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Two-dimensional transition metal dichalcogenides (TMDCs) have emerged as promising materials for next-generation electronics due to their excellent semiconducting properties. However, high contact ...

With the development of the Internet of Things (IoT), indoor photovoltaics are attracting considerable interest owing to their potential to benefit various IoT-related fields. Therefore, this study investigates the use of transparent hydrogenated amorphous silicon (a-Si:H) solar cells for a broad range of applications, including indoor light harvesting. High-gap triple layers were employed in the a-Si:H solar cells to obtain a high shunt resistance and high short-circuit current

This study explores the relationship between energy, the environment, and society in early modern Korea, after its initial contact with electricity and fossil fuels. After reviewing the literature and original sources, the study reached four findings. First, the introduction of electricity and new energy sources was intensely pursued under the belief that civilization and enlightenment based on electricity, fossil fuels, and their relevant Western technologies could help Korea retain its national sovereignty and compete with imperial powers during the gaehwa period. Second, the traditional Korean worldview regarding the interrelationship between humans and nature was partially changed by the introduction of electricity and new energy sources. Third, using electricity and new energy sources changed the way traditional social relations were experienced in Korea, as well as conventional notions of time and space. Lastly, Seoulites in early modern Korea were psychologically prepared to accept and become familiar with electricity and new energy sources, which eventually became the foundation for mentally reorienting Korea toward future industrialization.

Two-dimensional (2D) material-based heterostructures provide a unique platform where interactions between stacked 2D layers can enhance the electrical and opto-electrical properties as well as give rise to interesting new phenomena. Here, the operation of a van der Waals heterostructure device comprising of vertically stacked bilayer MoS2 and few layered WSe2 has been demonstrated in which an atomically thin MoS2 layer has been employed as a tunneling layer to the underlying WSe2 layer. In this way, simultaneous contacts to both MoS2 and WSe2 2D layers have been established by forming a direct metal–semiconductor to MoS2 and a tunneling-based metal–insulator–semiconductor contacts to WSe2, respectively. The use of MoS2 as a dielectric tunneling layer results in an improved contact resistance (80 kΩ μm) for WSe2 contact, which is attributed to reduction in the effective Schottky barrier height and is also confirmed from the temperature-dependent measurement. Furthermore, this unique contact engineering and...

We demonstrate a high-performance photodetector with multilayer tin diselenide (SnSe2) exfoliated from a high-quality crystal which was synthesized by the temperature gradient growth method. This SnSe2 photodetector exhibits high photoresponsivity of 5.11 × 105 A W-1 and high specific detectivity of 2.79 × 1013 Jones under laser irradiation (λ = 450 nm). We also observed a reproducible and stable time-resolved photoresponse to the incident laser beam from this SnSe2 photodetector, which can be used as a promising material for future optoelectronic applications.

Transparent hydrogenated amorphous silicon (a-Si:H) thin-film solar cells, in which the colors of the front and rear faces can be adjusted individually, were developed for implementation in building-integrated photovoltaic (BIPV) windows. The proposed ultrathin transparent multilayered electrodes (TMEs) are highly conductive and transparent, consisting of a bottom layer of gallium-doped zinc oxide (GZO), a thin metal layer of Ag, and an optoelectronic controlling layer (OCL) of GZO. They can be used for both the front and rear electrodes of transparent a-Si:H solar cells, and the resulting solar cells show a 5.0% average power conversion efficiency and 18.3% average transmittance. The various dual colors on the front and rear of the cell can be individually adjusted by changing the thickness of the OCL on each face of the TME, without significantly changing the efficiency. The cell colors were quantitatively investigated using the color coordinates in a chromaticity diagram based on the International Commission on Illumination (CIE; 1931) standard to show that the simulated and observed colors match well under both LED and fluorescent light sources. We also show that the observable color of the BIPV windows is determined by indoor and outdoor light sources, and dynamically varies as a function of illuminance of the light source as the day gradually progresses into night. This study helps to elucidate the color behavior of the BIPV windows and to develop a-Si:H BIPV windows that show various colors with stable electrical power generation.

We investigate the multiscale roles of renewable energy cooperatives (RE co-ops) in South Korea. This paper focuses on citizen participatory RE co-ops as a niche that plays a vital role in the community-led energy pathway. This paper conducted a narrative analysis based on data about RE co-ops' current status and in-depth interviews. We analyzed core changes and inertia in the conventional energy system at the national, regional, and local scales by comparing within and between scales. Each scale consisted of a patchwork of distinguishable subregimes, i.e., market, policy, and culture. We argue that a niche plays the creative role of adjusting the subregimes at each scale grounded in manageable resources such as their economic means, bylaws, and relationships. By identifying a gap between the ideal community-led energy pathway and how each spatial scale works, we show that a strategic political process should fill the gap, especially when niche actors try to actualize energy transition under adverse conditions.

The self-biasing effects of ion gel from source and drain electrodes on electrical characteristics of single layer and few layer molybdenum disulfide (MoS2) field-effect transistor (FET) have been studied. The self-biasing effect of ion gel is tested for two different configurations, covered and open, where ion gel is in contact with either one or both, source and drain electrodes, respectively. In open configuration, the linear output characteristics of the pristine device becomes nonlinear and on–off ratio drops by 3 orders of magnitude due to the increase in “off” current for both single and few layer MoS2 FETs. However, the covered configuration results in a highly asymmetric output characteristics with a rectification of around 103 and an ideality factor of 1.9. This diode like behavior has been attributed to the reduction of Schottky barrier width by the electric field of self-biased ion gel, which enables an efficient injection of electrons by tunneling at metal-MoS2 interface. Finally, finite elem...

We fabricated hydrogenated amorphous silicon (a-Si: H) transparent solar cells using ultrathin transparent multi-layered electrodes (TMEs) as rear-side transparent electrodes for building-integrated photovoltaic (BIPV) windows. Each TME included a bottom layer, thin Ag layer, and optoelectronic controlling layer (OCL). The TMEs were experimentally designed to have high transparency and conductance. The fabricated a-Si:H transparent solar cells showed optimal performance with a 6.36% power-conversion efficiency and 23.5% average transmittance (500–800 nm) when TMEs with a thickness less than 160 nm were incorporated. We demonstrated that the reflection color of the cell could be tuned without serious loss of cell efficiency by varying the thickness of the OCL. The backside colors were predicted to be the coordinates on a CIE 1931 chromaticity diagram using the reflection spectrum from the cell and emission spectrum of a 50 W LED light source. The developed a-Si:H transparent solar cells exhibited high efficiency and show feasibility for incorporating various colors in the photovoltaic and aesthetic functionalities of BIPV windows.

HfSe2 field effect transistors are systematically studied in order to selectively tune their electrical properties by optimizing layer thickness and oxygen plasma treatment. The optimized plasma-treated HfSe2 field effect transistors showed a high on/off ratio improvement of four orders of magnitude, from 27 to 105, a field effect mobility increase from 2.16 to 3.04 cm2 V−1 s−1, a subthreshold swing improvement from 30.6 to 4.8 V dec−1, and a positive threshold voltage shift between depletion mode and enhancement mode, from −7.02 to 11.5 V. The plasma-treated HfSe2 photodetector also demonstrates a reasonable photoresponsivity from the visible to the near-infrared region of light.

Uniform and reproducible alignment methods for one-dimensional structures, such as wires, tubes, and fibers are essential for the fabrication of commercial devices. This paper presents an arbitrary alignment-angle control method. The mechanical stretching of arbitrarily aligned fibers can be increased by as much as 120%. Stretchable electrodes that stably maintain their electro-optical properties against large mechanical deformations are essential for the fabrication of wearable electronics. For randomly distributed fibers, fiber-to-fiber contact resistance has a detrimental effect on the carrier transport. The proposed method aligns fibers into a uniform array to reduce the fiber-to-fiber contact resistance between fibers using parallel-aligned bars. The results demonstrate the feasibility of applying the transfer-free alignment method along a specific alignment-angle for fabricating stretchable metal fiber networks. Fibers are aligned directly onto the sample surface by mounting the alignment jig onto the conventional collecting plate. This transfer-free strategy avoids the deformation and overlap of aligned patterns during the conventional transferring process.

The electrical properties of Al 2 O 3 films have been studied as the dielectric materials for electronic devices which require a low leakage current and high breakdown field. In this work, Al 2 O 3 films with various thicknesses (as low as 10⿿30 nm) were deposited onto Si substrates by plasma-enhanced atomic layer deposition (PEALD), and current density⿿ field curves were measured after post-annealing to verify their electrical properties. One thing to note is that, during PEALD, nitrogen gas was introduced to improve the thermal stability of the Al 2 O 3 films. Breakdown field for add-nitrogen Al 2 O 3 of 30 nm-thick film was enhanced from 6 MV/cm to 10 MV/cm as incorporating nitrogen.

An ambipolar dual-channel field-effect transistor (FET) with a WSe2 /MoS2 heterostructure formed by separately controlled individual channel layers is demonstrated. The FET shows a switchable ambipolar behavior with independent carrier transport of electrons and holes in the individual layers of MoS2 and WSe2 , respectively. Moreover, the photoresponse is studied at the heterointerface of the WSe2 /MoS2 dual-channel FET.

The effects of multi-layered p-type microcrystalline (μc-) Si:H windows on the performance of substrate-type amorphous Si:H thin film solar cells on opaque substrates were investigated. The results were well explained in terms of H2-plasma-induced damage (HPID) at the p/i-interface and the near-interface region of the light-absorbing layer. The μc-Si:H was deposited using plasma enhanced chemical vapor deposition in a H2-rich atmosphere. A high microcrystalline volume fraction was obtained with a high H2 dilution ratio, which can cause considerable HPID. Cell efficiency was enhanced with a multi-layered p-type μc-Si:H composed of films with low and high crystalline volume fraction, compared to cells with single-layered μc-Si:H. In the multi-layered p-type μc-Si:H, the low crystalline film was placed on an i-Si:H layer to reduce HPID. The present work demonstrated that HPID was reduced at the p/i-interface and the near-interface region of the light-absorbing layer, and that the quality of the p-type μc-Si:H needs to be a significant consideration to achieve high efficiency.

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have demonstrated superior electrical and optical characteristics and are expected to replace silicon in semiconductor materials. However, in practice the use of TMDCs remains a challenge due to the lack of a suitable method for the large-scale synthesis of TMDCs. Herein we demonstrated a multi-wafer-scale growth method to obtain very uniform and continuous 2D WSe2 films by combining the selenization of the W metal using thermally cracked Se molecules, a metal-agglomeration-suppressed growth technique, and a traveling flow-type reactor. The usefulness of the traveling flow reactor must be attributed to the self-saturated selenization of a very thin W metal precursor film on a large-area substrate. The number of 2D WSe2 layers was easily controlled by varying the thickness of the W precursor. Raman scattering and thickness measurements showed that WSe2 films grew uniformly on three 4-inch Si wafers at once, at both 530 and 600 °C. The average Hall mobility and carrier concentration of 6-nm-thick p-type WSe2 films on the three wafers were 22.8 cm2 V−1 s−1 and 3.69 × 1016 cm−3, respectively. The field effect (FE) transistor with the 6-nm WSe2 channel and SiO2 back gate insulator also showed p-type transfer characteristics. The formation of a WSe2/MoSe2 vertical heterostructure also demonstrated the usefulness of the method proposed herein.

We demonstrate a multilayer palladium diselenide (PdSe2) high-performance photodetector. The photodetector exhibits the photodetectivity of 0.15 × 1010 Jones under laser illumination (λ = 655 nm and power of 0.057 mWmm−2). The negative threshold voltage shift in transfer characteristics upon laser illumination is mainly attributed to the photogating effect. Systematic analysis of experimental data indicates that the photogating effect and space charge limited conduction are simultaneously involved in the conduction mechanism. We observe that the photogenerated current increases logarithmically as the light intensity increases, and it persists (~200 s) even after stopping the illumination. The slow decrease in current was attributed to the trapping of photogenerated charge carriers at the PdSe2/SiO2 interface and the defects in the structure of PdSe2. We also observe a reproducible and stable time-resolved photoresponse with respect to the incident laser power. We believe that this study can be an important source of information and can help researchers to continue to investigate methods that would allow them to maximise the potential of PdSe2 for photodetector applications.

We studied the effect of oxygen plasma treatment on the drain current and photoconductivity of the two dimensional few-layers MoS2 based field-effect transistors (FETs). It was observed that the oxygen plasma can reduce the photoconductivity of MoS2 channel along with variation in the current characteristics. This study shows the contribution of mild oxygen plasma to modulate the photoconductivity of the MoS2 FETs which can have potential in optoelectronic detectors and sensors applications.

A new concept of a tunneling oxide-free nonvolatile memory device with a deep trap interface floating gate is proposed. This device demonstrates a high on/off current ratio of 107 and a sizable memory window due to deep traps at the interface between the channel and gate dielectric layers. Interestingly, irradiation with 400 nm light can completely restore the program state to the initial one (performing an erasing process), which is attributed to the visible light-sensitive channel layer. Device reproducibility is enhanced by selectively passivating shallow traps at the interface using in situ H2 plasma treatment. The passivated memory device shows highly reproducible memory operation and on-state current during retention bake tests at 85 °C. One of the most significant advantages of this visible light-erasable oxide field-effect transistor-based nonvolatile memory is its simple structure, which is free from deterioration due to the frequent tunneling processes, as compared to conventional nonvolatile me...

This work studies hydrogenated amorphous silicon germanium films, deposited by hot wire chemical vapor deposition, to be used as low band gap absorber material in thin film solar cells. Material properties, such as the bonding configurations, the ambipolar diffusion length and the optical band gap, were examined as a function of the substrate temperature and germanium content. Our best materials were incorporated in single junction solar cells with high long-wavelength response and a tandem solar cell with an efficiency of 10.42%.

Electric motors account for 42.9 % (as of 2010) of electricity consumption in the Korean manufacturing sector, which represents 20.9 % of total electric power demand in Korea. Efficient use of motors in the manufacturing sector is therefore essential in controlling electric power demand in Korea. This study analyzes the potential and economic feasibility of reducing electric motor electricity consumption in the Korean manufacturing sector. Presently, Korea only enforces minimum energy performance standards (MEPS) for three-phase induction electric motors rated 200 kW or less, and the industrial electricity price is much lower than the Organization for Economic Co-operation and Development (OECD) average. In addition, load factors of electric motors are generally far below optimal efficiency, and variable-speed drive (VSD) installation rates are lower than in other advanced countries. This study analyzes the amount and cost of reducing electricity consumption under each of the following scenarios, modeled as additional strategies to the current MEPS, for reducing energy consumption: (1) expansion of MEPS enforcement, (2) increasing the industrial electricity price, (3) enhancement of motor load factors, and (4) installation of VSDs. This study found that increasing the industrial electricity price has the largest electricity reduction potential and is economically most beneficial to the society.

The fractions of various functional groups in graphene oxide (GO) are directly related to its electrical and chemical properties and can be controlled by various reduction methods like thermal, chemical and optical. However, a method with sufficient controllability to regulate the reduction process has been missing. In this work, a hybrid method of thermal and joule heating processes is demonstrated where a progressive control of the ratio of various functional groups can be achieved in a localized area. With this precise control of carbon-oxygen ratio, negative differential resistance (NDR) is observed in the current-voltage characteristics of a two-terminal device in the ambient environment due to charge-activated electrochemical reactions at the GO surface. This experimental observation correlates with the optical and chemical characterizations. This NDR behavior offers new opportunities for the fabrication and application of such novel electronic devices in a wide range of devices applications including switches and oscillators.

Based on newspaper content analysis, the Korean press (2007-08) accepts the anthropogenic argument?that humans have caused and are responsible for climate change. News articles stress the ecological effects of climate change and the need to mitigate and to reduce emissions through government policies. Compared to other countries, however, one point stands out?the Korean press frames mitigation as an economic opportunity, not a threat. Moreover, businesses cited in the news strongly support this idea. However, citing government and business sectors, the conservative and financial newspapers tend to define this opportunity as selling Korean nuclear power technology and green technology abroad. These papers rarely represent voices that advocate structural change in Korean society to reduce its emissions. This particular stance on mitigation as an economic opportunity results from the vulnerability of the Korean export economy to international pressures, coupled with government and business attempt to find a viable export option under the mitigation rationale.

A scattering matrix (S-matrix) analysis method was developed for evaluating hydrogenated amorphous silicon (a-Si:H)-based thin film solar cells. In this approach, light wave vectors A and B represent the incoming and outgoing behaviors of the incident solar light, respectively, in terms of coherent wave and incoherent intensity components. The S-matrix determines the relation between A and B according to optical effects such as reflection and transmission, as described by the Fresnel equations, scattering at the boundary surfaces, or scattering within the propagation medium, as described by the Beer-Lambert law and the change in the phase of the propagating light wave. This matrix can be used to evaluate the behavior of angle-incident coherent and incoherent light simultaneously, and takes into account not only the light scattering process at material boundaries (haze effects) but also nonlinear optical processes within the material. The optical parameters in the S-matrix were determined by modeling both a 2%-gallium-doped zinc oxide transparent conducting oxide and germanium-compounded a-Si:H (a-SiGe:H). Using the S-matrix equations, the photocurrent for an a-Si:H/a-SiGe:H tandem cell and the optical loss in semitransparent a-Si:H solar cells for use in building-integrated photovoltaic applications were analyzed. The developed S-matrix method can also be used as a general analysis tool for various thin film solar cells.

a-Si:H translucent solar cells with various n/i- buffer layers were fabricated. We employed single buffer and double buffers with different thickness in the fabrication of translucent cells. Compared to the cell without n/i- buffers, cell efficiency increases from 5.7% to 6.5% when double buffer layers were used. For further increase of cell efficiency for translucent cells, a backside mirror that reflects the transmitted light was installed and re-absorption of the reflected light was feasible. Interestingly, it was revealed that the thin double buffered cell was the most effective configuration, acquiring approximately 21% higher efficiency. Proper design of optical thickness and arrangement of buffer layers is required to effectively utilize incident and reflected light.

We used very thin (i.e., ~115-nm-thick) absorbers to fabricate full-penetration (FP) semitransparent a-Si:H solar cells for building-integrated photovoltaic (BIPV) windows and introduced high-bandgap (HB) n/i-interface layers to decrease shunt loss and increase carrier collection. The optoelectronic properties of the fabricated cells showed that the HB layers improved the fill factor by decreasing shunt loss and increased the short-circuit current density by enhancing generated-carrier collection. We used scattering matrix analysis to simulate the transmittance characteristics of the semitransparent solar cells fabricated using the HB layers and showed that the HB layers shifted the transmission peak to longer wavelengths. We used a figure of merit (FOM), the product of the efficiency and the average transmittance in the range 400–800 nm, to represent the performance of the semitransparent solar cells and compared the FOMs of the cells fabricated for application to BIPV windows. The cell fabricated using triple HB layers showed the highest FOM, more than 20% higher efficiency than the reference cell (fabricated without using any HB layers), and its transmittance was similar to that of the reference cell. Fabricating FP semitransparent a-Si:H solar cells with triple HB layers and evaluating their optoelectronic performances will be very useful for implementing high-performance BIPV windows.

This paper is concerned with the social responsibility of experts in the fields of science and technology in the process of large-scale nature-transforming national projects. This paper took the case of the Four Major Rivers Restoration Project in Korea?which has been admired internationally as a Korean-style Green New Deal on the one hand, and has caused domestic controversies especially among experts on the other hand?in order to deal with the issue of experts’ social responsibility. The research questions raised in this paper include why and how experts should take social responsibility and to what extent they have to be responsible. Through exploration of the case of the Four Major Rivers Project, this paper argues that experts have to claim social responsibility when national policies and projects are associated with scientific and technological elements, since these events hugely impact the daily lives of the public and the condition of the environment and demand large investments of public money. It also underscores the necessity of having socially responsible experts reveal their values and stances based on verifiable evidence and giving the public a chance to determine which set of experts are working for the public good. Experts should be allowed to contest their arguments and positions under conditions where free speech is respected so they can practice social responsibility. Whether this is allowed or not can reveal the level of democracy of a society. The Four Major Rivers Project identifies the importance of experts’ social responsibility and the conditions for its realization.

We investigate the characteristics of thin films deposited through the addition of gas. The addition of gas has remarkable effects on the phase changes, resulting in improved electrical and optical properties. An intermediate phase () appears at a flow rate of 1 sccm, and a (200) phase is then preferentially grown at a higher feeding amount of . The optical and electrical properties of thin films are improved with a sufficient flow rate of more than 15 sccm, as confirmed through various analyses. Under this condition, a high bandgap energy of 2.58 eV and a conductivity of S/cm are obtained. These high-quality thin films are expected to be applied to -based heterojunction solar cells and optical functional films.

The roughness development of Ag film was investigated for potential as a back reflector material in thin film solar cells on flexible stainless steel (STS) substrates. The influence of metal underlayers was evaluated in order to obtain a rough Ag film at a low deposition temperature (≤400 °C). By depositing Ag on a 100 nm Al underlayer to induce Ag–Al alloying, the film roughness was increased three times more than that of Ag films on bare STS at 400 °C. The Ag film deposited on an Al underlayer at 350 °C exhibited 75 nm roughness and uniformly distributed crystallites, which was effective for visible light scattering. The Ag–Al alloy phase was also controlled using the thickness ratio of Ag and Al. The present work clearly demonstrated that an Ag back reflector film with a higher roughness could be fabricated through inserting a metal underlayer at a deposition temperature much lower than the 500 °C that has been reported in earlier works.

To investigate semi-transparent solar cells, a-Si:H and a-SiGe:H thin film cells have been prepared. In a fabrication of a-Si:H solar cell, top transparent conductive oxide (TCO) thicknesses were varied and the cell with TCO thickness of 300 nm or more exhibited cell efficiency around 5.5%. In particular, a-Si:H cell with 300 nm thick TCO shows average transmittance of visible light around 21.7%, which also shows high efficiency as well. In this experiment, the efficiency and the transmittance did not show a trade-off as is usually observed with conventional semi-transparent solar cells, which is meaningful to control them independently. The a-SiGe:H solar cell with 500 nm thick TCO showed an efficiency of 5.93% and an average transmittance of 17.9%. In spite of its lower transmittance compared to the a-Si:H cell, it can be favorably applied to semi-transparent solar cells.

We investigated penetration-type semi-transparent hydrogenated amorphous silicon (a-Si:H) solar cells that incorporated cuprite (Cu2O) thin films, deposited by radio frequency magnetron sputtering, as the color-adjusting layer. Depending on the arrangement of the Cu2O and transparent conductive oxide layers in the cells, the cells could be classified as either inner-type or outer-type. By simulating and experimentally measuring the reflectance of both types of cells, it was found that the optical interference in the two cells had a more significant effect on the short-circuit current density than did the thickness of the incorporated Cu2O films. We fabricated a-Si:H cells whose transparency and color could be controlled simultaneously. This technique of fabricating a-Si:H cells that exploit the phenomenon of interference can be used to realize cells that exhibit different colors.

We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tinoxide side of the front anode at 100 mW/cm 2 with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers.

In this work, buffer layers with various conditions are inserted at an n/i interface in hydrogenated amorphous silicon semitransparent solar cells. It is observed that the performance of a solar cell strongly depends on the arrangement and thickness of the buffer layer. When arranging buffer layers with various bandgaps in ascending order from the intrinsic layer to the n layer, a relatively high open circuit voltage and short circuit current are observed. In addition, the fill factors are improved, owing to an enhanced shunt resistance under every instance of the introduced n/i buffer layers. Among the various conditions during the arrangement of the buffer layers, a reverse V shape of the energy bandgap is found to be the most effective for high efficiency, which also exhibits intermediate transmittance among all samples. This is an inspiring result, enabling an independent control of the conversion efficiency and transmittance.

This paper analyzes the energy, environmental and economic influences of three electricity scenarios in Korea by 2050 using the “Long-range Energy Alternatives Planning system” (LEAP) model. The reference year was 2008. Scenarios include the baseline (BL), new governmental policy (GP) and sustainable society (SS) scenarios. The growth rate of electricity demand in the GP scenario was higher than that of the BL scenario while the growth rate in the SS scenario was lower than that of the BL scenario. Greenhouse gas emissions from electricity generation in 2050 in the BL and GP scenarios were similar with current emissions. However, emissions in 2050 in the SS scenario were about 80% lower than emissions in 2008, because of the expansion of renewable electricity in spite of the phase-out of nuclear energy. While nuclear and coal-fired power plants accounted for most of the electricity generated in the BL and GP scenarios in 2050, the SS scenario projected that renewable energy would generate the most electricity in 2050. It was found that the discounted cumulative costs from 2009 to 2050 in the SS scenario would be 20 and 10% higher than that of the BL and GP scenarios, respectively.

Reducing global emissions will require a global cosmopolitan culture built from detailed attention to conflicting national climate change frames (interpretations) in media discourse. The authors analyze the global field of media climate change discourse using 17 diverse cases and 131 frames. They find four main conflicting dimensions of difference: validity of climate science, scale of ecological risk, scale of climate politics, and support for mitigation policy. These dimensions yield four clusters of cases producing a fractured global field. Positive values on the dimensions show modest association with emissions reductions. Data-mining media research is needed to determine trends in this global field., U.S. National Science Foundation (BCS 0827006), Canada Social Sciences and Humanities Research Council (430-2011-0093), Japan Society for the Promotion of Science (Standard Research Grant) (22243036), China National Planning Office of Philosophy and Social Science (Young Scholar Research Grant for Social Science) (11CSH026), PRTLI 5 Higher Education Authority Ireland, Korea Research Foundation Global Research Network Grant (MEST) (KRF-2008-220-B00013), Swedish Research Council (2007-2363), Swiss National Science Foundation, and National Science Council of Taiwan

This paper compares and analyzes the contents and sources of news articles on climate change in three major South Korean newspapers between 2007 and 2008. Chosunilbo, Hankyoreh, and Maeil Business were selected as subjects for this study because these three newspapers are representative of the conservative, progressive, and economic newspapers in South Korea, respectively. The key questions asked in this paper are as follows: 1) How do these selected newspapers portray climate change? 2) What kind of sources do they cite, and how do these sources differ? 3) What kind of solutions do the newspapers recommend in dealing with climate change? South Korean press has handled the climate change issue largely from a prognostic frame, placing emphasis on reports concerning policy determination and mitigation policies. The most frequently cited source in all the newspapers was the government. There were differences in the emphasis of each newspaper, however: The conservative newspaper and the business newspaper both supported the policy of sustaining capitalistic economic growth while maintaining existing economic and social structures. The progressive newspaper called for active reduction in the amount of GHG emissions and took a critical position on high-risk and big technologies such as nuclear power generation.

Korea has been one of the most aggressive countries pursuing nuclear power expansion, ranking in the top five nations globally for the installation capacity of nuclear power plants, nuclear power generation, and the number of reactors in operation. Even after the Fukushima accident, the Korean government has made no policy changes in regards to nuclear power, and public support for nuclear power remains relatively high. This study focuses on the role of the mass media in representing the Korean government’s benefit-oriented nuclear frame and the persistence of public support in the country for nuclear power. The study further aims to answer the following questions: What kind of frame was mobilized by the mass media? What kinds of speakers were chosen by the media to represent a particular side to the issue? A total of three conservative, progressive, and business newspapers were analyzed. The benefits and/or risks of nuclear power in the context of climate change were major topics in the three newspapers. The benefit and risk frame constructed in these three newspapers was characterized as “slightly risky but significantly beneficial” in the conservative Chosun Daily and MK Business and “seemingly beneficial but intrinsically risky” in the progressive Hankyoreh. Different frames were contested in the three newspapers; however, because the influential power of Korean progressive newspapers is weak, arguments supporting the growth and benefits of nuclear power have become pervasive in Korea.

Random plasma treatment techniques were used as a texturing method to reduce the surface reflection of glass substrates in thin film solar cells. Various gas mixtures were used for the plasma discharge in an effort to examine the texturing mechanism. Using a plasma treatment comprising CF4/O2 and CF4/Ar with a gas flow ratio of 1 to 2, the surface reflectance could be decreased to 6.83% and 6.82%, respectively. The surface treatment was very effective with the use of a low RF power of 50 W and an optimal time of 5 min. It is considered that the optical characteristics of the glass substrate are highly correlated to its surface morphology which can be produced not only through nano-scale chemical reactions with radicals but also through ion flux bombardment.

Amorphous SiGe:H (a-SiGe:H) single junction solar cells having light absorbing layers with different Ge profiles were fabricated to investigate the effects of the Ge composition profiles on the solar cell performance. The structures of a-SiGe:H layers were characterized by (a) a constant Ge composition (18%), (b) a stepwise Ge composition, (c) a gradually decreased Ge composition profile (18 ~ 0%), and (d) a complex Ge profile, respectively. The cell performances were compared on the bases of current density – voltage characteristics curves and external quantum efficiency. Among the samples, cell (c) with a gradually decreased Ge profile showed the best performance.

A graphene-MoS2 (GM) heterostructure based diode is fabricated using asymmetric contacts to MoS2, as well as an asymmetric top gate (ATG). The GM diode exhibits a rectification ratio of 5 from asymmetric contacts, which is improved to 105 after the incorporation of an ATG. This improvement is attributed to the asymmetric modulation of carrier concentration and effective Schottky barrier height (SBH) by the ATG during forward and reverse bias. This is further confirmed from the temperature dependent measurement, where a difference of 0.22 eV is observed between the effective SBH for forward and reverse bias. Moreover, the rectification ratio also depends on carrier concentration in MoS2 and can be varied with the change in temperature as well as back gate voltage. Under laser light illumination, the device demonstrates strong opto-electric response with 100 times improvement in the relative photo current, as well as a responsivity of 1.9 A W−1 and a specific detectivity of 2.4 × 1010 Jones. These devices can also be implemented using other two dimensional (2D) materials and suggest a promising approach to incorporate diverse 2D materials for future nano-electronics and optoelectronics applications.

Molybdenum disulfide (MoS2) based field effect transistors (FETs) are of considerable interest in electronic and opto-electronic applications but often have large hysteresis and threshold voltage instabilities. In this study, by using advanced transfer techniques, hexagonal boron nitride (hBN) encapsulated FETs based on a single, homogeneous and atomic-thin MoS2 flake are fabricated on hBN and SiO2 substrates. This allows for a better and a precise comparison between the charge traps at the semiconductor-dielectric interfaces at MoS2−SiO2 and hBN interfaces. The impact of ambient environment and entities on hysteresis is minimized by encapsulating the active MoS2 layer with a single hBN on both the devices. The device to device variations induced by different MoS2 layer is also eliminated by employing a single MoS2 layer for fabricating both devices. After eliminating these additional factors which induce variation in the device characteristics, it is found from the measurements that the trapped charge density is reduced to 1.9 × 1011 cm−2 on hBN substrate as compared to 1.1 × 1012 cm−2 on SiO2 substrate. Further, reduced hysteresis and stable threshold voltage are observed on hBN substrate and their dependence on gate sweep rate, sweep range, and gate stress is also studied. This precise comparison between encapsulated devices on SiO2 and hBN substrates further demonstrate the requirement of hBN substrate and encapsulation for improved and stable performance of MoS2 FETs.

Gallium-doped zinc oxide (GZO) films were studied using rf-magnetron sputter deposition technique for the use of transparent conducting oxide film. The effects of deposition parameters such as pressure, rf-power, and film thickness on electrical and optical characteristics of GZO films were evaluated to obtain transparent conducting film with high transmittance and low resistivity for a-Si:H thin film solar cells. The resistivity and the structural properties of GZO film strongly depended on rf-power density and film thickness. The 1200 nm-thick GZO film deposited at 15 mTorr and 150 °C with rf-power density of 4.46 W/cm2 showed the resistivity as low as 6.2 × 10−4 Ω cm and the average transmittance of 86.5% in visible light wavelength region of 400–800 nm.