Tetrapod-like zinc oxide (ZnO) nanostructures can be synthesized by rapid heating metal zinc pellet at 900 °C under air ambient. Catalyst, vacuum, and carrying gas are not necessary, and more importantly, it is a volcanic process for rapid and mass production. The turn-on field of the synthesized tetrapod-like ZnO nanostructures is found to be as low as 1.6 V/μm at the current density of 1 μA/cm2. These ZnO nanostructures are technologically useful for vacuum electron devices because they can be easily and economically synthesized and deposited on large substrates.

Rutile ͑110͒ tin dioxide nanowires synthesized by thermal oxidation of tin powders and having a band gap of 4.2 eV were annealed in vacuum and O 2 at 600°C for 1 h. The photoluminescence ͑PL͒ properties of the as-grown and annealed samples were measured from 10 to 300 K. The nanowires annealed in O 2 showed weak luminescence at 393 nm at temperatures below 100 K, and no luminescence could be detected at temperatures higher than 100 K. In contrast, the nanowires annealed in vacuum exhibited strong luminescence at 480 nm at temperatures lower than 100 K and at 600 nm when the temperature was higher than 100 K. Our PL results show that the emissions originate from the defect electronic states in the band gap formed by surface oxygen vacancies and solve the long-time controversy over the origin of the luminescence.

A low-temperature silicon direct-bonding technique has been researched using variant plasma ͑N 2 , O 2 , Ar, and H / He͒ pretreatment prior to bonding for surface activation. In plasma bonding, after annealing at 300°C for an hour the authors get a bonding energy of about 2 -2.5 J / m 2 , which is near the fracture strength of bulk silicon. In Si-Si wafer bonding, our experiments demonstrate that the origin of voids appearing in low-temperature annealing is related to the plasma variety and activation conditions. The authors believe that the annealing voids and bubbles, which appear and accumulate at the microdefects, are caused by plasma activation. They used an optimized O 2 and H / He plasma-activation process for wafer direct bonding and obtained a high surface energy, void-free hydrophilic Si-Si wafer bonding. The wafers' root-mean-square surface roughness after plasma activation was measured by an atomic force microscope. The cross-sectional image of the bonding interface was observed by a scanning electron microscope. Compared with the standard wet-chemical surface treatment that requires high-temperature annealing ͑Ͼ1000°C͒, both the low-temperature and shorter time annealing using plasma pretreatment are suitable for the microelectromechanical systems manufacture process and wafer-scale packaging.

Metal–insulator–semiconductor (MIS) structures containing Ge nanocrystals embedded in high permittivity dielectrics (ZrO2/Al2O3) are fabricated by electron-beam evaporation method. Capacitance–voltage (C–V) and I–V characteristics of the fabricated MIS structures are investigated in the dark and under illumination. Charge storing and negative photoconductivity effects of the Ge nanocrystals are experimentally demonstrated by the hysteresis in the C–V curves and the decrease of the current under illumination at a given voltage, respectively.

Rod-shaped and wire-shaped SnO2 nanowhiskers were synthesized by thermal evaporating of tin powders at 900 °C. Three Raman peaks (474, 632, 774 cm−1) showed the typical feature of the rutile phase of as-synthesized SnO2 nanowhiskers, which was consistent with the result of x-ray diffraction. A relatively low turn-on field of 1.37 V µm−1 at a current density of 0.1 µA cm−2 was obtained. The dependence of emission current density on the electric field followed a Fowler–Nordheim relationship. Our results indicated that SnO2 nanowhiskers had an interesting FE property as a wide band gap semiconductor.