Jyh-Ming Wu

The Preparation and High Photon-Sensing Properties of Fluorinated Tin Dioxide Nanowires

The photon-sensing abilities of SnO 2 nanowires have been investigated before and after surface fluorination by microwave plasma-enhanced chemical vapor deposition. The electrical conductance and photon-sensing abilities of SnO 2 nanowires were remarkably improved by an effective doping of fluorine into the surface of the nanowires. These results demonstrated that the fluorinated SnO 2 nanowires have potential applications as UV photodetectors with high photon-sensing properties.

Atomic Layer Deposition of Zinc Oxide on Multiwalled Carbon Nanotubes for UV Photodetector Applications

A novel process for the fabrication of ZnO-carbon nanotubes (CNT) nanocomposites with high uniformity by atomic layer deposition (ALD) of ZnO on multiwalled carbon nanotubes was reported, and their applications in UV photodetectors were investigated. Two types of photodetectors, p- and n-type, were developed by alternating the ALD reaction cycles. In addition, a schematic model was proposed to explain the p- to n-type conversion of the ZnO-CNTs, which accounts for the amount and surface coverage of ZnO on CNTs.

Enhancing the Photon-Sensing Properties of ZnO Nanowires by Atomic Layer Deposition of Platinum

Platinum nanoparticles were uniformily deposited on ZnO nanowires for photon-sensing applications. The morphology, size, and concentration of Pt particles on the ZnO nanowires can be controlled by varying the number of atomic layer deposition reaction cycles. The Pt-decorated ZnO nanowires exhibit much faster photon response and recovery speeds than the pristine ZnO nanowires. This provides an efficient route for strongly enhancing the photon-sensing properties of nanostructured metal oxides and fabricating photodetectors with fast response and recovery speeds.

Synthesizing and Comparing the Photocatalytic Activities of Single-Crystalline TiO2 Rutile Nanowires and Mesoporous Anatase Paste

Rutile TiO 2 nanowires and colloidal anatase paste (film-type) were synthesized on a silicon (Si) substrate by the thermal evaporation and sol-gel process, respectively. Field-emission scanning electron microscopy images showed nanowires with diameters of 60-90 nm and ∼ 3-4 μm in length. The morphology of the anatase paste was mesoporous, and the size of the nanoparticles was 20-40 nm in diameter. High-resolution transmission electron microscopy demonstrated that the rutile nanowires and anatase nanoparticles were single crystalline. Comparison of their photocatalytic properties revealed that the rutile nanowires had high specific surface area, were well-crystallized, and possessed photocatalytic activities as high as those of the mesoporous anatase paste.

Preparation of Pt / SnO2 Core–Shell Nanowires with Enhanced Ethanol Gas- and Photon-Sensing Properties

Pt/SnO 2 core-shell nanowires were prepared by a process that involves thermal evaporation of SnO 2 nanowires and subsequent atomic layer deposition of Pt, and their gas- and photon-sensing properties were investigated systematically. Transmission electron microscopy analysis showed that the Pt shell with a thickness of 8.8 nm is composed of numerous Pt nanoparticles with average diameters of ∼5.3 nm. The Pt/SnO 2 core-shell nanowires with high electrical conductance exhibit remarkably enhanced ethanol gas- and photon-sensing properties due to the surface functionalization resulting from the effective Pt catalyst and the formation of hetero-nanostructures fabricated by the SnO 2 core and Pt shell.

Characterization and Cathodoluminescence of Beak-Like SnO2 Nanorods

Single crystalline tetragonal rutile SnO2 nanorods with curved beak-like tips of various lengths were synthesized using Au as a catalyst by thermal evaporation with different precursor flow rates. The cathodoluminescence (CL) spectrum shows that the long beak-like SnO2 nanorods exhibit stronger orange emission at 600 nm, while the short beak-like SnO2 nanorods exhibit stronger blue emission at 480 nm. The morphology and optical properties can be modified by altering the oxygen content.

Selected-Area Growth of SnO2 Nanowires on TiO2 Layer through Reduction of Hydrogen Gas

SnO2 nanowires were grown on a TiO2/ATO (antimony doped tin dioxide) glass substrate by thermal evaporation at ~750 °C without any source material (tin oxide powder or metal tin). A SnO2 layer was melted and evaporated from ATO glass substrate. Hydrogen served as a reductant, causing vapor species of SnO and O2 to be formed from the SnO2 layer. The patterned TiO2 layer provided sites with a high surface energy such that the selected-area growth of SnO2 nanowires was achieved. A growth model, based on a vapor–liquid–solid mechanism, for interpreting the growth of the nanowires in our work is proposed. Field emission scanning electron microscopy (FESEM), high-resolution transmission emission microscopy (HRTEM), and cathodoluminescence (CL) were used to characterize the nanowires.