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Stress-induced damage in a MOSFET can be cured by Joule heating, which can be produced by an intentional forward junction current ( ${I}_{\textbf {FWD}}$ ). This curing effect can be further enhanced by the simultaneous application of gate biasing, which does not influence the ${I}_{\textbf {FWD}}$ . A MOSFET was intentionally degraded by harsh hot-carrier injection (HCI) then the damage was cured and nearly returned to its pristine state. The improved self-curing effect was quantitatively verified using low-frequency noise (LFN) analyses. Self-curing by internal heat from the ${I}_{\textbf {FWD}}$ more effectively cured the HCI damage than a nonself-curing using external heat from a hot chuck.

Low-frequency noise (LFN) characteristics under OFF-state stress (OSS), which degrade device performance, were investigated in n-channel MOSFETs. The power spectral density (PSD) was analyzed by investigating the LFN and the border traps located in the gate oxide were extracted along a depth direction perpendicular to the silicon (Si) channel surface. The holes generated by band-to-band tunneling (BTBT) in the overlap region between a drain and a gate were found to be more detrimental to device performance than channel hot-carriers created by impact ionization.

The turn-around effect of drain linear current (Idlin) with stress time in a pMOSFET in the off-state stress is investigated. The degradation rate of Idlin increases to a maximum of 6.1% at 20 s of the stress time and then continuously decreases to 3.35% at 1000 s in the off-state stress. The turn-around effect is analyzed by comparing the degradation rates of the performance parameters (Idlin, Idsat, SS, and Vth) in the off -state and gate induced drain leakage (gidl) -state stress modes. The results indicate that the Idlin turn-around effect in the off-state stress, which occurs as an effect of the negative oxide charge (Qox) formation, is more significant than that of the interface trap (Nit) for short stress time (before 20 s), and the donor-like Nit formation has major effects compared to those of Qox over a long stress time (after 20 s). This observation shows that the stress-induced trap generation can be investigated even if the protection diode exists and critically impacts the drain current degradation and should be seriously considered in the reliability of a DRAM circuit.

The gate-induced drain leakage (GIDL) current is one of the major leakage sources in a dynamic random-access memory (DRAM) cell transistor. In addition to band-to-band tunneling (BTBT), which causes GIDL in the gate-to-drain overlap region, the generation of interface traps in the gate dielectric increases the GIDL current by trap-assisted two-step tunneling (TATT). In this article, the influence of OFF-state stress on the generation of the interface traps, which deteriorates GIDL, was quantitatively analyzed with charge pumping (CP) characterization method in buried-channel array transistors (BCATs) for DRAM cells. The applied stress increased the GIDL current while simultaneously degrading device performance including such as transconductance ( $\text{g}_{\text {m}}$ ) and ON-state current ( ${I}_{ \mathrm{\scriptscriptstyle ON}}$ ), due to the generation of the interface traps. By using the CP characterization, the interface traps were spatially profiled along the gate-to-drain overlap region in the junction. Trap distribution inside the energy bandgap was also characterized.

Spatial visitation patterns and its features on nature-based tourism are difficult to assess using only a field-based survey, which is costly and labor intensive. However, understanding of a protected area's visitation status is critical, as it can strongly influence the sustainability of natural resources. Hence, it is important to identify ‘where people visit’ and ‘why people visit,’ to evaluate the features attractive to tourists. In this regard, we proposed and applied social big data to investigate nature-based tourism in an ASEAN Heritage Park. Overall, our research was able to effectively illustrate spatial patterns of visitation using 10 years of Flickr geo-tagged photographs. Hotspots of high visitation were identified, while revealing the local spatial impact of distributed attributes. This study offers insights into the applicability of social big data to protected-area management and its potential in reinforcing existing field-based participatory approaches.

There is an increasing need for spatial planning to manage coastal tourism, and applying social media data has emerged as an effective strategy to support coastal tourism spatial planning. Researchers and decision-makers require spatially explicit information that effectively reveals the current visitation state of the region. The purpose of this study is to identify coastal tourism hotspots considering appropriate spatial units in the regional scale using social media data to examine the advantages and limitations of applying spatial hotspots to spatial planning. Data from Flickr and Twitter with 30″ spatial resolution were obtained from four South Korean regions. Coastal tourism hotspots were then derived using Getis-Ord Gi. Comparing the derived hotspot maps with the visitation rate distribution maps, the derived hotspot maps sufficiently identified the spatial influences of visitors and tourist attractions applicable for spatial planning. As the spatial autocorrelation of social media data differs based on the spatial unit, coastal tourism hotspots according to spatial unit are inevitably different. Spatial hotspots derived from the appropriate spatial unit using social media data are useful for coastal tourism spatial planning.

우리나라 해양오염방제정책은 1995년 씨프린스호 기름유출사고와 2007년 허베이 스피리트호 기름유출사고 대응을 겪으며 체계화되었다. 그러나 2010년 미국에서 발생한 딥워터 호라이즌(Deepwater Horizon) 사고는 최근 해양오염사고 트렌드 변화에 따른 우리나라 해양오염방제 정책 개선 필요성을 일깨워 준 계기가 되었다. 미래에는 해양오염사고 발생 지역이 원해와 해중·해저로 확대되고, 경질유, 가스 및 위험·유해물질 등 해양오염물질 종류가 늘어날 것으로 보인다. 기후변화에 따른 극한기상 증가로 사고도 자주 발생할 것으로 보인다. 또한 자연재난이 해양오염사고와 합쳐진 복합재난이 임해산업단지에서 발생하고, 해양오염사고에 따른 생태적, 사회경제적 피해도 증가할 것이다. 그러나 국가 해양오염방제 정책은 업무 범위와 법제도, 장비 및 기술개발과 의사결정 지원체계 측면에서 긴급방제 및 해상 기름유출에 한정되어 있다. 해양오염방제 의사결정 과정에 민간 참여도 부족했다. 따라서 본 연구에서는 국가 해양오염방제 정책 개선 방안으로 5가지를 제안하였다. 첫째, 해양오염방제 업무 범위를 복합재난 대처, 새로운 오염물질 대응, 기후변화와 생태계 영향 요인 저감으로 확대한다. 둘째, 관련 법제도 개정사항으로 해양오염사고 대응을 위한 업무영역 및 해양경찰청의 역할과 임무를 확대한다. 셋째, 전천후 대응이 가능한 방제 장비 및 기술을 개발한다. 넷째, 생태계와 사회경제적 민감 자원 영향을 저감할 수 있도록 해양오염방제 의사결정 지원체계를 개선한다. 다섯째, 과학적 의사결정을 위한 민간 전문가 참여를 확대하고, 국내 해양오염방제 산업 육성을 위해 아시아 지역에 특화된 박람회나 국제학술대회를 개최하며, 이해관계자의 인식 증진을 위한 방제 정보를 공개한다.

This study is to provide guidance for selecting sites suitable for offshore wind farm developments with lower social, economic, and environmental impacts in the South Korea southwest coastal area with its complicated shoreline configuration, large ecologically important tidal flats, and various marine-based human activities. To analyze the economic feasibility of offshore wind farms, harvestable energy was calculated using an InVEST (Integrated Valuation of Environmental Services and Tradeoffs) model that has been used widely for marine ecosystem service analysis. Capital costs for grid connection and electricity transmission, operation and maintenance costs, and other costs were integrated together to calculate a net present value (NPV) of a 60-MW offshore wind farm assuming a lifetime of 20 years of operation. It is important to note that NPVs of offshore wind farms are affected significantly by the proximity to the closest inland substations, showing the importance of grid connection. Criteria that may cause social and environmental conflicts were grouped into three categories: nature conservation and landscape protection, marine-based human activities, and marine environment and marine ecosystem. Available datasets for each category were compiled and incorporated into GIS-based maps. Many social and environmental criteria overlapped spatially, and areas influenced by one or more criteria were designated as areas of potential conflicts. Economic analysis results and potential social and environmental conflicts were considered together to select areas that could produce wind energy more efficiently with minimum social and environmental conflicts. Economic, social, and environmental assessment strategies and procedures provided in this study can be used as an effective decision-making support tool to find sites for offshore wind farm development and various other offshore developments as well.

Deuterium (D2) annealing was applied to a poly-crystalline silicon thin-film transistor (poly-Si TFT) to improve reliability and performance. The field-effect electron mobility ( $\mu $ ) was extracted using the gate transconductance ( ${g}_{m}$ ) method. It was found that $\mu $ was improved before and after D2 annealing. The interface trap density ( ${D}_{\text {it}}$ ) as well as the oxide trap density ( ${N}_{\text {ot}}$ ) in the poly-Si TFTs was quantitatively extracted using both conventional dc I–V characterization and analysis of low frequency noise ( LFN ). The profile of ${N}_{\text {ot}}$ along the depth direction was investigated before and after D2 annealing using LFN characteristics. It was confirmed that ${D}_{\text {it}}$ as well as ${N}_{\text {ot}}$ was reduced by the D2 annealing, resulting in a reduction in power spectral density and variation.

Multi-gate transistors, such as double-gate, tri-gate and gate-all-around transistors are the most advanced Si transistor structure today. Here, a genuine double-gate transistor with a graphene channel is experimentally demonstrated. The top and bottom gates of the double-gate graphene field-effect transistor (DG GFET) are electrically connected so that the conductivity of the graphene channel can be modulated simultaneously by both the top and bottom gate. A single-gate graphene field-effect transistor (SG GFET) with only the top gate is also fabricated as a control device. For systematical analysis, the transfer characteristics of both GFETs were measured and compared. Whereas the maximum transconductance of the SG GFET was 17.1 μS/μm, that of the DG GFET was 25.7 μS/μm, which is approximately a 50% enhancement. The enhancement of the transconductance was reproduced and comprehensively explained by a physics-based compact model for GFETs. The investigation of the enhanced transfer characteristics of the DG GFET in this work shows the possibility of a multi-gate architecture for high-performance graphene transistor technology.

2010년 미국 멕시코만에서 발생한 딥워터 호라이즌 사고 이후 세계적으로 기름유출 연구 경향이 급변하고 있다. 따라서 본 연구는 지금까지 발표된 국내외 기름유출 관련 논문을 토대로 기름유출 연구 경향을 비교하였다. 분석 결과 전체 논문 수는 시간 흐름에 따라 국내외 모두 증가하였으나, 2014년부터 국내 논문은 감소 추세를 보였다. 국외의 경우 학문분야별로는 일정 패턴을 유지하였으나, 국내는 시간 변화에 따라 학문 비중이 변하였다. 국내외 모두 주요 유출사고에 따라 연구지역 비중이 급변하였지만, 유출량이 연구량을 대변하진 않았고, 상대적으로 적게 연구된 지역이 있었다. 연구 결과를 토대로 국내외 기름유출 연구 갭(gap)을 분석한 결과, 앞으로 우리나라에서는 1) 발생 빈도가 높고 소규모인 기름유출 및 동해 지역 연구, 2) 기름유출에 따른 지역주민과 방제작업자의 건강 영향 연구, 3) 우리나라 해양 및 연안 환경과 생태계에 미치는 기름유출 영향 연구가 필요한 것으로 분석되었다.

A highly biased linear current method (HBLCM) for separately extracting source and drain resistance ( ${R}_{S}$ and ${R}_{D}$ ) in MOSFETs is proposed. The technique can be applied to a single device by using simple modeling. Compared to other methods, it provides accurate values of ${R}_{S}$ and ${R}_{D}$ because it considers carrier mobility degradation. The method basically uses linear current versus gate voltage ( ${I}_{\text {DS}} - {V}_{\text {GS}}$ and ${I}_{\text {SD}} - {V}_{\text {GD}}$ ) characteristics before and after the source/drain interchange ( ${I}_{\text {DS}}$ and ${I}_{\text {SD}}$ ). Afterward, by using the traditional Y-function and subsequent resistance modeling in a highly biased linear condition, ${R}_{S}$ and ${R}_{D}$ can be separately extracted. In order to evaluate and verify the accuracy of HBLCM, an external resistor was intentionally connected to a source electrode of a device, and the resulting change in source resistance was detected using the proposed method. Moreover, to demonstrate an application of the proposed method, internal resistance deliberately created by hot-carrier injection (HCI) was linked to a drain electrode, thereby changing drain resistance. The changed drain resistance was also sensed by the HBLCM. Afterward, the HCI-stressed device was cured by electrothermal annealing driven by Joule heating, and the recovery was again clearly observed using the proposed method.

Achieving high sensitivity in solid-state gas sensors can allow the precise detection of chemical agents. In particular, detection of volatile organic compounds (VOCs) at the parts per billion (ppb) level is critical for the early diagnosis of diseases. To obtain high sensitivity, two requirements need to be simultaneously satisfied: (i) low electrical noise and (ii) strong signal, which existing sensor materials cannot meet. Here, we demonstrate that 2D metal carbide MXenes, which possess high metallic conductivity for low noise and a fully functionalized surface for a strong signal, greatly outperform the sensitivity of conventional semiconductor channel materials. Ti3C2Tx MXene gas sensors exhibited a very low limit of detection of 50–100 ppb for VOC gases at room temperature. Also, the extremely low noise led to a signal-to-noise ratio 2 orders of magnitude higher than that of other 2D materials, surpassing the best sensors known. Our results provide insight in utilizing highly functionalized metallic...

The higher heat load in urban areas than that in rural areas increases the heat stress of citizens and cooling load. Ecosystem-based planning can be a cost-effective solution for cooling cities. In this study, we quantified and mapped the cooling services of multiple ecosystems based on sensible heat mitigation effects and their energy saving potential during the hottest time of the day. Forests, grassland, water bodies, and swamps were considered in this study, and we identified the most efficient ecosystems in the study area with low cooling services. Water bodies exhibited the highest cooling service by mitigating the sensible heat flux by up to 250 W/m2. However, forests made the greatest contribution due to their higher area ratio than that of water. These ecosystems can reduce the energy requried for air-conditioning during the hottest time of the day by approximately 0.15 kWh/m2. The cooling service quantifying and mapping methods proposed in this study can help urban planners to develop more sustainable and resilient cities that can more efficiently incorporate ecosystem-based cooling services.

A physical unclonable function (PUF) device using a nano-electromechanical (NEM) switch was demonstrated. The most important feature of the NEM-switch-based PUF is its use of stiction. Stiction is one of the chronic problems associated with micro- and nano-electromechanical system (MEMS/NEMS) devices; however, here, it was utilized to intentionally implement a PUF for hardware-based security. The stiction is caused by capillary and van der Waals forces, producing strong adhesion, which can be utilized to design a highly robust and stable PUF. The probability that stiction will occur on either of two gates in the NEM switch is the same, and consequently, the occurrence of the stiction is random and unique, which is critical to its PUF performance. This uniqueness was evaluated by measuring the interchip Hamming distance (interchip HD), which characterizes how different responses are made when the same challenge is applied. Uniformity was also evaluated by the proportion of "1" or "0" in the response bit-string. The reliability of the proposed PUF device was assessed by stress tests under harsh environments such as high temperature, high dose radiation, and microwaves.

The importance of the reliability of gate oxide materials is increasing continuously as CMOS technology advancing. Joule heating to induce localized high temperature via a built-in gate heater has recently been introduced as a rapid and efficient method to cure instances of gate oxide damage, including damaged interface traps and bulk traps in the gate oxide. In this paper, spatially distributed deep oxide traps were generated by Fowler–Nordheim (FN) stress, and a recovery process by electrothermal annealing (ETA) using local Joule heat was clearly demonstrated with low-frequency (LF) noise characteristics. The generation and recovery of the oxide traps were quantitatively analyzed with LF noise, and the results showed that the border traps generated by the FN stress were cured by ETA. The recovery process was predominantly affected by the applied gate voltage and the duration. Excessive gate voltage beyond the critical value permanently destroyed the gate oxide. The effect of a forming gas annealing (FGA) process on the gate oxide traps was also analyzed with LF noise and compared with that of ETA. Although electrical Joule heating was applied under a condition of ambient air, not hydrogen-rich atmosphere, the passivation effect was superior to that of a FGA process conducted in diluted H2 ambient.

The self-heating effects (SHEs) in gate-all-around (GAA) MOSFETs with vertically stacked silicon nanowire (SiNW) channels are investigated. Direct observations using thermal images, electrical proof measurements, and supportive numerical simulations are carried out to verify the SHEs. This paper examines the location of hot spots as well as heat dissipation paths (heat sink) depending on the device geometry, and the electrical degradation produced by the SHEs. It also includes the estimation of the surface temperature of the GAA MOSFET and the average temperature across the bulk channel. Design parameters for improved management of the heat dissipation in a device are suggested. This investigation can contribute to improve the device performance and reliability of a 3-D stacked structure.

Aluminum oxynitride (AlON) is investigated as a germanium oxide (GeO) desorption barrier layer for Ge MOSFETs. Interface and border traps in the AlON/GeO2/Ge gate-stack are discussed in detail and compared with those in the Al2O3/GeO2/Ge gate-stack via MOS and MOSFET structures. Although the interface traps remain the same for AlON and Al2O3 in the gate stacks, the AlON gate-stack exhibits a reduced border trap, which results in improved reliability over the Al2O3 gate-stack. This is supported by both the charge-trapping and low-frequency noise analyses.

The low-frequency noise (LFN) characteristics of a vertical pillar-type FET were investigated in order to observe the different influences of the source resistance ( $R_{S})$ and the drain resistance ( $R_{D})$ . Because of its inherent vertical channel structure, the $R_{S}$ and $R_{D}$ are inevitably different. To observe the effects of the asymmetric $R_{S}$ and $R_{D}$ on LFN, a forward mode (FM) and reverse mode (RM) of voltage sweep were used. In the RM, the correlated mobility fluctuation effect was higher and the power spectral density of resistance fluctuation ( $S_{\mathrm{ RSD}})$ was lower than those in the FM. In addition, $S_{\mathrm{ RSD}}$ was correlated with the $R_{S}$ , but little with the $R_{D}$ . To suppress $S_{\mathrm{ RSD}}$ , it is important to minimize the $R_{S}$ .

Amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) fabricated by low-temperature processes on a flexible substrate can easily be degraded by mechanical deformation. Furthermore, lower performance in terms of the initial characteristics and reliability levels compared to those fabricated on glass substrates with relatively high heat treatments is inevitable. To solve these problems, a local electro-thermal annealing (ETA) method was applied to flexible a-IGZO TFTs processed at low temperature to enhance the inferior initial characteristics and reliability under a bending state. The enhancement of the characteristics and reliability by ETA can be attributed to the reduction of defects related to the oxygen through a localized Joule heat treatment with an extremely short duration (~1 ms). In addition, the effectiveness of ETA to recovery from bending stress even under harsh cyclic bending operation (strain condition of 0.833%) is verified.

Nickel germanide (NiGe) was formed from atomic layer deposition (ALD) Ni on Ge and a subequent annealing process; the Ni film with low resistivity ( $34~\mu \Omega \cdot \text {cm}$ ) at 15 nm was obtained by N2 + H2 plasma treatment after Ni precursor injection. The formed NiGe film showed low specific contact resistivity ( $\rho _{c})$ values of 9.01 $\mu \Omega \cdot \text {cm}^{2}$ for an NiGe/n+Ge contact and 3.61 $\mu \Omega \cdot \text {cm}^{2}$ for an NiGe/p+Ge contact. These values were comparable to those obtained using sputtered Ni. In addition, the ALD process-based NiGe showed excellent thermal/electrical stability up to 600 °C.

In this response, we show that the paper by Kim et al. by our group has a different research purpose and uses different modeling processes, which was not described in the previous work by Ortiz-Conde et al. The comments issued by Ortiz-Conde et al., who claim that our paper corresponds to a particular case of their previous work, are in our opinion overgeneralized. Differences compared to Ortiz-Conde’s previous work are discussed in detail. We also explain how the problem on threshold voltage pointed out by Ortiz-Conde et al. can be solved through a semiempirical method from measured data.

In countries and regions where development projects are frequently implemented, there is a significant change in the value of carbon sequestration services according to land use and land cover (LULC) changes. In this study, we analyzed the changes in the carbon sequestration services which occurred due to the LULC changes over a 20 years period (1989–2009) in Korea where local development projects have been active, since 1990s. As a result, the total carbon stocks decreased by about 0.07 billion t C. Significant changes in the carbon stocks mostly occurred in areas where development projects were frequently implemented. The loss of economic value due to the changes in carbon stocks over 20 years was 4.7 trillion won (4159 million USD) when market price of carbon is applied. Therefore, in countries and regions where there is an active development, it is necessary to monitor the land-use changes with high carbon stocks, to reconsider the value of the carbon when making policy decisions which cause LULC changes, and to internalize social costs into the market prices. Especially at a local level, it is necessary to promote management policy based on carbon sequestration services in accordance with local conditions such as size and types of the changes in carbon stocks.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Low-frequency (LF) noise in a vertically stacked nanowire (VS-NW) memory device, which is based on the silicon–oxide–nitride–oxide–silicon (SONOS) configuration is characterized in two different operational modes, an inversion-mode and a junctionless-mode (JM). The LF noise showed 1/ $f$ –shape behavior regardless of the operational mode and followed the carrier number fluctuation model. With regard to the device-to-device variation and quality degradation of the LF noise after iterative program/erase operations, the five-story JM SONOS memory showed comparatively high immunity arising from its inherent bulk conduction and no-junction feature. Despite the harsh fabrication condition used to construct five-story VS-NW, even the five-story JM SONOS memory exhibited LF noise characteristics comparable to those of one-story JM SONOS memory. Thus, the five-story JM SONOS memory is attractive due to its high-performance capabilities and good scalability.

An electro-thermal annealing (ETA) method, which uses an electrical pulse of less than 100 ns, was developed to improve the electrical performance of array-level amorphous-oxide-semiconductor (AOS) thin-film transistors (TFTs). The practicality of the ETA method was experimentally demonstrated with transparent amorphous In-Ga-Zn-O (a-IGZO) TFTs. The overall electrical performance metrics were boosted by the proposed method: up to 205% for the trans-conductance (gm), 158% for the linear current (Ilinear), and 206% for the subthreshold swing (SS). The performance enhancement were interpreted by X-ray photoelectron microscopy (XPS), showing a reduction of oxygen vacancies in a-IGZO after the ETA. Furthermore, by virtue of the extremely short operation time (80 ns) of ETA, which neither provokes a delay of the mandatory TFTs operation such as addressing operation for the display refresh nor demands extra physical treatment, the semipermanent use of displays can be realized.

Erbium carbide (ErC2) prepared by atomic layer deposition (ALD) is successfully demonstrated for the first time as a novel work function (WF) metal for nMOSFET applications. The prepared ErC2 shows a very low effective WF (eWF), as low as 3.9 eV on HfO2, yet with excellent thermal stability. In addition, it did not show significant Fermi-level pinning on high- $k$ dielectrics even after high-temperature annealing. The low eWF property of ErC2 originates from the properties of the lanthanide family, while its good thermal stability is attributed to the properties of metal carbides. ALD-ErC2 has superior conformality over other deposition methods, and thus is a strong candidate for 3-D structure devices.

Low-frequency noise (LFN) behaviors, characterized with an SONOS-based gate-all-around junctionless nanowire (JLNW), are investigated to determine the suitability of this type of NW as a memory cell structure. LFN exhibits a 1/ $f$ -shape and is described by a carrier number fluctuation noise model. It is found that the proposed device structure shows a low level of device-to-device variation and high immunity against Fowler–Nordheim tunneling stress. Due to the centered conduction path in the JLNW device, the impact of correlated mobility fluctuations on the LFN is insignificant. The trapped charge in the nitride layer of the Silicon(Poly-Si)-oxide(SiO2)-nitride(SiN x )-oxide(SiO2)-silicon(Single-crystalline) (SONOS) device also negligibly influences the LFN. The NW width-dependence is clarified in terms of the effects of the oxide trap density and source/drain series resistance under a fresh and a programmed state.