W. J. Zhang

Ultrathin MXene-Micropattern-Based Field-Effect Transistor for Probing Neural Activity.

A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed and utilized as a highly sensitive biosensor. The device is produced with the microcontact printing technique, making use of its unique advantages for easy fabrication. Using the MXene-FET device, label-free probing of small molecules in typical biological environments and fast detection of action potentials in primary neurons is demonstrated.

193nm deep-ultraviolet solar-blind cubic boron nitride based photodetectors

Deep-ultraviolet (DUV) solar-blind photodetectors based on high-quality cubic boron nitride (cBN) films with a metal/semiconductor/metal configuration were fabricated. The design of interdigitated circular electrodes enables high homogeneity of electric field between pads. The DUV photodetectors present a peak responsivity at 180nm with a very sharp cutoff wavelength at 193nm and a visible rejection ratio (180 versus 250nm) of more than four orders of magnitude. The characteristics of the photodetectors present extremely low dark current, high breakdown voltage, and high responsivity, suggesting that cBN films are very promising for DUV sensing.

p-type conduction in arsenic-doped ZnSe nanowires

Reliable p-type conduction was achieved in ZnSe nanowires (NWs) synthesized by introducing Zn3As2 as a dopant source. The crystal structure and orientation of NWs remained unchanged after doping. The electrical and transport properties of As-doped ZnSe NWs were investigated via the characteristics of NW-based field-effect transistors. The origin of p-type conduction in ZnSe NWs is attributed to the formation of substitutional AsSe and AsZn−2VZn complexes. Arsenic atoms were considered to incorporate into ZnSe lattices partly as As–H pairs; therefore postgrowth annealing could improve p-type conduction by dissociating As–H bonds and activating As acceptors.

Heterocrystal and bicrystal structures of ZnS nanowires synthesized by plasma enhanced chemical vapour deposition

ZnS nanowires with heterocrystal and bicrystal structures were successfully synthesized using the DC-plasma chemical vapour deposition (CVD) method. The heterocrystalline ZnS nanowires have the zinc blende (ZB) and wurtzite (WZ) zones aligned alternately in the transverse direction but without an obvious period. The bicrystal ZnS nanowires are composed of two ZB fractions separated by a clear grain boundary along the length. Significantly, the grain boundaries in both the heterocrystal and bicrystal structures are atomically sharp without any visible lattice distortion. The effects of plasma species, ion bombardment, and silicon impurities in the formation of these distinctive structures are discussed. A defect-induced red-shift and broadening of the band-gap emission are revealed in photoluminescence (PL) and cathodoluminescence (CL) measurements.

Bias-assisted etching of polycrystalline diamond films in hydrogen, oxygen, and argon microwave plasmas

Bias-assisted etching of diamond films was performed in a microwave plasma chemical vapor deposition system. Hydrogen, hydrogen/oxygen, and hydrogen/argon mixtures were used as reactant gases. The effects of both the reactant gas compositions and applied substrate bias on the etching rate, surface morphology, and phase variation were investigated by scanning electron microscopy and Raman spectroscopy. The contribution of ions of different reactant gases to the etching of diamond films was discussed.

Diamond and Cubic Boron Nitride: Properties, Growth and Applications

Since their first synthesis, cubic boron nitride (c‐BN) and diamond thin films have triggered a vivid interest in these wide band gap materials for many different applications. Because of superior properties, c‐BN and diamond can be applied in optic, electronic and acoustic for high performances devices. In this discussion, we first describe briefly the properties of c‐BN and diamond and we review both the growth techniques and the progresses achieved in the synthesis of c‐BN and diamond, and in a second part, characteristics of new c‐BN and diamond UV detectors for solar observation are reported. These photo‐detectors present extremely low dark current, high breakdown voltage, high responsivity and stability under UV irradiation. Finally, diamond based acoustic devices and sensors are presented. High frequency acoustic wave devices can be design for high frequency filtering or sensing applications. Diamond/AlN micro‐cantilevers are excellent platform for sensor applications.

High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B4C target in an Ar/N2 gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

Field-Effect Transistors: Ultrathin MXene-Micropattern-Based Field-Effect Transistor for Probing Neural Activity (Adv. Mater. 17/2016).

A field-effect transistor (FET) based on ultrathin Ti3 C2 -MXene micropatterns is developed by C. Zhi, P. Shi, and co-workers, as described on page 3333. The FET can be utilized for label-free probing of small molecules in typical biological environments, e.g., for fast detection of action potentials in primary neurons. This device is produced with a microcontact printing technique, harnessing the unique advantages for easy fabrication.

A flexible object tracking system for planary motion

Object visual tracking and servo is a challenging research topic in the fields of computer vision, pattern recognition and robotics. Usually, people just utilize PTZ for active surveillance tracking. In this work, we combine visual tracking and visual servo to drive a PTZ to cast laser beam on the target object. The demonstrated tracking system is friendly-using and accurate which can be used for object tracking in plane, such as stage lighting effect, video surveillance, etc. Our proposed tracking system features arbitrarily installation, automatic parameters calibration, high efficiency and low coupling. From the point of mathematical modeling, our model outputs exact solution without any accuracy loss.