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Yüksek verimli perovskit güneş hücresi elde etmek için pin hole içermeyen, ince, yüksek şeffaflı, mükemmel taşıyıcı ayırma kabiliyetine sahip, üretimi kolay elektron transfer tabakasına (ETL) olması gereklidir. ETL malzemesi olarak hem kompakt (c-TiO2) hem de mezo (mp-TiO2) yapılı olarak kullanılabilen TiO2’dir. Bu çalışmada üretilen ETL, c-TiO2’in sol-jel yöntemiyle hazırlanmış 2000, 2500, 3000, 3500 ve 4000 rpm beş farklı döneme hızlarında döndürülerek kaplama yöntemiyle kaplanmıştır. Kaplanan incefilmlerden perovskit güneş hücreleri için en ideal kalınlıkta, pin hole içermeyen aktif kristalli elektron transfer tabakası belirlenerek SEM, XRD ve profilometre yardımıyla karakterize edilmiştir.

Karbon atomlarının hekzagonal örgüde bir araya gelerek oluşturduğu tek atom kalınlığındaki grafen son yılların en yoğun araştırılan konularından bir tanesi olmasının yanı sıra yüksek elektrik ve ısı iletkenliği, yüksek ışık geçirgenliği, yüksek dayanım ve geniş yüzey alanı gibi birçok üstün özellikleri ile geniş bir yelpazede kullanım alanına sahiptir. Bu üstün özelliklere karşın grafenin sahip olduğu yüksek tabak direnci ve yasak enerji aralığının olmaması grafenin optoelektronik uygulamalarda kullanımını sınırlamaktadır. Grafenin bu dezavantajları grafen yapısına yapılan katkılamalarla aşılabilmektedir. Ancak, katkılı grafen sentez sürecince katkıcı seçimi ve sentez yöntemi çok önemli olmakla birlikte özellikle katkılamanın kalıcılığı ve homojenliği daha değerlidir. Bu çalışmada CVD sistemi kullanılarak bakır folyo üzerinde katkısız ve nitrojen katkılı grafen sentezi ve karakterizasyonu gerçekleştirilmiştir. Katkılı grafen sentezi için piridin kullanılmış olup, piridin hem karbon hem de nitrojen kaynağı olarak kullanılmıştır. CVD tekniğinin kullanımı hem homojen hem de kalıcı katkılama gerçekleştirilebilmesine imkan vermiştir. Çalışma kapsamında ayrıca piridine ek olarak sentez sırasında CVD sistemine düşük miktarda metan gaz akışı sağlanarak film kalınlığı optimize edilmiştir. Katkılı filmlerin karakterizasyonu kapsamında Raman spektroskopisi, Enerji Dağılımlı X-ışını spektroskopisi ve X-ışını foto elektron spektroskopisi teknikleri kullanılmış olup, film kalitesi, kalınlığı, homojenliği, katkılama oranı ve türü belirlenmiştir.

This study aims to examine the effectiveness of different methods by comparing the academic achievement levels of jigsaw groups in the subjects they are experts in and in those they are not experts in. The sample of the study, which was carried out with a pretest posttest experimental design without a control group, consisted of 24 middle school students, 15 boys and 9 girls. A 20-question “science, technology and society achievement test” was used as the data collection tool. The test included 5 questions about each of the 4 topics of expertise assigned to the groups. The achievement that had a reliability coefficient of 0.85 was applied in the jigsaw groups as the pretest and the posttest. Since the data did not show a normal distribution, Wilcoxon Signed-Rank Test and Kruskal-Wallis test were used for the analyses. In the analysis, the Mann-Whitney U test with Bonferroni correction was used to determine which groups had significant differences. The results showed that using the jigsaw II method increased the academic achievement of the students in all dimensions of the test. However, a significant difference was found between the success levels of the jigsaw groups in the dimensions of the test. This result showed that students are more successful in their assigned subjects than other subjects.

This study draws on our experiences with graphene to perform a hybrid TCO structure composed of AZO and graphene. We first set out to enhance the electrical and optical properties of AZO to enable its use especially in the field of solar cell. Hence, in our study, we deposited various thicknesses of AZO thin films on glass substrates and transferred single layer graphene on them to realize the formation of hybrid TCO structure. Among the various AZO film thicknesses, the optimum one, 300 nm, was determined and then the graphene film was added on top of the AZO film. This hybrid structure was applied to the silicon-based heterojunction solar cell with the idea of improving the cell performance. The cell performance fabricated using AZO film and AZO + graphene structure was analyzed using solar simulator. Our findings highlight the fact that the presence of graphene improved the cell efficiency by about 7%. Our research was further extended using ITO and ITO + graphene hybrid structure as TCO for silicon-based solar cell. We discovered that graphene incorporation increased the cell efficiency by almost 12% based on our results with ITO + graphene hybrid TCO structure on a similar cell.

Koronavirüs (COVID-19) salgını sebebiyle Türkiye dahil birçok ülkede, 2019-2020 eğitim-öğretim yılının bahar döneminde, örgün eğitimden uzaktan eğitime geçilmiştir. Bu dönemde sosyal mesafeyi koruma önlemleri kapsamında sokağa çıkma yasakları uygulanmıştır. Acil olarak başlatılan uzaktan eğitim, öğretim yöntem ve uygulamalarının değişmesine sebep olmuştur. Salgın sürecinin uzun sürmesi, öğrenmeye ayrılan zamanı ve öğrencilerin öğrenme fırsatlarını sınırlandırmıştır. Araştırmanın amacı sosyal bilgiler öğretmen adaylarının salgın sürecinde uzaktan eğitim deneyimlerini ve bu sürece ilişkin görüşlerini almaktır. Durum çalışması şeklinde tasarlanan araştırma Türkiye’deki yedi farklı üniversiteden 151 öğretmen adayının katılımı ile gerçekleştirilmiştir. Yarı yapılandırılmış görüşme formu ile elde edilen veriler içerik analizi çözümlenmiştir. Araştırma sonuçları, salgın sürecinde yapılan uzaktan öğretimde öğretmen adaylarının, internete erişim, materyal temini, öğrenme ortamı sağlama, öğrenme güçlüğü vb. sebeplerden zorluklar yaşadıklarını göstermiştir. Aynı zamanda uzaktan öğretim sürecinin zamandan ve mekândan bağımsız öğrenme, araştırma, okuma ve öğrenme becerilerini geliştirme gibi faydalarının olduğunu da ortaya koymuştur.

The aim of this study is to reveal the experiences of social studies teachers and prospective teachers in developing augmented reality applications and their views on the use of this technology in social studies teaching. The sample of the study consists of 60 people, including a total that 30 social studies teachers working in different cities of Turkey and 30 prospective teachers studying in the social studies education departments of 10 different universities. The data obtained by the questionnaire were analyzed by descriptive statistical methods. As a result of the research, participants evaluated the use of augmented reality technology in social studies teaching as innovative, flexible, effective, entertaining and interesting. It was stated that the use of augmented reality applications in social studies courses would create an effective learning environment and multimedia teaching. They also stated that some limitation factors such as accessing the internet, connection speed and providing class discipline in the use of augmented reality applications in the classroom.

In this study, CZTS thin films were grown by annealing of sputtered films using quaternary single target employing various annealing parameters. The effects of the post-sulfurization treatment, reaction temperature (500, 525, 550 and 575 degrees C) and sulfurization time (60, 90, 120 and 150 s) on the properties of CZTS thin films were analyzed. The optimization of reaction temperature for 60 s dwell time was examined by annealing the precursor films with/without sulfur atmosphere. It was shown that annealing of the films under the sulfur atmosphere prevents Zn-loss in the samples for higher annealing temperatures (550 and 575 degrees C) and hindering the formation of secondary phases such as Cu2-xS, Cu2SnS3(CTS). The FWHM values of the sulfurized samples revealed that the sulfurization temperature of 550 degrees C is preferable for the fabrication of CZTS samples. Further optimization was performed at 550 degrees C for various sulfurization times. It was seen that all the samples have Cu-poor and Zn-rich composition. The XRD pattern of CZTS samples displayed formation of kesterite CZTS phase but SnS(2)phase formations were also observed for longer sulfurization time (> 120 s). It was also observed that the sulfurization time has more significant contribution on the crystallite size of the samples with respect to sulfurization temperature. The Raman spectra of the CZTS samples confirmed the formation of kesterite structures for all the films and appearance of secondary phase for films prepared using longer sulfurization time (> 120 s). All the samples displayed a dense and polycrystalline surface morphology, but the sulfurized sample for 120 s displayed more homogenous and prominent morphology. The room temperature PL measurements demonstrated a broad band which peaked at about 1.36-1.37 eV, which is very close to the band gap of kesterite CZTS structure. The electrical characterization of the samples showed that all the samples have p-type conductivity and the CZTS-S-550-120 sample has a more promising result considering both resistivity and carrier concentration.

Finansal okuryazarlık becerisi öğrencilere kazandırılması için 2018 yılında güncellenen sosyal bilgiler öğretim programına eklenmiştir. Finansal okuryazarlık, bireylerin finansal ürünlere ve kavramlara hakimiyeti, finansal risk almaları ve çeşitli alternatifler arasından tercih yapabilecek farkındalığa sahip olmaları sayesinde finansal refahlarını artırma süreci olarak tanımlanmaktadır. Bilgiyi, teknolojiyi ve finans kaynaklarını üreten bir toplum meydana getirmek için de finansal okuryazarlık becerisinin erken yaşlarda bireylere kazandırılması gerekmektedir. Sosyal bilgiler öğretmenlerinin finansal okuryazarlık becerisi hakkında farkındalıklarını tespit etmek ve bu becerinin kazandırılmasına yönelik görüşlerini almak amacıyla yapılan bu çalışmada nitel desen kullanılmıştır. Araştırmanın çalışma grubunu, ulaşılabilen, çalışmaya katılmayı kabul eden ve Rize il ve ilçelerindeki ilk ve ortaokullarda görev yapan 20 sosyal bilgiler öğretmeni oluşturmuştur. Veriler içerik analizi ile değerlendirilmiştir. Araştırma sonuçları öğretmenlerin finansal okuryazarlık becerisinin tanımını ve beceriye ilişkin yeterlilikleri bildiklerini göstermektedir. Ancak bu becerinin öğrencilerde geliştirilmesi için kullanılabilecek etkinlikleri yeterince bilmedikleri ve sınıflarında uygulamadıkları anlaşılmaktadır.

In this study, we investigated the impact of incorporating graphene with Ga-doped ZnO (GZO) when employing them as a TCO layer on Si-based solar cell. GZO thin films with various thicknesses (50-450 nm) were fabricated by the sputtering method using a single target. The aim here was to determine the GZO film with the optimum thickness to incorporate it with single layer graphene as TCO. This thickness was found to be 350 nm as that was the best crystalline quality found in the Opattern. Further, this sample had the lowest sheet resistance and highest transmission values as confirmed by electrical (sheet resistance), and optical characterizations (transmission). Topographic (SEM and AFM), electrical (resistivity and carrier concentration) measurements were also conducted on the same sample. The graphene film grown on copper in a CVD system was then transferred on top of this sample to fabricate the hybrid TCO structure. We found that graphene integrated GZO hybrid TCO film showed higher sheet resistance due to high sheet resistance of graphene and similar optical properties thanks to high optical transmission of graphene. Employing graphene-based TCO layer in the solar cell resulted in higher open-circuit voltage, consequently improving the conversion efficiency from 10.0% to 11.2%. (c) 2021 Elsevier Ltd. All rights reserved.

In this study, Cu2ZnSnS4 (CZTS) thin films were synthesized by a two-stage process. In the first stage, CuSn/Zn/Cu (E-type) and CuSn/ZnS/Cu (B-type) stacked films were formed using the sputtering method. In the second stage, precursor films were annealed in sulfur atmosphere utilizing various annealing temperatures (500, 525, 550 and 575 degrees C) employing the Rapid Thermal Processing (RTP) method. The EDX measurements demonstrated that almost all the samples had Cu-poor and Zn-rich compositions, as targeted. The XRD patterns of all the CZTS samples were dominated by diffraction peaks of the kesterite CZTS phase. In addition to CZTS phase, Cu-S/Sn-S based secondary phases in all E-type CZTS thin films and some B-type CZTS samples annealed at lower temperatures (500 and 525 degrees C) were observed. The samples annealed at above 525 degrees C revealed purer crystal structure in terms of secondary phases and they have more promising crystallite size in both types of CZTS thin films. The Raman spectroscopy measurements confirmed the formation of kesterite CZTS phase and distinguished the formation of Cu2SnS3 (CTS) phase for some samples. The samples annealed at 550 degrees C presented purer structure for potential solar cell application. The SEM surface and cross-section images of all CZTS samples displayed dense and polycrystalline structures but samples annealed at 550 degrees C presented a larger-grained surface and crosssection structure in both types of CZTS films. PL spectra of the B-type CZTS samples exhibited a purer band structure with respect to E type CZTS samples according to their PL band values. The best solar cell performance was achieved with CZTS thin film prepared using CuSn/ZnS/Cu stack annealed at 550 degrees C temperature with 252 mV, 32 mA/cm(2), and 3.79% parameters. (C) 2021 Elsevier Ltd. All rights reserved.

Amongst the silicon (Si)-based photovoltaics, heterojunction solar cells are the most promising solar cells due to their low thermal coefficient, high efficiency, and compatibility with newly emerged materials, such as graphene and perovskite. Studies on Si-based solar cells with graphene have increased dramatically in recent years. Thus far, high power conversion efficiency has been achieved up to 15 % by integrating graphene into graphene/Si Schottky junction solar cells since graphene has excellent electrical and optical properties. This chapter provides an overview of the status of the implementation of graphene into Si-based solar cells and focuses on the integration of graphene to Si heterojunction solar cells as a transparent conductive oxide. The chapter is presented in two parts. The first part reviews and discusses the literature on Si heterojunction solar cells and graphene. The second part contains experimental studies divided into three sections. We discuss photovoltaic parameters and the fabrication of Si-based heterojunction solar cells and underline the advantages and problematic issues in Section I. Section II describes graphene synthesis by chemical vapor deposition, doping, and characterization in detail. The results are discussed in relation to the current literature. Section III is devoted to Si heterojunction/graphene solar cell power conversion efficiency. This chapter concludes with predicting the future direction of high efficiency and low-cost Si heterojunction/graphene solar cells.

Slicing is generally done with multi or single wire slicing systems. Parameters such as slicing speed, wire feed speed, wire tension, size, and density of abrasives are critical production parameters for slicing. Two types of slicing systems in use are conventional inner diameter saws and wire saws. The efficiency of Silicon (Si) solar cell is directly related to perfection of the surface. Surface defects during the preparation of wafer reduce the cell’s efficiency and service life. The slicing operation is a vital process for turning a-Si ingot or block into a wafer, and there is a fifty percent loss of material depending on the slicing system and wire type. The chapter considers obtaining the optimal process parameters of slicing of monocrystalline Si ingot in wafer form. The slicing operation is a vital process for turning a-Si ingot or block into a wafer, and there is almost a fifty percent loss of material depending on the slicing system and wire type.

Cu2ZnSnS4 (CZTS) thin films are commonly used as an absorber layer in the thin film solar cell structure. In this study, CZTS thin films were produced by sulfurization of stacked precursor films that is prepared by deposition of Cu, Zn, SnS, ZnS films on glass substrate using sputtering method. The sequential sputter deposition was performed to obtain two distinct stacked precursors, Cu/SnS/Zn/Cu and Cu/SnS/ZnS/Cu respectively. Afterwards, annealing process was implemented at various reaction temperatures (500–575 °C) for 1 min utilizing rapid thermal processing (RTP). The EDX measurements revealed that all the prepared CZTS samples had Cu-poor and Zn-rich composition that are non-stoichiometric chemical composition. This non-stoichiometric composition is important for high efficient CZTS based solar cells. XRD measurements revealed that all patterns are dominated by diffraction planes of kesterite CZTS. The CuS, Cu2S and SnS2 secondary phases also were detected in the XRD pattern of some CZTS films. Raman spectroscopy measurements verified formation of kesterite CZTS phase for all films and picked out CTS phase for some samples prepared using Cu/SnS/Zn/Cu precursor films. The surface microstructure of the films that were obtained through SEM displayed polycrystalline surface structure. Room temperature PL emission spectra of the films showed broad peak at around 1.37–1.38 eV, which is near to the optical band gap of kesterite CZTS structure. Electrical characterization of the samples demonstrated that B-525 CZTS thin film has more suitable electrical resistivity and carrier concentration values for CZTS based solar cell applications.

Cognitive description and comprehension of the structure, existence and relations of a space and its reflection and restructuring in the mind of a space is called spatial perception. Individuals' perceptions of space change according to their environmental awareness, knowledge and impressions. The ability of individuals to perceive their surroundings, adapt to the places they are in and regulate their lives better depends on the sophistication of their perceptions of space. Spatial skills such as spatial representation, spatial representation, spatial analysis, and spatial evaluation need to be improved. In order to develop the spatial skills. The fact that the features of the space give an idea about how that space can be perceived and the interaction of the individual with the space, it emphasizes out-of-school learning in order to develop of the spatial perception skills. In this study, it is aimed to investigate the effects of the activities of a social studies education project carried out within the scope of TUBITAK 4004 Nature Education and Science Schools Support Program on the perception of spatial skills space and the use of out-of-school spaces in teaching this skill. The study was conducted with a case study, one of the qualitative research types. The study group consisted of 30 prospective teachers selected by criterion sampling. The data obtained by open-ended questionnaire and document analysis were evaluated by content analysis. According to the findings obtained in the study, it shows that the applied activities are effective in teaching the spatial skills and the perception of space. Pre-service teachers stated that they can realize the spaces, objects and assets around them with the activities carried out outside the school and they develop their spatial skills by applying them.

Tek kristalli silisyum (Si) alttaslar uzerine ince a-Si tabakalardan olusan c-silisyum heteroeklem teknolojisi son yillarda fotovoltaik (FV) alaninda bir cok arastirmaci ve bilim adami tarafindan calisilan onemli bir arastirma konusudur. Silisyum heteroeklem gunes hucre teknolojisi, yuksek enerji donusum verimliligi ve rekabetci seri uretim maliyeti ile kendisini ispat etmis ve yeni gelistirilen teknolojileri bunyesine entegre edebilme kabiliyeti ile potansiyelini ortaya koymus bir gunes hucresi teknolojisidir Bu calismada, silisyum heteroeklem gunes hucrelerinin uretim asamalari ve karakterizasyonu detayli bir sekilde calisilmistir. a-Si:H incefilmlerin kalinlik, bant araligi ve tasiyici yasam suresi gibi ozellikleri elipsometre, profilometre ve tasiyici yasam suresi cihazi ile arastirilmis ve optimizasyonu yapilmistir. 6 inc n-tipi c-Si alttas uzerine buyutulen katkisiz ince film tabakali heteroeklem (heterojunction with intrinsic thin-layer, HIT) yapisi ile %19,7 verimli gunes hucresi uretilmistir.

In this study CZTS thin films were fabricated bya two-stage process that sputter deposition of metallic Cu, Zn, and Sn on Mocoated glass substrates and annealing process at 500 °C using various shortdwell times (4, 8, and 12 min) using Rapid Thermal Processing (RTP) approach.The X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy(SEM), Energy Dispersive X-ray Spectroscopy (EDX), and photoluminescence wereemployed to characterize the CZTS samples synthesized employing different sulfurizationtimes. It was observed that all CZTS thin films showed Cu-poor and Zn-richcomposition according to EDX results. XRD patterns displayed formation ofkesterite CZTS and CuS secondary phases. Raman spectra of the films justifiedformation of kesterite CZTS phase for all CZTS thin films and formation of CTSphase, which is difficult to distinguish by XRD pattern of the films for CZTS-8and CZTS-12 samples. SEM images of the films displayed dense, void-free, andinhomogeneous surface structure regardless of the sulfurization time. Theoptical band gap of the films as determined by photoluminescence was found tobe about 1.36-1.37 eV., Bu çalışmada CZTS incefilmler iki-aşamalı yöntem kullanılarak üretildi; Mo kaplı cam üzerine saçtırmayöntemiyle metalik Cu, Zn ve Sn katmanlarının kaplanması ve sonrasında bukatmanlı yapının 500 °C sıcaklık ve farklı kısa sürelerde (4, 8 ve 12 dakika)hızlı ısıl işlem (RTP) yaklaşımı ile tavlanması. Farklı tavlama süreleri ileüretilen CZTS örnekler X-ışını kırınımı (XRD), Raman spektroskopisi, TaramalıElektron Mikroskobu (SEM), Enerji Dağılımlı X-ışını Spektroskopisi (EDX) vefotoluminesans teknikleri kullanılarak karakterize edilmiştir. Üretilen bütünCZTS örneklerin Cu-fakiri ve Zn-zengini kimyasal kompozisyona sahip olduğu veXRD desenlerinde CZTS fazı oluşumun yanında CuS fazının da oluştuğugörülmüştür. Raman spektroskopisi ile hem CZTS fazının oluştuğu doğrulanmışolup hem de XRD ile ayırt edilemeyen CTS fazının oluştuğu tespit edilmiştir.SEM ile elde edilen film yüzey görüntülerinin sülfürleme süresinden bağımsızolarak yoğun, deliksiz ve homojen olmayan bir yapıya sahip oldukları tespitedilmiştir. Fotolüminesans spektrumları ile optik yasak enerji aralığının1.36-137 civarında olduğu belirlenmiştir.

Son yillarin nanoteknoloji alaninda en ilgi cekici ve en yogun arastirilan malzemelerinden bir tanesi olan grafen; yuksek elektrik ve isi iletkenligi, saydamlik ve yuksek dayanim gibi bircok ustun ozellikleri ile opto-elektronikten medikal uygulamalara kadar genis bir yelpazede kullanim alanina sahiptir. Grafen sentezinde en sik tercih edilen yontemlerden biri kimyasal buhar biriktirme teknigi olup, bu teknikte kullanilan gazlar, alt-tas, alt-tas temizligi, sicaklik, buyutme suresi, tavlama suresi, sogutma hizi ve basinc gibi bircok parametre grafen sentezinde etkilidir. Bu parametreler arasinda sentez surecini direkt olarak etkileyen en onemli faktorlerden bir tanesi alt-tas secimi ve bunun temizlenme surecidir. Bu calismada alt-tas olarak bakir tercih edilmis olup, yuzey temizliginin grafen sentezine olan etkisi detayli olarak arastirilmistir. Bu anlamda literaturde bilinen dort farkli yuzey temizleme islemi, grafen sentezinde kullanilan bakir folyolar icin uygulanmis ve elde edilen sonuclar ortaya konmustur. Sonuc olarak alt-tas temizliginde grafen sentezini kolaylastiran ve iyilestiren en etkili yontemlerin HF ile standart temizleme yontemi oldugu belirlenmis ve bu yontemlerle tek katli homojen grafen sentezi gerceklestirilmistir. Diger temizleme yontemleri sonrasi yapilan sentezde genellikle cok katmanli ve homojen olmayan grafen filmler elde edilmistir.

Verimli bir Si-tabanlı güneş hücresi için yüksek geçirgenliğe sahip saydam iletken elektrot kullanmak önemli bir ayrıntıdır. Bu amaçla kullanılan indiyum kalay oksit (İTO) aynı zamanda yansıma önleyici kaplama görevini de yerine getirir. Bu çalışmada, alçak basınç püskürtme (ABP) ve yüksek basınç püskürtme (YBP) yöntemleri ile üretilen farklı malzeme yoğunluklarına sahip iki katmanın bir araya getirilmesi ile oluşturulan yoğunluk modülasyonlu İTO ince filmlerin yansıma önleyici olarak davrandığı ve geçirgenliği düşürdüğü gösterilmiştir. YBP ile elde edilen İTO ince filmin üst tabaka olarak kullanıldığı durumda morfolojisinin daha pürüzlü hale geldiği ve her kalınlık değeri için geçirgenliğin daha yüksek olduğu gözlemlenmiştir. Buna bağlı olarak, bu numunelerde çok yönlü yansımanın daha düşük olduğu gösterilmiştir. YBP-İTO katmanın üzerine sentezlenen nanoyapıların oldukça homojen olması ayrıca bir avantajdır. Sonuç olarak, YBP yöntemi daha kullanışlı bir İTO katmanı üretimi için basit ama etkili bir yöntem olduğunu ispatlamıştır., Having a high quality transparent conductive electrode is one of the critical parameters for high efficient Si-based photovoltaic device. Indium tin oxide (ITO), used for this purpose, also behaves as an anti-reflective coating. In this study, it was shown that the density modulated ITO thin films obtained by the combination of the low pressure sputter (LPS) and high pressure sputter (HIPS) layers behave anti-reflective coating as improve the transmission. The density modulated thin film whose upper layer was grown by HIPS has shown a more porous morphology and lower transmission for all thickness values. Besides, it was also observed that the omnidirectional reflection is lower. Additionally, the more homogenous property of the synthesized silicon nanostructures on HIPS-ITO is another beneficial finding. Thus, HIPS has claimed that it is a simple yet effective way of producing more efficient ITO layer

In this study CZTSe thin film were synthesized by a two-stage process that included sequential sputter deposition of Cu and Sn layers forming a Cu/Sn structure, pre-annealing the Cu/Sn structure at 200–380 °C for some of the samples, sputtering of additional Zn and Cu over the Cu/Sn structure, evaporation of a Se cap forming a Cu/Sn/Zn/Cu/Se precursor film, and exposing the precursor film to high temperature annealing treatment at 550 °C for 15 min to form the compound. The results of the characterization carried out on the compound layers revealed that the phase content, composition and microstructure of these layers changed noticeably depending on whether or not a pre-annealing step was utilized. Although XRD studies suggested presence of secondary phases, especially in the non-pre-annealed samples, the data was dominated by kesterite CZTSe phase reflections. Raman spectra of the films verified the formation of kesterite CZTSe structure and some other phases, which were determined to be SnSe 2 and possibly ZnSe. SEM micrographs showed denser structure in the pre-annealed samples. © 2018 Elsevier Ltd

In this paper, we report on the single layer graphene synthesis to establish the growth conditions and improve the opto-electronic properties that can be employed in silicon based heterojunction solar cells. To do this, the effect of hydrogen and methane flow on the graphene growth on copper foil in a CVD system was investigated. The analyses were conducted by changing either the hydrogen or the methane flow by keeping all the other growth parameters constant. Single layer graphene growth recipe was established in order to have the optimum optical transmission and sheet resistance values via amending the graphene growth conditions. It was found that the sheet resistance values of the single layer graphene should be lowered further to be used as transparent conductive electrode. However, the combination of graphene with indium tin oxide film functioned well as transparent conductive electrode in the silicon based the solar cells. Additionally, the cell efficiency increased by about 10% as a result of incorporating it with the single layer graphene. (C) 2019 Elsevier B.V. All rights reserved.

Electron Microscopy and Analysis Group Conference 2017, EMAG 2017 -- 3 July 2017 through 6 July 2017 -- -- 131297, Heterojunction solar cells composed of hydrogenated amorphous silicon (a-Si:H) and c-Si has been widely studied due to its excellent photovoltaic characteristics. In this study, we studied the structural and optical properties of a-Si:H thin films for heterojunction solar cells by using SEM, TEM and ellipsometry. We found that uniform deposition of a-Si:H thin film on substrate is crucial to reach high solar cell efficiencies. © Published under licence by IOP Publishing Ltd., Hitachi, We would like to acknowledge funding from Turkish Ministry of Development and we would like to thank for the data to HITACHI.

The current work describes a spectroscopic method for determining the electron temperature and electron density in an electron beam generator using argon spectral lines based on a collisional radiative model. Neutral and first‐ionized Ar lines emitted from the electron beam generator are studied experimentally. A collisional radiative code was developed to simulate the Ar (I) and Ar (II) spectral emission and to compare the results with the experimental data for electron density and temperature determination. Ar lines and excited level densities were calculated by solving rate equations using the Gauss elimination method. The argon spectrum is recorded experimentally by superposing two discharges, namely a low pressure DC glow discharge and a high current pulsed discharge. Spectral lines between 350 nm and 950 nm were recorded using an integrated signal technique on a charge‐coupled device. Electron temperature is determined by the relative intensity ratio method of two spectral lines. The relati...

Photoluminescence (PL) spectra of Ga 4 Se 3 S layered single crystals have been studied in the wavelength region of 535–855 nm and in the temperature range of 16–200 K. Two PL bands centered at 572 nm (2.168 eV, A-band) and 652 nm (1.902 eV, B-band) were observed at T = 16 K. Variations of both bands have been studied as a function of excitation laser intensity in the range 0.10–149.92 mW cm −2 . The A-band is attributed to radiative transition from donor level located 0.125 eV below the bottom of conduction band to shallow acceptor level located 0.011 eV above the top of the valence band. The increase of the width of B-band and its quenching with increasing temperature is explained using the configurational coordinate model.

Besides having important hormonal effects, progesterone has depressant and hypnotic effects on the brain. In this study, we compared women in the follicular phase with low progesterone levels and in the luteal phase with high progesterone levels regarding their anesthetic requirements. Twenty patients with menstrual cycle days from 1 to 10 (follicular group) and 20 patients with menstrual cycle days from 18 to 24 (luteal group) were included in the study. Anesthesia was induced with fentanyl and thiopental; relaxation was secured with rocuronium, and anesthesia was maintained with a mixture of nitrous oxide 2 L/min and oxygen 2 L/min plus sevoflurane. The delivered sevoflurane concentration was adjusted to sustain a constant bispectral index value that averaged 46 in both groups. To determine the progesterone levels, blood samples were taken from all patients before surgery. We found that progesterone levels were 0.86 +/- 0.30 ng/mL in the follicular group and 7.48 +/- 3.86 ng/mL in the luteal group. The minimum alveolar anesthetic concentration (MAC)-hour (MAC-h) value of sevoflurane in the follicular group (1.55 +/- 0.18 MAC-h) was significantly larger than in the luteal group (1.3 +/- 0.13 MAC-h) (P0.0001). The sevoflurane requirements were larger in the follicular group during the maintenance phase of anesthesia. In conclusion, high progesterone levels during the luteal phase might be the cause of decreased anesthetic requirement.The aim of this study was to determine the effect of high progesterone levels on anesthetic requirement. We measured progesterone levels before surgery and calculated the sevoflurane dose (MAC-h) required to maintain a constant bispectral index value. The dose of sevoflurane correlated inversely with serum progesterone concentrations.

Growth of CdS0.08Se0.92 nanocrystals embedded in glass is studied through the combinative analysis of optical absorption and photoluminescence (PL) spectroscopy at room temperature. The quantum confinement effect is observed in these structures. Average nanocrystal radii are found to be in the range of 2.3?4.2 nm with the help of a quantized state effective mass theory. Photoluminescence spectra are studied by means of the model of Ravindran et al (1999 Nanostruct. Mater. 11 603). The difference between the energies of the deep trap peak and first exciton peak is found to be ~0.2?0.3 eV. The possible sources of the overall shift in these peaks are also discussed.

GaSe single crystals were N-implanted along c-axis with ion beams of 1014 and 1016 ions/cm2 doses having energy values of 60 and 100 keV. The photoluminescence (PL) spectra of undoped and N-implanted GaSe crystals were measured at different temperatures. The PL intensity was observed to decrease with increasing implantation dose while the FWHM of the exciton peaks increased. In heavily doped crystals, due to the interaction with the radiation induced disorders, the wave vector selection rules are satisfied and an indirect exciton PL band is observed 36 meV below the direct exciton states.

Optical anisotropy of the layer semiconductor GaSe has been studied by photoluminescence (PL) and Fourier Transform Infrared Spectroscopy (FTIR). The PL spectra are dominated by two closely positioned emission bands resulting from the free exciton and the bound exciton connected direct band edge of GaSe. Photoluminescence and transmission spectra of GaSe crystals have been measured for two cases in which the propagation vector k is perpendicular (k ⟂ c) and parallel to the c-axis (k // c). Peak position of the PL emission band and the onset of the transmission have been found to be significantly different for these two cases. This observed anisotropy is related to anisotropic band structure and the selection rules for the optical absorption in layered GaSe. FTIR transmission spectrum is in good agreement with PL results. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

2013’te yenilenen Ortaogretim Kurumlari Yonetmeligi ortaogretimlerde geleneksel olcme araclarina ek olarak ogrencilerin bilissel, duyussal ve psikomotor alanlardaki becerilerini kullanmasini ve gelistirmesini saglayacak performans gorevlerine de yer vermistir. Bu arastirmanin amaci performans gorevlerine iliskin ogrenci goruslerinin belirlenmesi ve degerlendirilmesidir. Arastirmanin orneklemini 2014-2015 egitim yili guz doneminde Trabzon’un Of ilcesinde bulunan iki ortaogretim okulunun 9. siniflarinda okuyan 80 ogrenci olusturmustur. Veriler, tarama ve mulakat formu kullanilarak elde edilmistir. Verilerin analizinde, betimsel analiz ve icerik analizi kullanilmistir. Arastirma sonuclara gore; Ogrenciler performans gorevlerini; performans gorevlerinin rahat ortamda hazirlanmasi, yazili ve coktan secmeli sinavlarin ogrencide stres yaratmasi, yuksek not almalari ve ders ortalamalari yukseltmeleri sebepleriyle yazili sinav ve coktan secmeli sinava gore daha cok tercih ettikleri sonucu bulunmustur. Ogrencilerin yarisina yakini Performans gorevlerinin kendilerini aktiflestirdigini, bilgi ve arastirma becerilerini arttirdigini, calismalarinda daha dikkatli olmalarini sagladigini belirtirmistir. Diger ogrenciler ise performans hazirlama surecinin zor, yorucu, sikici ve kaygi verici oldugu gibi olumsuz duygular ifade ederek yazili sinavlar ve performanslarin coklugunun uzerlerine asiri yuk yukledigi icin zamani yetistirmekte cok zorlandiklarini ifade etmislerdir

Araştırmanın amacı sosyal bilgiler dersinde arşiv belgesi kullanılması etkinliğinin öğretmen adaylarının öğrenmelerine etkisini ve sürece yönelik deneyimlerinitespit etmektir. Çalışma grubunu amaçlı örnekleme yöntemlerinden kolay ulaşılabilir durum örneklemesi ile seçilen 34 öğretmen adayı oluşturmaktadır. Nitel araştırma yöntemlerinden olgubilim (fenomenoloji) deseni ile yürütülen araştırmanın verileri yarı yapılandırılmış görüşme formu ve uygulama dokümanlarından elde edilmiştir. Veriler içerik analizi ve doküman inceleme ile çözümlenmiştir. Araştırma bulguları uygulanan etkinliğin katılımcıların sosyal bilgiler dersinde arşiv belgesi kullanılması konusunda öğrenmelerini olumlu etkilediğini göstermektedir. Sosyal bilgiler dersinde arşiv belgelerinin kanıt olarak kullanılmasının öğrencilere nesnel ve güvenilir bilgi sağlayarak onların bilgi üretmelerine imkân verdiği, öğrencilerin dönemin siyasi, sosyal ve kültürel özelliklerini dikkate almalarını ve objektif bir şekilde değerlendirmelerini sağladığı anlaşılmaktadır. Kavram öğrenmeyi kolaylaştırdığı, öğrencilerde birçok beceri ve değerin geliştirilmesinde etkili olduğu belirlenmektedir. Ayrıca arşiv belgelerinin sosyal bilgiler dersinde kullanılması için kazanım, beceri ve değerlere uygun belge seçilmesi, belgelerin öğrencilerin yaşına, ilgisine göre sadeleştirilip düzenlenmesi gerektiği anlaşılmaktadır.

Bu çalışmanın amacı TÜBİTAK tarafından desteklenen bir bilim ve toplum projesi uygulamalarına katılan öğretmen adaylarının sosyal bilgiler öğretiminde okul dışı eğitimin etkililiği ve kullanılması hakkında görüşlerini belirlemektir. Proje kapsamında uygulanan etkinlikler okul dışı sosyal bilgiler öğretiminde tarihsel çevre, coğrafi mekânlar, kurumlar ve doğanın eğitim amaçlı kullanılmasında öğretmen adaylarına planlama, etkinlik düzenleme ve uygulama aşamalarında gerekli bilgi ve deneyim kazanmalarını sağlayacak şekilde tasarlanmıştır. Çalışma grubu Türkiye’de farklı üniversitelerin eğitim fakültelerinin sosyal bilgiler öğretmenliği bölümlerinde okuyan 30 öğretmen adayından oluşmaktadır. Veriler proje amaçları doğrultusunda geliştirilen yarı yapılandırılmış görüşme formu ve yansıtıcı günlüklerden elde edilmiştir. Verilerin değerlendirilmesi içerik analizi ile yapılmıştır. Elde edilen bulgular uygulanan etkinlikler ile öğretmen adaylarının okul dışı mekânlara yönelik bilgi ve farkındalıkların arttığını göstermektedir. Ayrıca, okul dışı öğrenmenin beceri kazandırma, değer geliştirme ve kavram öğretiminde etkili olduğu tespit edilmektedir.

Si and Ge nanocrystals were formed in alumina matrix by ion implantation and subsequent annealing. The phase separation of the Si nanocrystals was observed using X-ray photoelectron spectroscopy by monitoring Si 2p electrons. During nanocrystal formation with a high temperature annealing Si0 signals corresponding to Si nanoclusters increases while Si4+ signals related to a-SiO2 disappears from the spectrum. The transition from amorphous to nanocrystalline phase for both Si and Ge nanoclusters and the compressive stress exerted on the formed nanocrystals were also studied by Raman spectroscopy. Photoluminescence spectra of the Al2O3 containing nanocrystals were discussed by means of Ti and Cr impurities, as well as F centers. The existence of the amorphous Ge nanoclusters in alumina matrix significantly enhances the light emission of Ti3+ impurities.