitized solar cell with remarkably enhanced performance via substrate surface engineering and TiO2 film modification

Highly efficient, flexible and large-size fiber-shaped solid state dye-sensitized solar cells (ss-DSSCs) were designed and fabricated by employment of annealed Ti wire as substrate and the subsequent polymer-templated TiO2 nanocrystalline film as photoanode. The work function measurement showed that the passivation titanium oxide layer, formed on the surface of the Ti wire substrate, reduced the Schottky barrier present at the anode interface, i.e. enhanced the charge collecting property of the substrates. The photovoltaic performance and EIS (electrical impedance spectroscopy) results reveal that the solar cells' performance can be further improved by adding PS (polystyrene) emulsion into the P25 colloid to act as a template, with the consequence that the pore filling of the electrolyte and the electron life time (τ) of TiO2 layers increase. All these aspects contribute to a high solar-to-electric conversion efficiency of 1.38%, which was much higher than the previous reported result (0.06%).

Substrate Surface Engineering for Functional Ceramic Thin Film Growth

A concept is introduced, using oxide substrates for functional ceramic thin film deposition beyond their usual application as chemical inert, lattice-matched support for the films. The substrates are applied as a functional element in order to controllably modify the atom arrangement and the growth mode of cuprate superconductors and colossal magnetoresistance materials. These materials have been chosen as prototypes of the general class of perovskite functional ceramics. One example studied is the use of epitaxial strain to adjust the relative positions of cations and anions in the film and thus modify their physical properties. The other makes use of vicinal cut SrTiO3 which enables the fabrication of regular nanoscale step and terrace structures. In YBa2Cu3O7 − x thin films grown on vicinal cut SrTiO3 single crystals a regular array of antiphase boundaries is generated causing an anisotropic enhancement of flux-line pinning. In the case of La-Ca-Mn-O thin films grown on vicinal cut substrates it could be demonstrated that magnetic in-plane anisotropy is achieved.

Substrate surface engineering for tailoring properties of functional ceramic thin films

Using oxide substrates for functional ceramic thin film deposition beyond their usual application as chemical inert, lattice-matched support for the films represents a novel concept in ceramic thin film research. The substrates are applied as a functional element in order to controllably modify the atom arrangement and the growth mode of ceramic prototype materials such as cuprate superconductors and colossal magnetoresistance manganites. One example is the use of epitaxial strain to adjust the relative positions of cations and anions in the film and thus modify their physical properties. The other makes use of vicinal cut SrTiO3 which enables the fabrication of regular nanoscale step and terrace structures. In YBa2Cu3O7-x thin films grown on vicinal cut SrTiO3 single crystals a regular array of antiphase boundaries is generated causing an anisotropic enhancement of flux-line pinning. In the case of La-Ca-Mn-O thin films grown on vicinal cut substrates it could be demonstrated that magnetic in-plane anisotropy is achieved.

Supercritical fluids—a novel approach to magnetic media production?: An introduction to supercritical fluid technologies and how they might be applied to deposition/impregnation of metallics, magnetic inks and protective lubrication

The production of magnetic media requires a combination of substrate surface engineering, magnetic ink or metal deposition, and a thin-film high-performance lubricant to protect the surface and read–write head from abrasive wear. The lubricant, such as a perfluoroether oil or derivative, is normally applied via a dilute solution in fluorocarbon 113 solvent which is now known as a banned ozone depleter. The search for alternatives has led to developments in water-borne coatings but water can be an expensive and troublesome solvent. A novel means of delivering magnetic inks to a surface may be via supercritical carbon dioxide or xenon spray systems. Fluorinated and silicone oils are soluble in supercritical CO 2 and can also be applied by this residue-free technique. Supercritical fluids offer the opportunity to deposit/impregnate metals into surfaces via organometallics. Could this replace the future magnetic media production?