Soft magnetic robots have attracted tremendous interest owning to their controllability and manoeuvrability, demonstrating great prospects in a number of industrial areas. However, further explorations on the locomotion and corresponding deformation of magnetic robots with complex configurations are still challenging. In the present study, we analyse a series of soft magnetic robots with various geometric shapes under the action of the magnetic field. First, we prepared the matrix material for the robot, that is, the mixture of silicone and magnetic particles. Next, we fabricated a triangular robot whose locomotion speed and warping speed are approximately 1.5 and 9 mm/s, respectively. We then surveyed the generalised types of robots with other shapes, where the movement, grabbing, closure and flipping behaviours were fully demonstrated. The experiments show that the arching speed and grabbing speed of the cross-shaped robot are around 4.8 and 3.5 mm/s, the crawling speed of the pentagram-shaped robot is 3.5 mm/s, the pentahedron-shaped robot can finish its closure motion in 1 s and the arch-shaped robot can flip forward and backward in 0.5 s. The numerical simulation based on the finite element method has been compared with the experimental results, and they are in excellent agreement. The results are beneficial to engineer soft robots under the multi-fields, which can broaden the eyes on inventing intellectual devices and equipment.

Coupling oxidation type semiconductors is a feasible strategy to improve the photocatalytic activity of reduction type g-C3N4 photocatalysts. In this work, Bi2O3 was used as an oxidation type semiconductor to construct direct Z-scheme Bi2O3/g-C3N4 photocatalysts by a one-step calcination method. The obtained Bi2O3/g-C3N4 composites exhibited excellent photocatalytic activity and stability toward methylene blue degradation under visible light irradiation. The composite with 1% weight content of Bi2O3 to g-C3N4 exhibited the highest photocatalytic activity with an apparent rate constant of 0.063 min−1, which was 3.0 and 3.7 times higher than that of pure Bi2O3 and g-C3N4, respectively. The enhanced photocatalytic activity of the Bi2O3/g-C3N4 composite was mainly attributed to the improved charge separation efficiency and stronger redox ability. This work gave a new insight in developing g-C3N4-based Z-scheme heterojunction photocatalysts with enhanced photocatalytic activity.

Metal/high-k dielectric core-shell nanocrystal (NC) memory capacitors were demonstrated by e-beam evaporation process. This kind of metal oxide semiconductor (MOS) memory shows good performance in charge storage, programming and erasing speeds. Compared to Co NC memory, Co/Al2O3 core-shell NC memory shows improved retention performance since the additional Al2O3 shell layer acts as a barrier, which prevent the leakage.

Metal/high-k dielectric core shell nanocrystal memory capacitor was demonstrated. This kind of MOS memory shows good performance in charge storage capacity, programming and erasing speed. By using a self-assembled Block Co-Polymer, Co/HfO2 core shell nanocrystals were well arrayed and showed uniform dot size and inter distance between dots. Compared with traditional metal nanocrystal fabrication process with E-Beam Evaporation followed by RTA (Rapid Thermal Annealing), core shell nanocrystal memory prepared by Block Co-Polymer produces a wide memory window of 8.4V at the ±12 V voltage sweep. Co/HfO2 core shell nanocrystals prepared by low-temperature Block Co-polymer process ensure high reliability of the devices.

Self-aligned TiSi2 coated Si nanocrystal nonvolatile memory is fabricated. This kind of MOSFET memory device is not only thermally stable, but also shows better performance in charge storage capacity, writing, erasing speed and retention characteristics. This indicates that CMOS compatible silicidation process to fabricate TiSi2 coated Si nanocrystal memory is promising in memory device applications.

NiSi2 nanocrystals were synthesized and used as the floating gate for nonvolatile memory application. Vapor-solid-solid mechanism was employed to grow the NiSi2 nanocrystals by introducing SiH4 onto the Ni catalysts-covered SiO2/Si substrate at 600°C. The average size and density of the NiSi2 nanocrystals are 7∼10nm and 3×1011 cm-2, respectively. Metal-oxide-semiconductor field-effect-transistor memory with NiSi2 nanocrystals was fabricated and characterized. Programming/erasing, retention and endurance measurements were carried out and good performances were demonstrated.

n-ZnO/i-CdZnO thin film was grown on p-type Si substrate by plasma-assisted molecular-beam epitaxy (MBE). Rectifying I-V curves show typical diode characteristics. Cyan electroluminescence emissions at around 473 nm were observed when the diodes were forward-biased at room temperature. The emission intensity increases with the increase of the injection current. Room temperature photoluminescence verifies the electroluminescence emissions come from CdZnO layer.

This work describes a novel nonvolatile memory device with self-aligned TiSi2/Si hetero-nanocrystal charge storage nodes. The TiSi2/Si hetero-nanocrystals can be readily fabricated using industrial standard self-aligned silicidation technique based on Si nanocrystals deposited on ultra-thin tunnel oxide with LPCVD. As compared with a Si nanocrystal memory device, a TiSi2/Si hetero-nanocrystal memory device exhibits faster programming and erasing, and longer retention time.

Co and Mn ions were implanted into n-type ZnO thin films with different electron carrier concentrations. X-ray diffraction measurements show that the ZnO:Co and ZnO:Mn thin films are of high crystallinity. From magnetization measurements, ferromagnetism was observed in both n-type ZnO:Co and n-type ZnO:Mn thin films with Curie temperatures well-above room temperature. Furthermore, the electron carrier concentration dependence of the saturated magnetization was measured in both types of thin films, and our results support an electron-mediated mechanism for ferromagnetism in ZnO:Co, as predicted by theory. However, our measurements seem to contradict theory for ZnO:Mn, which only predicts long-range ferromagnetism for p-type mediated material.

In this paper, we report a facile route, the tin vapor treatment method, to prepare tin oxide containing mesoporous silica composites (TOMS), which display room-temperature photoluminescence (RT-PL). Among them, TOMS-1 and TOMS-2 were synthesized from mesoporous silica SBA-15 and KIT-6, respectively. They are composed of amorphous SiO2 and tin oxide species and they display strong emission near ultraviolet (UV) when excited by UV light. By increasing the preparation temperature, their Sn content can be increased and subsequently their photoluminescence (PL) intensities can be greatly enhanced. Besides, their PL properties are revealed to be closely related to 2-fold-coordinated tin oxygen-deficient centers.

A solid-source GaP effusion cell was used to provide phosphorus dopants to achieve p-type ZnO with molecular-beam epitaxy (MBE). Room temperature (RT) Hall-effect measurements reveal that phosphorus-doped ZnO has a strong p-type conduction with a hole concentration of 6.5×1018 cm-3 and a hole mobility of 9.0 cm2/V s. X-ray diffraction measurements show a preferential growth orientation along <11-20> by θ-2θ scan and a tilt of ZnO (11-20) plane relative to the substrate surface by rocking curve and reciprocal space map. Photoluminescence (PL) spectra at 8.5 K show a dominant acceptor-bound exciton emission at 3.319 eV. The acceptor energy level of the phosphorus dopant is calculated to be 0.18 eV above the valence band from PL spectra, which is consistent with the temperature dependence of PL measurements.

Ga-doped n-type ZnO films were grown by molecular-beam epitaxy (MBE) on R-plane sapphire substrates. Material characterizations such as photoluminescence (PL), X-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS) and Hall measurements were carried out to characterize the optical, structural, and electrical properties of the film. Photoconductor devices for ultraviolet (UV) light detection were fabricated by depositing Al (250 nm)/Ti (20 nm) ohmic metal contacts. Linear characteristics were obtained from current-voltage (I-V) measurements that showed response to UV and visible illumination. Voltage dependent photocurrent (PC) spectra and responsivity spectrum were obtained to characterize the detection capability of the device in the UV region.

The transient process of the programming and erasing is very important for a nanocrystal-floating-gate flash memory. In this work, a computer simulation was carried out to investigate the charging, retention and erasing processes of our proposed Ge/Si hetero-nanocrystal floating gate flash memory. The transient gate current, the transient drain current and the average charge in one dot were simulated respectively. Evident hysteresis features can be observed in the transient processes in a voltage-sweeping measurement mode. While measuring the transient process in a constant voltage mode, the time decay of transient current and charge are weakened if Ge is used on the Si dot, indicating a longer retention time for Ge/Si-floating-gate flash memory.

The threshold voltage shift of a p-channel Ge/Si hetero-nanocrystal floating gate memory device was investigated both numerically and phenomenologically. The numerical investigations, by solving 2-D Poisson-Boltzmann equation, show that the presence of the Ge on Si dot tremendously prolongs the retention time, reflected by the time decay behavior of the threshold voltage shift. The increase of the thickness of either Si or Ge dot will reduce the threshold voltage shift. The shift strongly depends on the dot density. Nevertheless, only a weak relation between the threshold voltage shift and the tunneling oxide thickness was found. A circuit model was then introduced to interpret the behavior of threshold voltage shift, which agrees well with the results of the numerical method.

A simple approach has been developed for the synthesis of Au@CdS core-shell nanoparticles by a direct self-assembling process. Stable Au@CdS composite colloids were prepared by thiourea, as a double-functional reagent that acted as the linkage agent between Cd2+ ions and gold nanoparticles. The CdS-capped gold composite nanoparticles were successfully integrated into BaTiO3 films. A significant enhancement of third-order nonlinear optical susceptibility in the Au@CdS nanoparticles with core-shell structure is reported. To compare the effect of enhanced nonlinear response, single gold or CdS nanoparticles embedded in BaTiO3 films were also prepared.

Using lithography, and selective etching the Si1-xGex/Si multiple quantum well wires are fabricated. The characteristics of the selective chemical etching of Si1-xGex and Si are investigated, and high-performance etchants are developed. The etchant composed of HF:NH4F:H202:NH4OH is used for the etching of the epitaxial Si1-xGex films, the selectivity is better than 250 for Si0.76Ge0.24, and increases with the increase of the mole fraction x of Ge. Another etchant composed of NH4NO3:NH4OH is used for the etching of Si, the selectivity is higher than 1000 ( x ≥ 0.1 ). A preliminary photoluminescence (PL) result obtained from the Si0.76Ge0.24 multiple quantum well wires is presented. As the linewidth of the wires is reduced down to 50 nm, an intense complicated PL spectrum in the wavelength range of 500∼800 nm is observed at liquid nitrogen temperature. The origin of such spectrum is unclear.