In this paper, the Fe³⁺ doped rutile phase TiO₂ nanotubes arrays (NTAs) were prepared in a low temperature water-assistant crystallization method. It is noteworthy that the Fe³⁺ doping hardly hinders either the crystallization of rutile TiO₂ NTAs or the highly-ordered nanotubular morphologies. Moreover, Fe³⁺ did not form other compound impurities, which indicated that Fe³⁺ substitute Ti⁴⁺ into the lattice of TiO₂. With the introduction of Fe³⁺, the light absorption range of TiO₂ NTAs extends from the ultraviolet band to the visible light range. Photocatalytic testing results indicate that Fe³⁺ doped TiO₂ NTAs can effectively improve the degradation rate of methyl orange aqueous solution in visible light, and the TiO₂ NTAs with 0.2 mol/L Fe³⁺ doping exhibits the highest photocatalytic degradation efficiency.

Oxygen defects in Hafnium Oxide (HfO₂)-based ferroelectric thin films not only are related to the cause of ferroelectricity but also affect the ferroelectric properties of the thin films. This paper, therefore, focuses on the fabrication of Zr:HfO₂ thin films by RF (Radio Frequency) magnetron sputtering with Zr-doped HfO₂ as the target and examines how oxygen flow impacts the oxygen vacancies and electrical properties thereof. Additionally, TiN thin-film electrodes were prepared by direct current (DC) magnetron reactive sputtering using nitrogen as the reaction gas, the influences of the substrate temperature on the film deposition rate and crystal phase structure were investigated, and the resultant thin-film electrodes with the lowest resistivity were obtained. Furthermore, the ferroelectric hysteresis loop and leakage current density of metal–insulator–metal (MIM) ferroelectric capacitors formed by annealing the 30 nm thick deposited Zr:HfO₂ sandwiched between the top and bottom TiN electrodes were measured. The results demonstrate that varying oxygen flow has a considerable effect on oxygen vacancies and the Zr doping concentration of deposited Zr:HfO₂ ferroelectric thin films. When the oxygen flow is set to 40 sccm (standard cubic centimeters per minute) and an external electric field strength of 2 mV/cm is applied, the remnant polarization reaches 18 μC/cm², with a decrease in the leakage current density of 10^5–6 orders of magnitude.

In this paper, synthetically using refraction, diffraction, and interference effects to achieve free manipulation of the focused optical field, we firstly present a photonic nanojet (PNJ) generated by a micropyramid, which is combined with multilayer thin films. The theory of total internal reflection (TIR) was creatively used to design the base angle of the micropyramid, and the size parameters and material properties of the microstructure were deduced via the expected optical field distribution. The as-designed bilayer micropyramid array was fabricated by using the single-point diamond turning (SPDT) technique, nanoimprint lithography (NIL), and proportional inductively coupled plasma (ICP) etching. After the investigation, the results of optical field measurement were highly consistent with those of the numerical simulation, and they were both within the theoretical calculation range. The bilayer micropyramid array PNJ enhanced the interference effect of incident and scattered fields; thus, the intensity of the focused light field reached 33.8-times that of the initial light, and the range of the focused light field was extended to 10.08$\lambda$. Moreover, the full width at half maximum (FWHM) of the focal spot achieved was 0.6$\lambda$, which was close to the diffraction limit.

HfO₂ thin films were deposited on BK-7 glass substrates using an electron beam evaporation deposition (EBD) technique and then post-treated with argon and oxygen ions at an ion energy ranging from 800 to 1200 eV. The optical properties, laser damage resistance, and surface morphology of the thin films exposed to Ar ions and O₂ ions at various energies were studied. It was found that the two ion post-treatment methods after deposition were effective for improving the LIDT of HfO₂ thin films, but the mechanism for the improvement differs. The dense thin films highly resistant to laser damage can be obtained through Ar ion post-treatment at a certain ion energy. The laser-induced damage threshold (LIDT) of thin films after O₂ ion post-treatment was higher in comparison to those irradiated with Ar ion at the same ion energy.

Double perovskite Cs₂SnI₆ and its doping products (with SnI₂, SnF₂ or organic lithium salts added) have been utilized as p-type hole transport materials for perovskite and dye-sensitized solar cells in many pieces of research, where the mechanism for producing p-type Cs₂SnI₆ is rarely reported. In this paper, the mechanism of forming p-type Li⁺ doped Cs₂SnI₆ was revealed by first-principles simulation. The simulation results show that Li⁺ entered the Cs₂SnI₆ lattice by interstitial doping to form strong interaction between Li⁺ and I⁻, resulting in the splitting of the α spin-orbital of I–p at the top of the valence band, with the intermediate energy levels created and the absorption edge redshifted. The experimental results confirmed that Li⁺ doping neither changed the crystal phase of Cs₂SnI₆, nor introduced impurities. The Hall effect test results of Li⁺ doped Cs₂SnI₆ thin film samples showed that Li⁺ doping transformed Cs₂SnI₆ into a p-type semiconductor, and substantially promoted its carrier mobility (356.6 cm²/Vs), making it an ideal hole transport material.

Hafnium oxide thin films have attracted great attention as promising materials for applications in the field of optical thin films and microelectronic devices. In this paper, hafnium oxide thin films were prepared via DC magnetron sputtering deposition on a quartz substrate. The influence of various negative biases on the structure, morphology, and mechanical and optical properties of the obtained films were also evaluated. XRD results indicated that ($\overline{1}11$)-oriented thin films with a monoclinic phase could be obtained under the non-bias applied conditions. Increasing the negative bias could refine the grain size and inhibit the grain preferred orientation of the thin films. Moreover, the surface quality and mechanical and optical properties of the films could be improved significantly along with the increase in the negative bias and then deteriorated as the negative bias voltage arrived at −50 V. It is evident that the negative bias is an effective modulation means to modify the microstructural, mechanical, and optical properties of the films.