Atomic-layer-deposited zinc oxide as tunable uncooled infrared microbolometer material

ZnO is an attractive material for both electrical and optical applications due to its wide bandgap of 3.37eV and tunable electrical properties. Here, we investigate the application potential of atomic-layer-deposited ZnO in uncooled microbolometers. The temperature coefficient of resistance is observed to be as high as -10.4%K-1 near room temperature with the ZnO thin film grown at 120 degrees C. Spectral noise characteristics of thin films grown at various temperatures are also investigated and show that the 120 degrees C grown ZnO has a corner frequency of 2kHz. With its high TCR value and low electrical noise, atomic-layer-deposited (ALD) ZnO at 120 degrees C is shown to possess a great potential to be used as the active layer of uncooled microbolometers. The optical properties of the ALD-grown ZnO films in the infrared region are demonstrated to be tunable with growth temperature from near transparent to a strong absorber. We also show that ALD-grown ZnO can outperform commercially standard absorber materials and appears promising as a new structural material for microbolometer-based applications

İşlevsel nanoplazmonik aygıtlar ve yeni fotonik malzemeler

Cataloged from PDF version of article.Plasmonics is one of the pillars of nanophotonics involving light matter interactions. Its applications found very wide range covering photovoltaics, photodetection, optical communication, surface enhanced infrared absorption and Raman spectroscopy, infrared and THz imaging. Although the number of applications is very high, the underlying plasmonic structures are limited. In this thesis, we utilize a common plasmonic resonator structure namely metal-insulator-metal (MIM resonators) to realize active beam steering in the infrared spectrum. We investigate radiation characteristics of a phased array antenna formed by MIM resonators. Materials-wise, low intrinsic loss, CMOS compatibility and bio-compatibility are among the crucial requirements for various applications of plasmonics. Noble metals are the dominant materials used in plasmonics to get high localization of the incident field among which gold and silver face serious challenges due to high intrinsic loss and lack of CMOS compatibility. We introduce InN as a novel plasmonic material thanks to its high concentration of free carriers and investigate its optical characteristics in the IR spectrum. We form a proof-of-concept absorber and investigate its plasmon excitation characteristics. On the other hand, we introduce another material ZnO, nonplasmonic, suitable for infrared imaging purposes with strong absorption characteristics. Optical modulators are at the very heart of active light manipulation technologies such as integrated optics, bio-sensing, telecommunications, radio frequency and terahertz applications. Although various modulation schemes have been realized, the underlying mechanisms providing modulation did not change significantly. The common modulation methods can be listed as free carrier dispersion, thermo-optic method, use of liquid crystals, magneto-optical, optically nonlinear materials and recently introduced solid-state phase-change materials. Here we introduce another mechanism called resistive switching for optical modulation in the infrared spectrum. We investigate electrical resistive switching characteristics of an Al/ZnO/Si stack and optical modulation characteristics under electrical bias. We obtain hysteretic modulation in the reflection spectrum. We also investigate the thermo-optic modulation characteristics of atomic layer deposited ZnO through spectroscopic ellipsometry and realization of actively reconfigurable reflector surface.Battal, EnesM.S

Change of family in the process of urbanization: A field research in Bursa

"Kent" ve "aile" insanlık tarihinin iki önemli olgusudur. Kent, sosyal olarak heterojen bireylerin oluşturduğu, büyük ve yoğun bir yerleşim birimidir. Aile ise, kan, yasa ve evlilik yoluyla, birbirlerine akrabalıkları bulunan hane halkı üyelerinden meydana gelen sosyal bir kurumdur. Aileye, birincil ilişkiler, kente ise, ikincil ilişkiler yön vermektedir. İnsanların kırsaldan kent merkezlerine akın etmesi sonucu, kentlerin nüfus ve alan yönünden büyümesi ise, "kentleşme" olarak adlandırılmaktadır. Kentleşme aynı zamanda, insanların kentte örgütlenme biçimini ifade eden, bir toplumsal değişme sürecidir. Bu bağlamda kentleşme, toplumsal bir kurum olan aileyi de etkilemekte ve değişimine sebep olmaktadır. Çalışmanın ana hipotezi, bu düşünce üzerine kurulmuştur.Sosyal bilimlerde alan çalışması yapılmadan, sadece literatür bilgisiyle özgün ve gerçekci sonuçlar çıkarabilmenin mümkün olamayacağı düşünülmektedir. Bu nedenle çalışma; kentleşme sürecinde ailede meydana gelen değişmeleri, bir alan araştırması çerçevesinde ele almaktadır. Bursa'da yapılan bu araştırma, kır ve kent merkezinde yaşayan aileleri karşılaştırmalı olarak incelemektedir.Çalışmada veri toplamak için yüzyüze anket, görüşme ve gözlem teknikleri kullanılmaktadır. Çalışmanın birinci bölümünde kentleşme, ikinci bölümünde ise aile konusu, ayrıntılı bir şekilde ele alınmaktadır. Üçüncü bölümde, kentleşme ve aile arasındaki ilişki, toplumsal değişme ve modernleşme kavramları çerçevesinde incelenmektedir. Dördüncü bölümde ise, alan araştırmasının sonuçları yorumlanmaktadır."City" and "family" are the two important phenomenon in the history of mankind. The city is a large and dense settlement composed of socially heterogeneous individuals. On the other hand, the family is a social institution consists of household members who become relatives through blood and marriage laws. Primary relationships give direction to the family whereas secondary relationships give direction to the city. The growth of the city in terms of population and area as a result of the influx of the people from rural to urban centers is called "urbanization". Urbanization is also a process of social change that represents how people are organized in the city. In this context, urbanization affects and causes the change of family as a social institution. The main hypothesis of this study is based on this very idea. It is assumed that it is not possible to reach original and realistic conclusions only by doing bibliographical survey but not field research in social sciences. Therefore, this study deals with the changes in the family in the process of urbanization within the framework of a field research. The research conducted in Bursa, comparatively examines the families living both in rural and urban centers. In order to collect data; one-on-one interview, conversation, and observation techniques are used in the study. The first part of the study deals with the urbanization whereas family issue is dealt in the second part of the study. In the third part, the relation between urbanization and family is examined within the context of social change and modernization concepts. In the fourth part, the results of the field research are interpreted

Plasmonic materials based on ZnO films and their potential for developing broadband middle-infrared absorbers

Noble metals such as gold and silver have been extensively used for plasmonic applications due to their ability to support plasmons, yet they suffer from high intrinsic losses. Alternative plasmonic materials that offer low loss and tunability are desired for a new generation of efficient and agile devices. In this paper, atomic layer deposition (ALD) grown ZnO is investigated as a candidate material for plasmonic applications. Optical constants of ZnO are investigated along with figures of merit pertaining to plasmonic waveguides. We show that ZnO can alleviate the trade-off between propagation length and mode confinement width owing to tunable dielectric properties. In order to demonstrate plasmonic resonances, we simulate a grating structure and computationally demonstrate an ultra-wide-band (4–15 μm) infrared absorber

Bursa Kent Konseyi’nin Bilinirliğinin Araştırılması(Investigation of Bursa City Council Awareness)

Türkiye’de 2005 yılında yürürlüğe giren Belediye Kanunu, yönetişim yaklaşımı doğrultusunda sivil toplum örgütlerinin, meslek teşekküllerinin ve kentteki diğer aktörlerin karar ve uygulamalarda yer alabilmesi amacıyla “Kent Konseyleri” uygulamasını getirmiştir. Bu yasa doğrultusunda 2006 yılında Kent Konseyleri Yönetmeliği yürürlüğe girmiştir. Bu çerçevede kent konseylerinin kurulması; Türkiye’deki b Belediyeler için bir zorunluluk haline gelmiştir. Bu çalışmada Türkiye’de ilk kurulan kent konseylerinden birisi olan Bursa Kent Konseyi analiz edilmiştir. 1995 yılında yerel düzeyde çoğulcu ve katılımcı demokrasi ilkelerinin hayata geçirilmesi ve kent sorunlarının demokratik bir platformda tartışılması amacıyla Bursa Büyükşehir Belediyesi’nin girişimiyle “Şehir Danışma ve Dayanışma Konseyi” oluşturulmuştur. Konsey, 1998 yılında yeniden yapılanarak “Bursa Kent Konseyi” platformuna dönüşmüştür. Bu çalışmada Bursa kentinde yaşayan kişilerin Kent Konseyleri ve Bursa Kent Konseyi hakkındaki bilgi düzeylerinin tespit edilebilmesi amacıyla bir saha çalışması gerçekleştirilmiştir. Yüz yüze anket tekniğinin kullanıldığı ve 2915 kişi ile görüşmenin gerçekleştirildiği saha çalışmasından çıkan sonuçlardan hareketle Türkiye’de kent konseylerinin daha bilinir ve etkin olabilmeleri yönünde önerilerde bulunulmuştur. The Municipality Law enacted in 2005, has bought the "City Councils" application towards governance approach with the aim of having the civil society organizations, professional establisments and the other actors in the city take part in the decisions and prectices. In accordance with this Law The City Councils Regulation entered in to force in 2006. In this context, the establisment of the City Councils has become an obligation for the municipalies in Turkey. In this study, Bursa City Council which is one of the first city council estalished in Turkey has been analyzed. In 1995, "City Counceling and Solidarity Council" was established with the initiative of Bursa Metropolitan Municipality towards the aim of implementation of pluralistic and participatory democratic principles at the local level and discussion of urban issues in a democratic platform. The Council has become "The Bursa City Council" platform by being restructured in 1998. In this study, a field study has been performed in order to identify the level of knowledge of the people living in the city of Bursa about the City Councils and the Bursa City Council. Departing from the results obtained from the field work in which face-to-face survey tecnique has been used and interview with 2915 people has been carried out, recommendations have been made towards making the city councils in Turkey more familiar and effective

Broadband absorption enhancement in an uncooled microbolometer infrared detector

This paper introduces a method for a broadband absorption enhancement in the LWIR range (8-12 µm), in single layer microbolometer pixels with 35 μm pitch. For the first time in the literature, this study introduces a very simple and low cost approach to enhance the absorption by embedding plasmonic structures at the same level as the already existing metallic layer of a microbolometer pixel. The metal layer comprises the electrode and the arm structures on the body. Even though the periodicity of the plasmonic structures is slightly disturbed by the placement of the electrodes and the connecting metal, the metal arms and the electrodes compensate for the lack of the periodicity contributing to the resonance by their coupling with the individual plasmonic resonators. Various plasmonic structures are designed with FDTD simulations. Individual, plasmonically modified microbolometer pixels are fabricated, and an increase in the average absorption due to surface plasmon excitation at Au/Si3N4 interfaces is observed. Plasmonic structures increase the average absorption from 78% to 82% and result in an overall enhancement of 5.1%. A good agreement between the simulation and the FTIR measurement results are obtained within the LWIR range. This work paves the way for integration of the plasmonic structures within conventional microbolometer devices for performance enhancement without introducing additional costs

A Plasmonically Enhanced Pixel Structure for Uncooled Microbolometer Detectors

This paper introduces a method of broadband absorption enhancement that can be integrated with the conventional suspended microbolometer process with no significant additional cost. The premise of this study is that electric field can be enhanced throughout the structural layer of the microbolometer, resulting in an increase in the absorption of the infrared radiation in the long wave infrared window. A concentric double C-shaped plasmonic geometry is simulated using the FDTD method, and this geometry is fabricated on suspended pixel arrays. Simulation results and FTIR measurements are in good agreement indicating a broadband absorption enhancement in the 8 µm-12 µm range for LWIR applications. The enhancement is attained using metallic geometries embedded in the structural layer of the suspended microbridge, where the metallic-dielectric interface increases the average absorption of a 35 µm pixel from 67.6% to 80.1%. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

An analysis for the broad-band absorption enhancement using plasmonic structures on uncooled infrared detector pixels

This paper introduces an analysis on the absorption enhancement in uncooled infrared pixels using resonant plasmon modes in metal structures, and it reports, for the first time in literature, broad-band absorption enhancement using integrated plasmonic structures in microbolometers for unpolarized long-wave IR detection. Different plasmonic structures are designed and simulated on a stack of layers, namely gold, polyimide, and silicon nitride in order to enhance absorption at the long-wave infrared. The simulated structures are fabricated, and the reflectance measurements are conducted using an FTIR Ellipsometer in the 8-12 m wavelength range. Finite difference time domain (FDTD) simulations are compared to experimental measurement results. Computational and experimental results show similar spectral reflection trends, verifying broad-band absorption enhancement in the spectral range of interest. Moreover, this paper computationally investigates pixel-wise absorption enhancement by plasmonic structures integrated with microbolometer pixels using the FDTD method. Special attention is given during the design to be able to implement the integrated plasmonic structures with the microbolometers without a need to modify the pre-determined microbolometer process flow. The optimized structure with plasmonic layer absorbs 84 % of the unpolarized radiation in the 8-12 m spectral range on the average, which is a 22 % increase compared to a reference structure with no plasmonic design. Further improvement may be possible by designing multiply coupled resonant structures