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As one of the two-dimensional (2-D) transition metal dichalcogenides, atomically thin molybdenum disulfide (MoS 2 ) has attracted significant attention and research interests for micro and nanoelectronic applications. Significant efforts have been made to develop different approaches in order to obtain atomic layer MoS 2 , such as exfoliation, chemical synthesis, and physical or chemical vapor deposition (CVD) processes. In this paper, we report a hydrogen-free and promoter-free CVD growth to synthesize large-area MoS 2 atomic layers. A variety of techniques including optical microscopy (OM), atomic force microscopy (AFM), photoluminescence (PL) mapping, Raman and x-ray photoelectron spectroscopy (XPS), high resolution electron microscopy (HREM) and scanning transmission electron microscopy (STEM) were applied to characterize the film quality, uniformity and layer numbers. High quality centimeter-sized MoS 2 atomic layers were demonstrated, which form a foundation to develop wafer-sized material platform for device fabrication and production. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we report on a novel surface micromachining process technology for the fabrication of microelectromechanical systems in SiC. Single-crystal SiC suspended microstructures were fabricated using a dopant-selective photoelectrochemical etching process, which allows for undercutting the p-SiC layer by rapid lateral etching of the underlying n-SiC substrate. The selective etching was achieved by applying a bias which employs the different flat-band potentials of n-SiC and p-SiC in the KOH solution. Single-crystal SiC MEMS developed in this study fully exploits the superior mechanical and biocompatible properties of SiC and has the capability of monolithic integration with electron devices and circuits, and therefore, is promising for sensing and actuating operations in biomedical, high-temperature and harsh environments. [ABSTRACT FROM AUTHOR]

Abstract: SiO2 encapsulation layer was studied for aluminum (Al) and phosphorus (P) implant activation anneal in 4H-SiC. Both Al- and P+ implantation were carried out at 650°C followed by activation anneal at 1400°C to 1500°C. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and four-point-probe (FPP) measurements were performed to examine surface stoichiometry, roughness, and sheet resistance of the implanted SiC regions. The effect of using SiO2 encapsulation layer for Al implant activation on the performance of 4H-SiC p-i-n diodes with both p-type active region and JTE region formed by Al implantation was also investigated. Forward and reverse characteristics including saturation current density J 0 , ideality factor η, reverser leakage current density J L and threshold breakdown voltage V BR have been extracted. The results show that SiO2 encapsulation effectively protects the SiC surface during high temperature implant activation for both Al- and P+. [ABSTRACT FROM AUTHOR]

Highlights • Y 2 O 3 /Al 2 O 3 stacking films on p-type 4H-SiC were studied for the first time. • High-k Y 2 O 3 /Al 2 O 3 provides thicker film with equivalent capacitance. • Y 2 O 3 /Al 2 O 3 exploits the high breakdown strength of 4H-SiC in MOSFET. • Post deposition annealing affects properties of Y 2 O 3 /Al 2 O 3. Abstract In this paper, the effect of post deposition annealing (PDA) on the chemical, structural, and electrical properties of the high-k Y 2 O 3 /Al 2 O 3 stacking dielectric on p-type 4H-SiC were studied. High-k dielectric provides a physically thicker film with equivalent capacitance, therefore better exploits the high breakdown strength of 4H-SiC in its MOSFET devices. The Y 2 O 3 /Al 2 O 3 stacking films were deposited using RF magnetron sputtering, with PDA in Ar ambient at 400 °C, 600 °C, 800 °C and 1000 °C. X-ray diffraction (XRD) and angle resolved X-ray photoelectron spectroscopy (XPS) results show that an Al 5 O 12 Y 3 crystal layer was formed in between Y 2 O 3 and Al 2 O 3 films after annealing above 600 °C. High resolution transmission electron microscope (HRTEM) was used to investigate the atomic structure and measure the thickness of each layer. Charges and dielectric strength of the stacking films were characterized by high frequency capacitance-voltage (C-V) and current-voltage (I-V) measurements. The lower charge density and higher dielectric strength were found after PDA at 800 °C and 1000 °C. [ABSTRACT FROM AUTHOR]

In this letter, the potential of single crystalline 4H-polytype silicon carbide (4H-SiC) based microelectromechanical structures as resistance thermometer for high temperature sensing were explored. A dopant-selective photoelectrochemical etching process was applied to release the sensing element – suspended microstructures on 4H-SiC substrate. Residual stress and stress gradient in the microstructure before and after release was examined by micro-Raman spectroscopy. Electrical resistance of the suspended microstructures at different temperatures were characterized and analyzed by a temperature-dependent electron mobility model. [ABSTRACT FROM AUTHOR]

• Not only surface nano-pit impacts leakage current but also dislocation itself. • Threading edge dislocation dominates leakage current in 4H-SiC Schottky diodes. • Surface potential of threading edge dislocation is higher than screw dislocation. • Threading dislocation changes the band-structure of Schottky barrier by stain-field. This study compared the influences of threading edge and screw dislocation (TED and TSD) defects and their work functions on electrical property of leakage current statistically through the reverse current–voltage characteristics of dozens of pieces of 4H-SiC Schottky barrier diodes (SBDs). The experimental results indicated that TEDs correlated strongly more than TSDs to the leakage current in 4H-SiC SBDs under the soft-breakdown regime. Furthermore, Kelvin probe force microscopy revealed that the work function at TED site was about 15 meV lower than that at TSD site. We proposed a possible mechanism based on band-structure near the Schottky barrier, which illustrated that TED site possesses the larger degree of band bending and therefore increases the tunneling transmission probability in contrast to TSD site. [ABSTRACT FROM AUTHOR]