Enhancement of the thermoelectric performance of (BiSb)2Te3 films by single target sputtering

In this study, (BiSb) 2Te3 films were deposited onto a glass substrate at 300 °C using radio frequency (RF) sputtering at various growth conditions. The effects of RF power, chamber gas pressure, and annealing temperature on the thermoelectric properties of the deposited films were investigated. An increase in the annealing temperature was found to enhance both the deposition rate and grain size. After optimizing the growth conditions and applying further annealing treatment, thin films grown at higher RF power exhibited higher electrical conductivity, attributable to an increase in carrier concentration. Additionally, films grown under 37.5 W RF power demonstrated an enhancement in the Seebeck coefficient, leading to a maximum power factor. The deposition chamber's base pressure was 10−6 mbar, and the optimal thermoelectric performance was achieved in the film grown under 0.04 mbar Ar+ partial pressure

Quantum defects in two-dimensional van der Waals materials

Quantum defects in solid materials, such as nitrogen-vacancy color centers in diamond, have been extensively studied and successfully demonstrated as single photon emitters and potential qubits for quantum computers. However, a major challenge has always been positioning these quantum defects near the sample surface for measuring or sensing purposes. The emergence of quantum defects in two-dimensional (2D) van der Waals (vdW) materials open up new opportunities for overcoming these limitations. These materials possess unique properties, including vdW interlayer coupling and clean surfaces without unsaturated dangling bonds, which provide greater advantages for manufacturing multi-qubit systems. In this review, we present the research progress on quantum defects in 2D vdW materials, covering quantum guidelines for spin defects in solid state, the latest demonstrations of quantum defects, the unique methods and techniques for generating and modulating defects in 2D vdW materials.</p

Diamond with nitrogen: states, control, and applications

The burgeoning multi-field applications of diamond concurrently bring up a foremost consideration associated with nitrogen. Ubiquitous nitrogen in both natural and artificial diamond in most cases as disruptive impurity is undesirable for diamond material properties, eg deterioration in electrical performance. However, the feat of this most common element-nitrogen, can change diamond growth evolution, endow diamond fancy colors and even give quantum technology a solid boost. This perspective reviews the understanding and progress of nitrogen in diamond including natural occurring gemstones and their synthetic counterparts formed by high temperature high pressure (HPHT) and chemical vapor deposition (CVD) methods. The review paper covers a variety of topics ranging from the basis of physical state of nitrogen and its related defects as well as the resulting effects in diamond (including nitrogen termination on diamond surface), to precise control of nitrogen incorporation associated with selective post-treatments and finally to the practical utilization. Among the multitudinous potential nitrogen related centers, the nitrogen-vacancy (NV) defects in diamond have attracted particular interest and are still ceaselessly drawing extensive attentions for quantum frontiers advance.</p

Enhanced Performance of Solar‐Blind UV Photodetector Based on β‐Ga₂O₃ Nanowires Grown by a Magnetron Sputtering

The development of simple and highly controllable fabrication methods for the β‐Ga2O3, especially for the nanowire structure, has been a challenge. The slanted Ga2O3 nanowires are favorable for increasing the optical contact area and improving photon flux through nanoparticle scattering, leading to an increase in the photogenerated carrier yield. Herein, obliquely oriented and uniformly distributed β‐Ga2O3 nanowires are fabricated on Si substrates by a radio frequency magnetron sputtering using the strategy of Au nanoparticles as an intermediate catalyst. By depositing Ti and Au electrodes, the metal–semiconductor–metal Ga2O3‐based photodetectors are fabricated with a simple structure. Remarkably, the photodetector based on the β‐Ga2O3 nanowires outperforms the one based on the β‐Ga2O3 film, demonstrating higher responsivity and an exceptional photocurrent‐to‐dark current ratio (Iphoto/Idark) of 1.43 × 104 @5 V. This work presents a promising approach to enhance the utilization of incident light and maximize the generation of photoinduced carriers in the Ga2O3‐based photodetectors

A new thermoelectric Ag8SiSe6 Argyrodite for room temperature application: its cooling conditions sensitivity of thermoelectric performance

The present commercial thermoelectrics like (BiSb)2Te3 compounds include expensive and toxic Te element, which hampers a large-scale thermoelectric application near room temperature. Ag8SiSe6 argyrodite compound, as a green and low cost thermoelectric material, is potential candidate for BiSbTe compounds. In this work, Ag8SiSe6 compounds were synthesized through a traditional melting process combined with a hot pressing densification, marking the first systematic investigation of their thermoelectric properties linking to different post-treatments. By designing the cooling rates of the ingots, a substantial improvement in the power factor has been attained, particularly in the sample quenched in water, due to a marked reduction in resistivity. To our knowledge, although a pure Ag8SiSe6 phase cannot be prepared by possible available fabrication method up to now the current methods, a high-performance thermoelectric material has been fabricated through the integration of ball milling treatment with the quenched ingot, achieving a peak ZT value of approximately 0.71 at 398 K.</p

Evolutionary features of subsurface defects of single crystal diamond after dynamic friction polishing

Due to the fatigue and continuous energy input during high-speed dynamic friction polishing (DFP), the diamond crystal beneath the polished surface (roughness 50 nm) and even preferential crystal cleavage with the non-diamond phase (distributing at the position in micrometers range).</p

Evolutionary features of subsurface defects of single crystal diamond after dynamic friction polishing

Due to the fatigue and continuous energy input during high-speed dynamic friction polishing (DFP), the diamond crystal beneath the polished surface (roughness 50 nm) and even preferential crystal cleavage with the non-diamond phase (distributing at the position in micrometers range).</p

Morphology-dependent antibacterial properties of diamond coatings

Microorganisms promoted corrosion has caused significant loss to marine engineering and the antibacterial coatings have served as a solution that has gained attention. In this study, the chemical vapour deposition technique has been employed to grow three different types of diamond coatings, namely, ultrananocrystalline diamond (UNCD), nanocrystalline diamond (NCD), and microcrystalline diamond (MCD) coatings. The evolution of associated surface morphology and the surface functional groups of the grown coatings have demonstrated antibacterial activity in seawater environments. It is found that different ratio of sp3/sp2 carbon bonds on the diamond coatings influences their surface property (hydrophobic/hydrophilic), which changes the anti-adhesion behaviour of diamond coatings against bacteria. This plays a critical role in determining the antibacterial property of the developed coatings. The results show that the diamond coatings arising from the deposition process kill the bacteria via a combination of the mechanical effects and the functional groups on the surface of UNCD, NCD, and MCD coatings, respectively. These antibacterial coatings are effective to both Gram-negative bacteria (E. coli) and Gram-positive bacteria (B. subtilis) for 1–6 h of incubation time. When the contact duration is prolonged to 6 h or over, the MCD coatings begin to reduce the bacteria colonies drastically and enhance the bacteriostatic rate for both E. coli and B. subtilis.</p

Higher-order resonance of single-crystal diamond cantilever sensors toward high f‧Q products

MEMS resonant sensing devices require both HF (f) and low dissipation or high quality factor (Q) to ensure high sensitivity and high speed. In this study, we investigate the resonance properties and energy loss in the first three resonance modes, resulting in a significant increase in f‧Q product at higher orders. The third order resonance exhibits an approximately 15-fold increase in f‧Q product, while the Q factor remains nearly constant. Consequently, we achieved an ultrahigh f‧Q product exceeding 1012 Hz by higher-order resonances in single-crystal diamond cantilevers.</p