Ling Zhang

In this work, Ba_0.6Sr_0.4TiO₃ (BST) films were deposited on Si(100) and Pt(111)/Ti/SiO₂/Si(100) substrates using the pulsed laser deposition (PLD) technique. The effects of TiO₂ buffer layer thickness and preparation temperature on the microstructure and electrical properties of BST films were studied in detail. We intensively investigated the influence of the TiO₂ buffer layer on the microstructure of BST films by using X-ray diffraction and scanning electron microscopy. We found that anatase crystalline TiO₂ buffer layers within 15 nm thicknesses could significantly change the BST films from an irregular orientation to the (111) preferential orientation. The TiO₂ anatase layers could promote the growth of BST film grains for obtaining minimal stress and low lattice distortion, increase the nucleation density, and improve its surface morphology, resulting in higher dielectric constant and resistance voltage, and lower dielectric loss and leakage current density. The dielectric constant, dielectric loss, and dielectric tunability of the BST devices with 8 nm thick TiO₂ anatase buffer layers at 1 MHz were 856.5, 0.017, and 64.3%, respectively. The achieved high dielectric tunability indicates BST with TiO₂ anatase buffer layers as one of the encouraging candidates for RF and microwave tunable applications at room temperature.

In recent years, researchers have placed great importance on the use of silicon (Si)-related materials as efficient light sources for the purpose of realizing Si-based monolithic optoelectronic integration. Previous works were mostly focused on Si nanostructured materials, and, so far, exciting results from Si-based compounds are still lacking. In this paper, we have systematically demonstrated the high photoluminescence external quantum efficiency (PL EQE) and internal quantum efficiency (PL IQE) of amorphous silicon oxynitride (a-SiN_xO_y) systems. Within an integration sphere, we directly measured the PL EQE values of a-SiN_xO_y, which ranged from approximately 2% to 10% in the visible range at room temperature. Then, we calculated the related PL IQE through temperature-dependent PL measurements. The obtained PL IQE values (~84% at 480 nm emission peak wavelength) were very high compared with those of reported Si-based luminescent thin films. We also calculated the temperature-dependent PL EQE values of a-SiN_xO_y systems, and discussed the related PL mechanisms.

Nowadays, the emerging photoelectrochemical (PEC) bioanalysis has drawn intensive interest due to its numerous merits. As one of its core elements, functional nanostructured materials play a crucial role during the construction of PEC biosensors, which can not only be employed as transducers but also act as signal probes. Although both chemical composition and morphology control of nanostructured materials contribute to the excellent analytical performance of PEC bioassay, surveys addressing nanostructures with different dimensionality have rarely been reported. In this review, according to classification based on dimensionality, zero-dimensional, one-dimensional, two-dimensional, and three-dimensional nanostructures used in PEC bioanalysis are evaluated, with an emphasis on the effect of morphology on the detection performances. Furthermore, using the illustration of recent works, related novel PEC biosensing patterns with promising applications are also discussed. Finally, the current challenges and some future perspectives in this field are addressed based on our opinions.