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The authors report the enhancement of the magnetic sensitivity of single-crystal diamond (SCD) MEMS magnetic sensor, which is composed of a SCD cantilever integrated with a magneto-strictive Galfenol (FeGa) thin film. To improve the magnetic sensing properties from room temperature to high temperatures, different interlayers of Ti film, WC film, and WC/Ti film are inserted between the SCD cantilevers and the FeGa thin films in the SCD-MEMS magnetic sensors. The thermal-stability of the microstructures, phase structures, and magnetic properties of the FeGa thin films are greatly enhanced by these interlayers. The FeGa thin films within the FeGa/SCD, FeGa/Ti/SCD, FeGa/WC/SCD, and FeGa/Ti/WC/SCD structures maintain high thermal-stability in surface morphologies, roughness, phase structures, and magnetic properties under the annealing temperature up to 573 K, 773 K, 573 K, and 673 K, respectively. The magnetic sensor with the FeGa/SCD structure has the weakest magnetic sensitivity of 1.96 Hz/mT @573 K and the FeGa/WC/Ti/SCD structure hosts the highest magnetic sensitivity of 75.40 Hz/mT @673 K. The present work provides a strategy to tailor the magnetic sensing properties of SCD MEMS for the applications under extreme conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

The coupling of single crystal diamond (SCD) micro-electromechanical systems (MEMS) through with a functional hetero-material provides the strategy to develop diamond MEMS sensors. Here a noncontact magnetic sensor based on SCD MEMS resonance system functionalized with a boron-doped FeGa (FeGaB) thin film owning excellent magneto-strictive properties on diamond is demonstrated to improve the magnetic sensitivity. The amorphous FeGaB thin film is beneficial for high magnetic sensing performance. The FeGaB/Ti/SCD MEMS magnetic sensor exhibits magnetic sensitivity of as high as 152.1 Hz/mT, which is over four times of those of FeGa/Ti/SCD MEMS magnetic sensors. The derivative of the Young's modulus change with magnetic field (dE/dH) reaches a maximum value of 4.5 GPa/mT at 1.77 mT. By tailoring the magnetic properties with impurity dopant, one can markedly improve the sensitivity of the diamond MEMS magnetic sensitivity toward satisfying the figure-of-merits of ultra-high sensitivity, low noise level and high-reliability magnetic field operation. Image 1 [ABSTRACT FROM AUTHOR]

The authors report on the marked improvement of the quality factor (Q-factor) of single crystal diamond (SCD) nanoelectromechanical system (NEMS) resonators through annealing in oxygen ambient. The SCD NEMS resonators were fabricated by ion implantation assisted technique. The resonance frequency followed well the inverse power law relationship with the length of the cantilevers despite of the annealing. It was observed that there was little modification in the resonance frequency and Q-factor at 430 °C, while an obvious red-shift in the resonance frequency occurred at 500 °C. Meanwhile, a marked improvement in the Q-factor from around 3500 to 7000 was observed at 500 °C. The frequency red shift is due to the etching of diamond with a rate of 0.4–0.5 nm/h at 500 °C. The analysis of the energy dissipation discloses that the surface effect dominates the energy loss mechanism for the SCD NEMS resonator. The improvement of the Q-factor is thus attributed to the reduction of the surface defects in SCD NEMS. [ABSTRACT FROM AUTHOR]

Single-crystal diamond (SCD) is a promising material for micro-electromechanical system (MEMS) devices to achieve high performance and reliability due to its prominent mechanical and physical properties. However, the application of SCD MEMS has not been practically achieved due to the lack of device concept for SCD MEMS. Here, the SCD MEMS resonator based magnetic sensor is successfully realized with integrating of a large magneto-strictive galfenol film on SCD mechanical resonator with high performance. It is concluded that SCD provides a suitable substrate for galfenol film with excellent magnetic properties. Along with the high-quality factor of the SCD MEMS resonator, a high magnetic field sensitivity of 4.83 Hz/mT and an extremely low detectable force of 2.14 × 10−12 N are achieved. Based on the experimental results, the estimated minimum detectable force, magnetic field and energy reach 1.76 × 10−14 N, 1.42 × 10−10 T and 8.4 × 10−29 J. The successful fabrication of SCD MEMS magnetic sensor provides a promising strategy for broadening the application of SCD MEMS with merits super to other ones, such as nanoscale to microscale spatial resolution, wide-range magnetic field sensing, high sensitivity, high temperature operation, and facile integration with CMOS. Single crystal diamond MEMS cantilever resonator integrating with a large magneto-strictive galfenol film is demonstrated for magnetic sensor. The magnetic sensor shows a high magnetic field sensitivity of 4.83 Hz/mT and an extremely low detectable force of 2.14 × 10−12 N. The current work of successful fabrication of SCD MEMS magnetic sensor provides a promising strategy for broadening the application of SCD MEMS with merits super to other ones, such as nanoscale to microscale spatial resolution, wide-range magnetic field sensing, high sensitivity, high temperature operation, and facile integration with CMOS. Image 1 [ABSTRACT FROM AUTHOR]

Effective heat dissipation of semiconductor devices is crucial for their extended lifespan and operational stability, and the interface of semiconductors provides an effective window for thermal design and management. In this work, we have systematically investigated the effect of the carbon vacancy on the thermal conductivity of diamond and the interface thermal conductance (ITC) of Cu/diamond by using both first-principles calculation and molecular dynamics methods. Although the carbon vacancy leads to a decrease in the thermal conductivity of diamond, a marked increase in ITC from 37.98 MWm−2K−1 to about 177 MWm−2K−1 for diamond (1 1 1) plane and from 78.8 MWm−2K−1 to about 241 MWm−2K−1 for diamond (0 0 1) plane is observed between Cu and diamond with carbon vacancy. The increase of the ITC is mainly due to the anharmonic phonon scattering, revealed by the phonon density of states and phonon participation ratio. Compared to the ITC at Cu/C interface with Vc far from the interface, the Vc in interface region has a more significant effect in enhancing the ITC, which indicate that the effect of Vc on ITC has strong localization characteristics at Cu/C interface. The maximum values of the ITC at the (0 0 1) Cu/C and (1 1 1) Cu/C interfaces with the Vc are about three times and over four times than these at the (0 0 1) Cu/C and (1 1 1) Cu/C interfaces without the Vc, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• A strategy based on single crystal diamond (SCD) micro-electromechanical system (MEMS) to obtain characterization of atomic-scale etching of single crystal diamond in pure H 2 plasma ambient is proposed. • An etching rate of several nm/h (a few carbon atomic layers) is obtained. • The etching of SCD by hydrogen helps the understanding of diamond growth and the stability of SCD. • The measurement technique based on MEMS/NEMS is also potentially useful in corrosion science for other materials etched with other reactive gases or mixtures (not limited to H 2 plasma). It is well known that single crystal diamond (SCD) could be etched in hydrogen plasma ambient. However, the precise characterization of the corrosion behavior of SCD is not well understood. Here, we utilize the shift of single crystal diamond (SCD) cantilever's resonance frequency to characterize the corrosion rate of SCD with (100) oriented surface in hydrogen plasma at the temperatures of 800−900 °C. The etching rate increased from ∼3.3 nm/hour at 800 °C to ∼7 nm/hour at 900 °C. This work helps understanding the stability of diamond for applications from mechanical to electronic devices as well as the dynamic growth of diamond. [ABSTRACT FROM AUTHOR]

A supercritical ethanol (scEtOH) environment, in which sulfur is highly soluble, can lead to safety improvements and cost reductions in the sulfurization process. In this study, the feasibility of the sulfurization process in scEtOH for the preparation of Cu 2 ZnSnS 4 (CZTS) thin films at low temperature was verified with the purpose of creating a sustainable and cost-effective process for fabricating metal-sulfide solar cells. We found that to promote atomic diffusion of sulfur and achieve sulfurization at a low temperature, the presence of defects in the amorphous oxide thin film was preferable. Moreover, in thin film fabricated by sulfurization under ethanol, the crystal size was strongly affected by ethanol density. The grain size increased up to about 1 μm as the ethanol density increased, and grain growth was remarkable, particularly in the high-density conditions of over 3.0 mol/L. Finally, we fabricated a crystalline CZTS thin film, which exhibited structural and optical properties comparable to those of a film fabricated using conventional vapor-phase sulfurization. For the prepared disordered-kesterite CZTS thin film with a Cu-poor and Zn-rich composition, photoluminescence measurements confirmed that the donor or acceptor defects engage in the emission of about 1.24 eV at 5 K, and UV–Vis measurement revealed a bandgap of 1.38 eV at room temperature. [ABSTRACT FROM AUTHOR]

In this study, we fabricated a three-dimensional CuInS 2 solar-cell structure using supercritical fluid deposition and sulfurization, in which p-n junction is formed at the large surface of a nanoporous n-type TiO 2 film filled with a p-type CuInS 2 semiconductor to facilitate the efficient collection of photoinduced electrons and holes. Using the reductive reaction of organometallic precursors dissolved in supercritical fluid at the surface, we successfully and efficiently deposited Cu–In film inside the nanoporous film consisting of TiO 2 nanoparticles with a diameter of a few tens of nanometers. The CuInS 2 film formed following the sulfurization of the Cu–In film exhibited an ideal band gap (1.5 eV) and photoconductivity. The results obtained in this study expand the applicability of supercritical fluid technology to the fabrication of chalcogenide semiconductors inside nanostructured materials and will contribute to the future development of or improvement in various types of energy devices. [ABSTRACT FROM AUTHOR]

The authors proposed a novel α -BN/ h -BN dual-layered dielectric to fabricate AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT). In contrast to the Schottky-HEMT, the gate leakage current was suppressed by more than 6 orders of magnitude at forward voltage of 5V. An atomically smooth interface and low interface state density were obtained, benefiting from the quasi-zero lattice mismatch and the passivation effect of α -BN on AlGaN. Electrical analyses demonstrated that boosted gate drive capability, enhanced output current, and high field effect mobility were realized with inserted BN. The electrical breakdown behaviors of BN were investigated with regard to Frenkel-Poole emission mechanism and Fowler-Nordheim tunneling theory for the low and high electric field regime, respectively. This work rendered BN as a perfect candidate for dielectric insulator used in field-effect transistors. • Novel α -BN/ h -BN dielectric for AlGaN/GaN MIS-HEMT. • Significant gate leakage reduction due to suppression of FP emission and FN tunneling. • Significant drain current enhancement due to mobility improvement. [ABSTRACT FROM AUTHOR]