There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

One-dimensional (1D) ZnO nanostructures have been studied intensively and extensively over the last decade not only for their remarkable chemical and physical properties, but also for their current and future diverse technological applications. This article gives a comprehensive overview of the progress that has been made within the context of 1D ZnO nanostructures synthesized via wet chemical methods. We will cover the synthetic methodologies and corresponding growth mechanisms, different structures, doping and alloying, position-controlled growth on substrates, and finally, their functional properties as catalysts, hydrophobic surfaces, sensors, and in nanoelectronic, optical, optoelectronic, and energy harvesting devices.

/pdf/one-dimensional-zno-nanostructures-solution-growth-and-30xs4d6be7.pdf

One-dimensional ZnO nanostructures: Solution growth and functional properties

ZnS nanostructures: From synthesis to applications

CuO nanostructures: Synthesis, characterization, growth mechanisms, fundamental properties, and applications

Scientists describe a size-selective quantum dot patterning technique that involves kinetically controlling the nanotransfer process without a solvent. The resulting printed quantum dot films exhibit excellent morphology and a well-ordered quantum dot structure. This technique allows fabrication of a 4-inch (or larger) thin-film transistor display with high colour purity and extremely high resolution.

Full-colour quantum dot displays fabricated by transfer printing

A ZnO nanowire-based humidity sensor

In this letter, we report the fabrication of an amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor with a high-k dielectric layer on a glass substrate. The room-temperature-deposited a-IGZO channel with Ta2O5 exhibits the following operating characteristics: a threshold voltage of 0.25 V, a drain-source current on/off ratio of 105, a subthreshold gate voltage swing of 0.61 V/decade, and a high field-effect mobility of 61.5 cm2/V·s; these characteristics make it suitable for use as a switching transistor and in low-power applications.

High-Performance a-IGZO Thin-Film Transistor Using $ \hbox{Ta}_{2}\hbox{O}_{5}$ Gate Dielectric

Vertically well-aligned ZnO nanowire ultraviolet (UV) photodetectors were fabricated by spin-on-glass technology on ZnO:Ga/glass templates. With 2V applied bias, it was found that dark current density of the fabricated device was only 2.0×10−7A∕cm2. It was also found that UV-to-visible rejection ratio and quantum efficiency of the fabricated ZnO nanowire photodetectors were more than 1000 and 12.6%, respectively.

/pdf/ultraviolet-photodetectors-with-zno-nanowires-prepared-on-3spqcs3lyq.pdf

Ultraviolet photodetectors with ZnO nanowires prepared on ZnO:Ga/glass templates

The investigation explores the fabrication and characteristics of ZnO nanowire (NW)/p-GaN/ZnO NW heterojunction light-emitting diodes (LEDs). Vertically aligned ZnO NWs arrays were grown on the p-GaN substrate. The n-p-n heterojunction LED was fabricated by combining indium tin oxide/glass substrate with the prepared ZnO NWs/p-GaN substrate. The symmetrical rectifying behavior demonstrates that the heterostructure herein was formed with two p-n junction diodes and connected back to back. The room-temperature electroluminescent emission peak at 415 nm was attributed to the band offset at the interface between n-ZnO and p-GaN and defect-related emission from ZnO and GaN. Finally, the photograph indicated the LED clearly emitted blue light.

Electroluminescence from n-ZnO nanowires/p-GaN heterostructure light-emitting diodes

In this study, the growth of high-density single-crystalline ZnO nanowires on patterned ZnO:Ga/ SiO2/Si templates was reported. We also adsorbed Au onto nanowire surfaces and fabricated ZnO nanowire acetone vapor sensors. With 200-ppm acetone vapor concentration, it was found that we could enhance the device sensitivities at 300deg C from 18.5% to 82.5% by Au adsorption. It was also found that measured responses at 300degC were around 52%, 61%, 71%, 77%, and 82% when the accumulative acetone vapor concentration reached 5, 10, 50, 100, and 200 ppm, respectively, for the ZnO nanowire sensor with Au adsorption.

Sheng Po Chang

Papers

A ZnO nanowire-based humidity sensor

High-Performance a-IGZO Thin-Film Transistor Using $ \hbox{Ta}_{2}\hbox{O}_{5}$ Gate Dielectric

Ultraviolet photodetectors with ZnO nanowires prepared on ZnO:Ga/glass templates

Electroluminescence from n-ZnO nanowires/p-GaN heterostructure light-emitting diodes

Highly Sensitive ZnO Nanowire Acetone Vapor Sensor With Au Adsorption