[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above.

Metal oxide gas sensors: Sensitivity and influencing factors

Transparent conductors as solar energy materials: A panoramic review

Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion Besides, doping is also an effective method to decrease particle size and improve gas sensing properties Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given

/pdf/metal-oxide-nanostructures-and-their-gas-sensing-properties-5exdmrct20.pdf

Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

Aligned Single‐Crystalline Si Nanowire Arrays for Photovoltaic Applications

Factors Affecting the Performance of HJT Silicon Solar Cells in the Intrinsic and Emitter Layers: A Review

Silver (Ag) nanoparticles were formed on fluorine-doped tin oxide (FTO) coated glass substrate, and then hydrogenated amorphous silicon (a-Si:H) thin-film solar cells were sequentially fabricated. Ag nanoparticles located in the interface between the FTO and the p-layer leads to a light-trapping effect because of the strong light-material interaction in Ag nanoparticles and enhancement of the optical path length. A higher haze ratio appeared for Ag nanoparticles with larger diameters and heights, compared with the conventional type. The device with the Ag nanoparticles showed a short-circuit current density of 12.66 mA cm−2, which was 2.2 mA cm−2 higher than the device without Ag nanoparticles. Conversion efficiency increased from 4.9 % to 5.9 % by employing Ag nanoparticles with a roughness of 71 nm. The simple process makes our design useful for low-cost, high conversion efficiency thin-film solar cells.

Improvement of a‐Si:H Thin‐film Solar Cells by Employing Large Ag Nanoparticles

Layer transfer process has emerged as a promising tool in the field of thin silicon solar cell technology. This process can use mono-crystalline silicon as a surface for the epitaxial growth of a thin layer of silicon. It requires some sort of surface conditioning of the substrate due to which the surface become suitable for homo-epitaxy and lift off after solar cell fabrication. The successful reuse of substrate has been reported. The use of the conditioned surface without any kind of epitaxial layer growth is also the issue to be addressed. This review paper basically describes the five most cost effective methods on which works are in progress. Several types of possible problems envisaged by different research groups are also incorporated here with necessary discussion. Work in Korea has already started in this area in collaboration IC Design and Fabrication Centre, Jadavpur University, India and that also has been mentioned.

Current Status of Layer Transfer Process in Thin Silicon Solar Cell : a review

Photovoltaic-electrolysis water splitting (PV-EWS) is the most promising approach for high solar-to-hydrogen (STH) efficiency. The present PV-EWS systems achieve the highest STH performance by using a III-V triple-junction configuration, which, however, involves a complex and expensive manufacture process. Therefore, in this work, we demonstrate a III–V double junction device that can be used as an alternative to the III–V triple-junction device for high STH conversion efficiency of the PV-EWS systems. We estimate the STH performance via coupling world-recorded multi-junction photovoltaic (PV) and our experimented cell configurations with an EWS system. The results show that the III–V double junction, owing to the good trade-off between the efficiency loss and compensation, exhibits a higher STH efficiency than the III–V triple-junction. Furthermore, strategies for improving the efficiency of the III–V double junction device for low-cost PV-EWS system are discussed.

/pdf/photovoltaic-partner-selection-for-high-efficiency-2312czmxxm.pdf

Photovoltaic Partner Selection for High-Efficiency Photovoltaic-Electrolytic Water Splitting Systems: Brief Review and Perspective

The lower mobility for p-type Ge based is always an issue due to slow traps generation at the interface of the metal oxide semiconductor (MOS) device which designates the defects in films generated during the deposition process. One of the effective ways to reduce this slow traps generation is to perform post deposition annealing (PDA) at a certain temperature. However, the selection of proper annealing temperature is the key to reduce defects without damaging the film quality. The effect of different PDA temperatures on the slow traps generation mechanism in the GeON passivated Ge MOS device was examined in this work. The XPS spectra show the stable formation of GeON over Ge, while HRTEM does not show any effect of PDA at the interface of GeON/Ge. The slow trap density (ΔNst) in HfO2/GeON/Ge interface annealed at different temperatures was evaluated from the hysteresis curve of C-V sweep as the function of the effective oxide field. The lowest ΔNst (4.01 × 1012 cm−2) was observed for the PDA temperature for 400 ℃. While, ΔNst increased slightly after PDA at 450 ℃. The work suggests that PDA at lower temperatures is essential to realize the high quality interface with lower interface trap density, enhanced mobility and lower CET in Ge based MOS devices. Further, it also helps to reduce the slow traps generations at the interface.

Junsin Yi

Papers

Factors Affecting the Performance of HJT Silicon Solar Cells in the Intrinsic and Emitter Layers: A Review

Improvement of a‐Si:H Thin‐film Solar Cells by Employing Large Ag Nanoparticles

Current Status of Layer Transfer Process in Thin Silicon Solar Cell : a review

Photovoltaic Partner Selection for High-Efficiency Photovoltaic-Electrolytic Water Splitting Systems: Brief Review and Perspective

Temperature-dependent study of slow traps generation mechanism in HfO2/GeON/Ge(1 1 0) metal oxide semiconductor devices