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Indium tin oxide (ITO) film, which is the most commonly used transparent conductive film (TCF), has traditionally been believed to be transparent in the visible spectrum but to reflect infrared (IR) light beyond the plasma wavelength (λp). However, our theoretical analysis challenges this notion by demonstrating that an ultrathin ITO TCF that is thinner than the light's penetration depth can overcome the transmission barrier at λp. To validate the theoretical modeling, we have successfully fabricated ultrathin ITO films that, despite having λp ≈ 1 μm, remain transparent from 400 nm to 20 μm. This represents the broadest transparency range ever reported for any In2O3-based TCF. The 10-nm-thick ITO TCFs have high visible transmittance (91.0% at 550 nm), low resistivity (5 × 10−4 Ω cm), and good IR transmittance (averaging 60% over 1.35–18.35 μm). Their IR transparency facilitates radiative cooling of the underlying circuitry. When an operational resistor is enclosed by commercial ITO TCFs that are 140 nm thick, its temperature increases. However, using 10-nm-thick ITO TCFs instead of the commercial ones can completely avoid this temperature rise. Moreover, attaching a silver grid to a 10-nm-thick ITO TCF can reduce the effective sheet resistance to ∼10 Ω/□ at the expense of only ∼3% transmittance. This development paves the way for large-scale applications that require low sheet resistance and far-IR transparency. [ABSTRACT FROM AUTHOR]

Oxygen sensors, using organic-inorganic and all-inorganic lead halide perovskites, have demonstrated huge advantages in operating temperature, responding time, and reversing oxygen content detection. Nevertheless, the toxicity and instability issues hinder their wide application. In this work, for the first time, we report a sensitive fluorescence oxygen detector based on lead-free double perovskite Cs 2 AgBiBr 6 thin film. The sensor has a remarkable performance in terms of fast response time of ≈56 s, recovery time of ≈91 s, and a relatively low limit of detection (LOD) of 150 ppm. More importantly, the unencapsulated sensor still exhibits an obvious response at low oxygen concentrations after two-week storage in ambient, and the device also exhibits good humidity, light, and thermal stability. Consequently, the lead-free double perovskite (Cs 2 AgBiBr 6) will be promising environmentally friendly material in developing reversible, sensitive, high-efficiency, and stable perovskite oxygen sensors. [ABSTRACT FROM AUTHOR]

Abstract The improvement of comprehensive properties including hardness, toughness, wear, and corrosion resistance in the transition-metal carbides/nitrides (TMC(N)) films, especially avoiding the trade-off between the hardness and toughness, is strongly required for various applications. Herein, we provide a new strategy, by activating solid-state dewetting during layered deposition, to accomplish the self-assembly of ordered TaC@Ta core–shell-like nanocomposite film consisting of TaC nanocrystallines encapsulated with thin pseudocrystal Ta tissues (∼1.5 nm). The novel core−shell-like structure can simultaneously achieve superhardness (∼45.1 GPa) mainly dominated by the Orowan strengthening mechanism and high toughness attributed to the indenter-induced phase transformation from the pseudocrystal to body-centered cubic α-Ta, together with drastically enhanced wear and corrosion resistance. Furthermore, thin pseudocrystal Ta encapsulated layer (∼1.5 nm) in the TaC@Ta core–shell-like structure helps for promoting the formation of lubricious TaO x Magnéli phase during sliding, thereby further dropping the coefficient of friction relative to TaC monolayer. Apparently, solid-state dewetting may provide a new route to construct ordered TMC(N)@TM core–shell-like nanocomposite structure capable of combining superhardness, high toughness, low friction, and superior wear and corrosion resistance. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Increasing demands for robust hydrophobic or hydrophilic surfaces in harsh conditions such as erosion, abrasion and high temperature, have stimulated the development of intrinsically hydrophobic or hydrophilic ceramics (or metals). Despite tremendous efforts, realizing robust highly hydrophobic or hydrophilic ceramics surfaces using a simple method remains a great challenge. In this letter, we report that HfN x -Ag films with two different existing forms of Ag: (1) Solute Ag and (II) Precipitate Ag, were deposited using co-sputtering system by setting deposition temperature at room temperature (RT) and 400 °C, respectively, further achieving highly hydrophobic (water contact angle (WCA) ∼ 120°) or hydrophilic (WCA ∼ 55°) surfaces by controlling the content of solute Ag or precipitate Ag. Solute Ag provides the hydrophobic Ag 2 O groups with coordinative saturation though surface self-oxidation, which inhibits hydrogen bonding with interfacial water molecules, whereas hydrophilic precipitate Ag acts as Lewis acid, which interacts strongly with water. [ABSTRACT FROM AUTHOR]

Although surface roughening of films holds an important role in determining the final surface morphologies and properties, how to control it is not yet well explored. Here, we report that the surface roughening of hafnium nitride films varies significantly as a stoichiometry-driven phase transformation takes place. Through a combination of surface morphological measurements and simulations, we demonstrate that the variation of roughening mechanisms arises from the changes in diffusion behavior during growth. This study shows that the phase transformation can induce surface roughening transition, thus providing a new handle in controlling the morphologies and physical properties of thin films. [ABSTRACT FROM AUTHOR]

A stoichiometry-driven phase transition from rocksalt to “nitrogen-rich” structure exists in group-IVB transition metal nitride films. As this phase transition is critical in controlling the film properties it has attracted numerous studies. However, researchers are still divided with regard to the structural identity of this “nitrogen-rich” phase, not to mention detailed exploration of the phase transition mechanisms. In this study, we confirmed that the “nitrogen-rich” phase in hafnium nitride (HfN x ) films had a cubic Th 3 P 4 structure of space group symmetry of I- 43 d (220), namely c -Hf 3 N 4 . The confirmation was obtained by combining the first-principle calculations with a series of experiments: Selected Area Electron Diffraction, High Resolution Transmission Electron Microscopy, Raman, Gracing Incident X-ray Diffraction and X-ray Photoelectron Spectroscopy. The mechanisms of the phase transition were elucidated through calculations on enthalpy of formation ( EOF ). The experimental results agree well with the theoretical calculations. We conclude that with increasing nitrogen, phase transition takes place from rocksalt ( δ -HfN) to c -Hf 3 N 4 through three stages of structural evolution: δ -HfN (containing Hf vacancies) → mixture of ( δ -HfN + c -Hf 3 N 4 ) → c -Hf 3 N 4 . The driving force of the phase transition is energy minimization. The three stages of structural evolution are explained by comparing the EOF of the δ -HfN and c -Hf 3 N 4 phases. As the phase transition takes place, the hafnium nitride film morphs from a conductive and opaque metal into an insulating and transparent semiconductor. [ABSTRACT FROM AUTHOR]

The changes of flow stress in voids-free, and HV and FV films are related to the dislocation density in the strain processes. Following the decrease of relative stacking faults, the decrease of flow stress in FV films is faster than that in HV film. Nanocrystalline ultrathin metallic thin films have various applications for which mechanical properties and durability are important, such as electrodes and electrical interconnects. We investigated the effect of voids on mechanical behavior of thin nanocrystalline gold films using molecular dynamics. Different kinds of voids were considered. We found that the nature and geometry of the void was important for the mechanical properties in this model ductile material. It was found that in the half voids films the flow stress decreased following the decrease of mass density with a linear relation. For the full voids films, the strain–stress curve was different from that of voids-free film and half voids films. The plastic deformation could be activated with smaller amount of dislocations. Following the strain increase over the strain of ultimate tensile strength, the flow stress decreased. This implied that the voids which penetrated through the films would weaken the ductility of films. The deformation main mechanism was grain boundaries sliding with voids coalescence. On the contrary, if the void depth was less than the thickness of film, the ductility of film wasn't influenced apparently, though the ultimate tensile strength decreased with the increase of voids size and decrease of mass density. [ABSTRACT FROM AUTHOR]