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Self-Assembled, Millimeter-Sized TIPS-Pentacene Spherulites Grown on Partially Crosslinked Polymer Gate Dielectric
No full textHere, a highly crystalline and self-assembled 6,13-bis(triisopropylsilyleth ynyl) pentacene (TIPS-Pentacene) thin films formed by simple spin-coating for the fabrication of high-performance solution-processed organic field-effect transistors (OFETs) are reported. Rather than using semiconducting organic small-molecule-insulating polymer blends for an active layer of an organic transistor, TIPS-Pentacene organic semiconductor is separately self-assembled on partially crosslinked poly-4-vinylphenol:poly(melamine-co-formaldehyde) (PVP:PMF) gate dielectric, which results in a vertically segregated semiconductor-dielectric film with millimeter-sized spherulite-crystalline morphology of TIPS-Pentacene. The structural and electrical properties of TIPS-Pentacene/PVP:PMF films have been studied using a combination of polarized optical microscopy, atomic force microscopy, 2D-grazing incidence wide-angle X-ray scattering, and secondary ion mass spectrometry. It is finally demonstrated a high-performance OFETs with a maximum hole mobility of 3.40 cm(2) V-1 s(-1) which is, to the best of our knowledge, one of the highest mobility values for TIPS-Pentacene OFETs fabricated using a conventional solution process. It is expected that this new deposition method would be applicable to other small molecular semiconductor-curable polymer gate dielectric systems for high-performance organic electronic applicationsclose0
고감도 벌집 나노선 BioFETs에 관한 연구
No full textDoctorThe biologically sensitive field-effect transistor (BioFET) is the most promising sensor for ubiquitous healthcare applications due to its advantages such as small size, low power consumption, high-speed response, label-free detection, high sensitivity, high stability, and suitability for mass-production and integration with other electronic systems. Recently, nanowires (NWs) have been used for the channel region of the devices due to the enhanced gate controllability and size compatibility to that of biological molecules for cell and protein studies. In this study, a honeycomb nanowire (HCNW) structure is proposed for highly sensitive BioFETs due to many structural benefits. The HCNW is a structure with repetitive hexagonal nanowire blocks. It has remarkable advantages in three aspects such as structural stability, surface area, and self-optimized current path. First, the HCNW shows superior structural stability due to its outstanding capability in force transferring. Therefore, we are able to fabricate the suspended nanowire structure without additional fabrication techniques and to make the fabrication process free from the stiction problem. Second, the surface area of the HCNWs is higher than that of the conventional straight-line nanowires (SLNWs). Hence, the effective width of the device is increased and the sensitivity in the strong inversion regime is enhanced. Finally, the self-optimized current path enhances the current drivability of the devices as well and suppresses statistical device-to-device variation statistically. For a fair comparison of electrical characteristics between the HCNW and the SLNW BioFETs, both devices were fabricated on the same wafer with a distance of 300 microns. The HCNW BioFETs clearly show enhanced electrical characteristics such as lower threshold voltage, lower subthreshold swing, and higher drain current in the same gate overdrive voltage than those of the SLNW devices. Improved electrical characteristics mainly come from geometrical benefits of the HCNW such as the increased effective width and optimal current path. As a result, these notable characteristics of the HCNW enable higher sensitivity in all operation regimes, caused by lower subthreshold swing in the subthreshold regime and higher transconductance in the strong inversion regime. The above results show that the HCNW structure is very promising for enhancing the device performance and for realizing highly sensitive biosensors. For miniaturization for hand-held applications, an Ag/AgCl pseudo-reference electrode (pRE) was embedded on the wafer. The pREs were fabricated using a combination of conventional microfabrication technique and electrochemical reaction with optimization. The open-circuit potential (OCP) characteristics between the pRE and a commercial reference electrode have been measured in order to evaluate the influence of the pRE potential on the device performance. The embedded pRE shows stable voltage drivability and the potential was insensitive to the hydrogen ion concentration and biological molecule concentration with offset of 6 mV and 1.5 mV for pH and alpha fetoprotein concentration, respectively. Those characteristics are critical for the reference electrodes of biosensors.평균 수명의 증대 및 삶의 질에 대한 관심이 급격히 증가하여 U-health에 대한 요구가 급증하고 있다. 이에 발맞추어 U-health에 사용되는 센서에 대한 연구가 활발히 이루어지고 있다. 많은 센서 중 BioFET(biologically sensitivie field effect transistor)는 소형화에 유리하며, 저전력 소모, 빠른 반응속도, 무표지 검출, 높은 감도, 높은 안정성, 대량생산에 유리하며 전자 시스템에 적용이 수월한 장점을 가지고 있어 U-health용 센서 소자로 각광받고 있다. 최근 BioFET의 채널에 1차원 구조인 나노선을 이용한 연구가 널리 진행되고 있다. 나노선은 고유의 높은 게이트 제어능력으로 센서의 감도를 높일 수 있을 뿐 아니라, 구조체의 크기가 생체물질의 크기와 유사하여 감지시의 외부영향을 최소화 할 수 있다는 장점을 가지고 있다. 나노선 BioFET에 관하여 지속적인 연구가 이루어지고 있으나 나노선의 구조를 이용하여 특성을 증대시키기 위한 연구는 진행된 바 없다. 본 학위 논문에서는 U-health 시스템에 적용할 수 있는 벌집 나노선을 이용한 BioFET의 개발에 대하여 논하였다.xm 벌집 나노선은 정육각형 형태의 나노선이 연속적으로 배열 된 구조로 기존의 직선형 나노선에 비하여 다음의 장점을 가지고 있다. 첫째, 높은 구조적 안정성을 가지고 있다. 이는 나노선 벌집구조의 높은 유연성과 뛰어난 응력 전달능력에 때문이다. 따라서 벌집 나노선은 별도의 공정기술 없이도 3차원 구조의 나노선 채널 제작에 용이하며 직선 나노선에서 발생하는 뒤틀림현상을 방지한다. 둘째, 벌집구조의 표면적은 기존의 나노선에 비하여 넓다. 따라서 구동 전류량을 높일 수 있어 선형 영역에서의 감도에 중요한 인자인 트랜스컨덕턴스를 증대시킨다. 마지막으로 네트워크 구조로 인한 자기 최적 전류경로로 소자의 전류구동능력을 향상시키고 소자간 성능차를 감소시키는 효과가 있다. 벌집 나노선과 기존의 직선형 나노선의 직접적 비교를 위하여 단일 기판상에 300 마이크론 간격으로 소자를 배치하였다. 벌집 나노선 소자는 낮은 문턱전압, 낮은 문턱전압 이하 영역에서의 전류 기울기, 동일 게이트 오버드라이브 전위에서 높은 전류값과 같은 향상 된 전기적 특성을 보였다. 이러한 특성은 벌집 나노선의 넓어진 채널 넓이와 자기 최적 전류경로와 같은 구조적 장점으로부터 얻어진다. 향상 된 소자 특성으로 인하여 소자의 모든 동작영역에서 벌집 나노선 소자가 높은 감도를 보였다. 따라서 벌집 나노선은 고감도 바이오센서에 가장 유력한 나노선 구조이다. 소자의 소형화를 위하여 Ag/AgCl 가상 기준전극을 기판에 집적화하였다. 가상 기준전극은 기존의 반도체 공정 기술과 전기화학 반응을 이용하여 형성되었다. 반응 시간을 달리한 전극의 개방 회로 전위측정을 수행하여 반응 조건 최적화를 수행하였다. 집적화 된 가상 기준전극은 안정적인 전류 구동능력을 보였다. 또한 구동 전위는 수소 이온농도 및 단백질 농도에 영향을 받지 않아 기준전극으로써 우수한 특성을 보였다. 측정 된 전위 오프셋은 수소이온 측정 시 6mV, 알파 태아단백질 측정 시 1.5 mV였다
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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