[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

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Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

Aligned Single‐Crystalline Si Nanowire Arrays for Photovoltaic Applications

Current Status of High-efficiency a-Si/c-Si Heterojunction Solar Cells: A Review

Integration of Subcells in III-V//Si Tandem Solar Cells

The effect of hydrogen capping of SiN(Si-rich)/SiN(N-rich) stacks for n-type 	c-Si solar cells was investigated. Use of a passivation layer consisting of Si-rich SiN with a refractive index (n) of 2.7 and N-rich SiN with a refractive index of 2.1 improved the thermal stability. A single SiN passivation layer with a refractive index of 2.05 resulted in an initial lifetime of 200 μs whereas the layer with a refractive index of 2.7 resulted in a high initial lifetime of 2 ms, but the layer degraded rapidly after firing. A stacked passivation layer with refractive indices of 2.1 and 2.7 had a stable lifetime of 1.5 ms with an implied open-circuit voltage (iV
 oc) of 720 mV after firing. The thermally stable passivation mechanism with changing amounts of Si–N and Si–H bonding was analyzed by Fourier-transform infrared (FTIR) spectroscopy. Incorporation of the SiN
 x
 stack layer (2.7 + 2.1) into the passivated rear of n-type Cz silicon screen-printed solar cells resulted in energy conversion efficiency of 19.69%. Improved internal quantum efficiency in the long-wavelength range above 900 nm, with V
 oc of 630 mV, is mainly because of superior passivation of the rear surface compared with conventional solar cells.

Improved Hydrogen Capping Effect in n -Type Crystalline Silicon Solar Cells by SiN(Si-Rich)/SiN(N-Rich) Stacked Passivation

Failures of porcelain insulators due to ice formation, corrosive pollutant deposition, and cracks result in significant power losses in the power transmission system. Using a simple three-step sprayable coating technique, we propose a novel superhydrophobic material for high-voltage insulator surface protection with water absorption resistance, self-cleaning, ice-phobic, and crack healing capabilities. An adhesive polydopamine layer sprayed on an insulator surface to predevelop a macro–nano hierarchical surface based on an oleic acid/nano-SiO2 composite with an oleic acid infusion arrangement is a crucial endurance technique. The technique shows less than 3% water absorbance, more than 150° contact angle, less than 2° contact angle hysteresis, self-cleaning ability, ice-phobic with a minimum ice adhesion strength of 15.5 ± 9.9 kPa, and crack-healing characteristics after corrosive, thermal, and mechanical aging. Such sustainable, long-lasting, and facile techniques would find widespread applications in the power, civil, marine, and aviation industries. 

Sprayable Superhydrophobic Polydopamine-Modified Oleic Acid/Nanoscale SiO2 Composites for Insulator Protective Coatings

In addition to the different technologies of silicon solar cells in crystalline form, TOPCon solar cells have an exceptionally great efficiency of 26%, accomplished by the manufacturing scale technique for industrialization, and have inordinate cell values of 732.3 mV open-circuit voltage (Voc) and a fill factor (FF) of 84.3%. The thickness of tunnel oxide, which is less than 2 nm in the TOPCon cell, primarily affects the electrical properties and efficiency of the cell. In this review, various techniques of deposition were utilized for the layer of SiOx tunnel oxide, such as thermal oxidation, ozone oxidation, chemical oxidation, and plasma-enhanced chemical vapor deposition (PECVD). To monitor the morphology of the surface, configuration of annealing, and rate of acceleration, a tunnel junction structure of oxide through a passivation quality of better Voc on a wafer of n-type cell might be accomplished. The passivation condition of experiments exposed to rapid thermal processing (RTP) annealing at temperatures more than 900 °C dropped precipitously. A silicon solar cell with TOPCon technology has a front emitter with boron diffusion, a tunnel-SiOx/n+-poly-Si/ SiNx:H configuration on the back surface, and electrodes on both sides with screen printing technology. The saturation current density (J0) for such a configuration on a refined face remains at 1.4 fA/cm2 and is 3.8 fA/cm2 when textured surfaces of the cell are considered, instead of printing with silver contacts. Following the printing of contacts with Ag, the J0 of the current configuration improves to 50.8 fA/cm2 on textured surface of silicon, which is moderately lesser for the metal contact. Tunnel oxide layers were deposited using many methods such as chemical, ozone, thermal, and PECVD oxidation are often utilized to deposit the thin SiOx layer in TOPCon solar cells. The benefits and downsides of each approach for developing a SiOx thin layer depend on the experiment. Thin SiOx layers may be produced using HNO3:H2SO4 at 60 °C. Environmentally safe ozone oxidation may create thermally stable SiOx layers. Thermal oxidation may build a tunnel oxide layer with low surface recombination velocity (10 cm/s). PECVD oxidation can develop SiOx on several substrates at once, making it cost-effective.

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Junsin Yi

Papers

Current Status of High-efficiency a-Si/c-Si Heterojunction Solar Cells: A Review

Integration of Subcells in III-V//Si Tandem Solar Cells

Improved Hydrogen Capping Effect in n -Type Crystalline Silicon Solar Cells by SiN(Si-Rich)/SiN(N-Rich) Stacked Passivation

Sprayable Superhydrophobic Polydopamine-Modified Oleic Acid/Nanoscale SiO2 Composites for Insulator Protective Coatings

Tunnel Oxide Deposition Techniques and Their Parametric Influence on Nano-Scaled SiOx Layer of TOPCon Solar Cell: A Review