Narrow Results

We describe the fabrication of the CAVET (Current Aperture Vertical Electron Transistor) by Photoelectrochemical (PEC) formation of a current aperture. Etch process is quite naturally critical to the achievement of the etched aperture in CAVET. We provide some background on that etch process, and the subsequent modification and optimization of the process for CAVET fabrication.

Carbon nanotips were grown on a silicon substrate by negative bias-enhanced hot filament chemical vapor deposition without catalyst, using a mixture of methane, ammonia and hydrogen as the reaction gases. It was evidenced that the plasma caused by the bias played a key role in the formation of the carbon nanotips. Due to occurrence of plasma during growing carbon nanotips, the gases were ionized into various ions. Based on different effects of the ions, a growth mechanism of the carbon nanotips was put forward.

Surfaces of polycrystalline Al samples were treated by using electropolishing, etching or mechanical polishing methods. Surface morphologies, laser-induced damage thresholds (LIDTs) and ejected particle numbers of different samples were analyzed and compared. Results showed that several different surface morphologies of Al were prepared. A new surface electropolishing technique was developed and an improvement of 95% of LIDT of Al was obtained by using this method. Ejected particle numbers of different samples were monitored and compared to investigate their damage-resistant properties. The particle numbers ejected from the electropolished sample are much smaller than those of etched or mechanically polished samples under Q-switched 355-nm Nd:YAG laser irradiation at 6.8 ns pulses.

Plasma etching technology is an indispensable processing method in the manufacturing process of semiconductor devices. Because of the high fluorine/carbon ratio of CF₄, the CF₄ gas is often used for etching SiO₂. A commercial software ESI-CFD is used to simulate the process of plasma etching with an inductively coupled plasma model. For the simulation part, CFD-ACE is used to simulate the chamber, and CFD-TOPO is used to simulate the surface of the sample. The effects of chamber pressure, bias voltage and ICP power on the reactant particles were investigated, and the etching profiles of SiO₂ were obtained. Simulation can be used to predict the effects of reaction conditions on the density, energy and angular distributions of reactant particles, which can play a good role in guiding the etching process.

Research on the improvement of the photoelectric conversion efficiency of solar cells is always the focus. In this paper, an efficient anti-reflection micro/nanostructure is proposed to improve the conversion efficiency of the solar cell. Graded effective refractive index theory is used to achieve the anti-reflection effect while the simulation model is established by FDTD. A specific periodic nanostructure is obtained, which can achieve a good anti-reflection effect. According to the simulation model, the reflectivity of the solar cell is reduced by 0.85% and the transmittance is increased by 0.85% in the band range of 200 nm to 1000 nm. Specifically, high anti-reflection phenomena are obtained in the band range of ultraviolet and blue light, in which the reflectivity is reduced by 1.56% and the transmittance is increased by 1.55%. Based on the simulation results, the array nanostructure is produced by etching the self-assembled polystyrene (PS) microspheres. Finally, the required structure is formed on the silicon wafer by nanoimprinting and etching technology. The reflectivity of 2.8% is obtained on silicon, which can potentially increase the opto-electrical performance of the solar cell.

Wool fiber is commonly used in textile industry, however, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling, and dyeability. These problems may be attributed mainly in the presence of wool scales on the fiber surface. Recently, chemical treatments such as oxidation and reduction are the commonly used descaling methods in the industry. However, as a result of the pollution caused by various chemical treatments, physical treatment such as low temperature plasma (LTP) treatment has been introduced recently because it is similarly capable of achieving a comparable descaling effect. Most of the discussions on the applications of LTP treatment on wool fiber were focused on applying this technique for improving the surface wettability and shrink resistance. Meanwhile, little discussion has been made on the mechanical properties, thermal properties, and the air permeability. In this paper, wool fabric was treated with LTP treatment with the use of a non-polymerizing gas, namely oxygen. After the LTP treatment, the fabrics low-stress mechanical properties, air permeability, and thermal properties were evaluated and discussed.

Metal-doped ZnO films with various metal contents (Al, Ag and Li of 0–10 wt.%) were prepared by RF magnetron sputtering system with specially designed ZnO targets. The structural, optical and electrical properties of MZO films depended on the type and content of doping in target. Electrical resistivity of LZO thin films increased with increasing Li doping amounts between 0 and 4 wt.%, suggesting that an epitaxial LZO film has high resistivity. We observed morphology in pure ZnO films by using different etchant. In addition, etching rate were contrasted with the etchant concentration and pH. The etching rate is proportional exponentially to pH value. These data will be the technical basis for TCO application. Also, the dry etching rate decreased with increasing the Cl₂ concentration in CH₄/H₂/Ar + additive Cl₂ gas mixture but metal dopants were etched effectively.

ZnO:Al (AZO) transparent conductive films used for solar cells were prepared by DC magnetron sputtering technology. The influence of substrate temperature on the electrical and optical properties of the films was studied. Further, the AZO films prepared were etched in diluted hydrochloric acid. The film surface morphology after etching for different time was researched.

Sulphur hexafluoride (SF₆) is used as an insulator in high-voltage systems. An electrical breakdown dissociates (SF₆). Therefore, the insulating efficiency is degraded. If the (SF₆) is not renewed, failure of the system can occur. A monitoring device for (SF₆) loss is required, and an optical fiber sensor for continuous monitoring of (SF₆) degradation in high-voltage switchgear has been developed. Dissociation products of the (SF₆) discharge include HF and atomic F, both of which react readily with silica. This reactivity is utilized in our sensor, where etching of a glass fiber surface modifies the transmission characteristics of the fiber.

In the this study, we focus on the growth of a metal-organic creatininium borate (CRB) single crystal for third-order nonlinear optical (NLO) applications. Optically transparent & wide optical band gap single crystals of CRB were successfully harvested by adopting a slow evaporation solution technique (SEST) at a constant 40${}^{\circ }$C temperature. The structural identification and lattice parameters of the grown sample were determined by powder X-ray diffraction (PXRD) using Rietveld analysis by FullProf Suite software. The occurrence of vacancy/interstitial defects produced during growth was investigated by high-resolution X-ray diffraction (HRXRD) using omega scan arrangement. A single peak with lower full width half maxima (56.4 arc s) was obtained from the scan which suggests that there were no grain boundaries for the grown crystal. Surface morphology and its features such as concentration of dislocations and defect sites on the as-grown sample were scrutinized using the etching technique. The optical band gap and UV–vis cut-off were examined and found to be 5.39 eV and 230 nm, respectively. Photoluminescence characteristics of the crystal show an emission at 377 nm upon excitation with a wavelength of 336 nm. The presence of radiative and non-radiative transitions inside the crystal due to excitation upon 266 nm laser was identified using time-resolved photoluminescence. Thermal stability and decomposition temperature of the compound were obtained by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The third-order nonlinearity of the crystal was determined by Z-scan measurement technique with a femtosecond Ti-sapphire laser.

Diamond whiskers were formed by etching diamond thin films using metal clusters as a shadow mask, which were deposited on the diamond film before or during etching. The whiskers were as thin as 100 nm and the density was as high as 10¹⁰/cm². The secondary electron emission yield of the diamond whiskers was significantly reduced as compared to the initial diamond film. The decrease in the yield was more significant if the primary electrons were impinged in parallel direction with the whiskers. We suggest that absorption of the secondary electrons in the narrow gap between the whiskers was the reason for the decreased yield.

It is experimentally shown that, unlike evaporation drying, supercritical CO₂ drying makes it possible to obtain free-standing single-coil InGaAs/GaAs nanotubes and other nanoshells with wall thicknesses down to 1 nm without their deformation by capillary forces. The performed process optimization has allowed us to reduce tenfold the duration of the process for long nanotubes. For the first time, etching of sacrificial AlAs layers in supercritical media was performed.

A new colorimetric method for the detection of chemotherapeutic drug 6-mercaptopurine (6-MP) is developed based on controlling localized surface plasmon resonance (LSPR) of triangular silver nanoplates (AgNPs). The triangular AgNPs can be etched by trace amount of Cl⁻ and transformed to a disc-like shape, accompanied by a blueshift of the corresponding LSPR absorption band. With the protective effect of 6-MP, the AgNPs are hardly or partly to be etched by Cl⁻, resulting in a reversed shift of LSPR. Based on a linear relationship between LSPR wavelength change and the concentration of 6-MP, a fast, visual and selective method for 6-MP assay is established. This method has been successfully applied to the detection of 6-MP in tablets.

BiOBr-based photocatalysts have received extensive interest for photocatalytic nitrogen fixation due to their layered structure recently. In this study, BiOBr with enhanced photocatalytic nitrogen fixation performance was synthesized via a facile ozone modification method. Characterization results demonstrated that the ozone treated BiOBr photocatalysts have identical crystal structures, morphologies, and enhanced photocatalytic nitrogen fixation performance. In addition, due to the strong oxidation of ozone, more oxygen vacancies and active sites form on the BiOBr surface, which could improve the nitrogen fixation efficiency. Furthermore, a supposed photocatalytic nitrogen fixation mechanism of the ozone treated BiOBr is proposed.

We describe the fabrication of the CAVET (Current Aperture Vertical Electron Transistor) by Photoelectrochemical (PEC) formation of a current aperture. Etch process is quite naturally critical to the achievement of the etched aperture in CAVET. We provide some background on that etch process, and the subsequent modification and optimization of the process for CAVET fabrication.

The following sections are included:

• Introduction

• Etching and CVD Experiments
  • Experimental Systems
    • Beamline and Multilayered Mirror Monochromator
    • Reaction Chamber
  • Etching and Unique Material-Selectivity
  • CVD and Unique Material-Selectivity
  • SR Assisted Epitaxial Growth
  • SR Irradiation Effects on the Low Temperature Condensed Layer of Dimethyl Aluminum Hydride (DMAH)

• In Situ Monitoring Techniques and Reaction Mechanism Study
  • BML-IRAS
    • Principle of BML-IRAS
    • Application of BML-IRAS to Reaction Mechanism Study of SR Assisted GS-MBE
    • IRAS with SR Irradiation Effects on Chemisorbed Hydrogen/Si(100)
  • Scanning Tunnelling Microscopy (STM)

• Core Electron Excitation in SR Process

• Future Prospects: Nanostructure Fabrication by SR Processes

• Acknowledgment

• References

Atomic force microscopy (AFM) was originally developed for atomic resolution surface topography observations. Nowadays, it is also widely used for nanolithography. AFM-based lithography is an effective method compared to conventional photolithographic processes due to its simplicity, high resolution, and low cost. It can provide nanoscale stage control and the probing tip can be used as a lithographic tool. Therefore, various AFM-based nanoscale fabrication methods have been proposed using electrochemical oxidation, material transfer, mechanical lithography, and thermally induced modifications. This chapter will introduce the detailed processes and applications of AFM-based lithographic techniques.

Diamond whiskers were formed by etching diamond thin films using metal clusters as a shadow mask, which were deposited on the diamond film before or during etching. The whiskers were as thin as 100 nm and the density was as high as 10¹⁰/cm². The secondary electron emission yield of the diamond whiskers was significantly reduced as compared to the initial diamond film. The decrease in the yield was more significant if the primary electrons were impinged in parallel direction with the whiskers. We suggest that absorption of the secondary electrons in the narrow gap between the whiskers was the reason for the decreased yield.

This study addresses unreported features for Cu DC-magnetron sputtering on cotton mediating inactivation of Escherichia coli K12 (from now on E. coli). The E. coli inactivation for cotton-Cu samples sputtered for 40 s was attained within 30 min under visible light (1.2 mW/cm²) and within 120 min in the dark. For a longer sputtering time of 180s, the bacterial inactivation kinetics under light was observed within 30 min, as was the case for the 40 s sputtered sample. This suggests that Cu-ionic species play a key role E. coli inactivation. The 40 s sputtered samples present the highest amount of Cu-sites held in exposed positions interacting on the cotton surface (or inside the cotton) with E. coli. Sputtering for 40 s deposited 4.10¹⁶ atoms Cu/cm² (taking ~10¹⁵ atoms/cm Cu per atomic layer) and this was the threshold amount of Cu necessary for complete E. coli inactivation. Cu DC-magnetron sputtering lead to thin metallic semi-transparent grey-brown Cu-coating presenting hydrophobic behavior as determined by contact angle measurements.