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Intimate relationships are the focal aspiration for human beings. Romantic relationship education is described as a road map for helping people to find strategies and solutions that fit their context, values and relationship goals. By using evidence-based skills training, people can learn techniques to navigate typical relationship challenges and safely express emotions. Being in a mutually satisfying committed relationship has proven to be associated with many positive outcomes including life satisfaction, physical well-being, better coping with major illness, as well as longer life expectancy and career achievement. Relationship education programs are developed by psychologists in Western countries as a preventive intervention for couples, adolescents and emerging adults before relationships reach crisis stage. There is, however, a lack of empirical studies to examine the effectiveness of relationship education within the Turkish cultural context. The overarching aim of this study is to review the relationship education programs within Turkish and international literature. This study provides an overview of the relationship education, and its scope, and theoretical foundations and also effectiveness of relationship education programs for couples, adolescents and emerging adults. The study further provides cultural, theoretical and practical recommendations for future directions in Turkish relationship education programs.

© 2022 Society for the Study of Emerging Adulthood and SAGE Publishing.For the current study, a grounded theory methodology was utilized to generate a substantive theory that illustrates Turkish emerging adults’ different romantic experiences. The study participants were 25 emerging adults (12 female, 13 male), ages ranging from 19 to 26 years. The data analysis revealed four romantic patterns namely, balanced intimacy, learning intimacy, high-dependent intimacy, and lack of intimacy. The findings of the current study contribute to research on romantic relationship models by suggesting that the romantic self-descriptions, connection with the family and the culture, and meaning of past romantic experiences conjointly generate the four different romantic patterns among emerging adults. Furthermore, results suggest that Turkish emerging adults’ romantic experiences show many developmental similarities with their western counterparts while maintaining unique cultural characteristics.

InxGa1−xAs epitaxial layers with different AsH3 flows have been grown on InP substrate with the MOVPE system. It has been found that AsH3 flow variation affects the In concentration of InGaAs/InP structure because the increment of AsH3 flow increases the In concentration due to the weak bond between In and As. The variation of AsH3 flow during the growth process has affected crystal quality and optical properties of InGaAs epilayer. The optical properties of the structure have been determined by spectroscopic ellipsometry and spectrophotometer. The variation of In concentration has changed the refractive index value of the structure. The thickness of the samples and refractive index values have been obtained by spectroscopic ellipsometry. The obtained findings show that the reflection has been improved with high AsH3 flow resulting from surface quality improvement. In addition, it has been observed that the energy band gap has been decreased as a function of the increment of AsH3 flow because the structure band gap approaches the InAs structure at the high In concentration.

AlN films have been deposited on c-plane sapphire substrates by metalorganic-vapor-phase-epitaxy (MOVPE). The changes in the film structure have been investigated by applying different annealing processes which are exsitu rapid thermal annealing (RTA) and in-situ process after the nucleation-layer (NL). The AlN nucleation-layer grown on sapphire has been annealed face-to-face with ex-situ (RTA) process for 3 min and with in-situ process for 3 h, then pulsed-atomic-layer-epitaxy AlN film has been grown at a high temperature. The samples have been characterized by high-resolution X-ray diffraction, atomic force microscopy, Ultraviolet–visible spectrometry, and Raman scattering to examine the structural properties, surface morphology, and optical properties. The sample annealed with the ex-situ (RTA) process, where rapid diffusion took place, has reached larger grain sizes and the dislocation density has decreased as the grain boundary decreased. Although better crystal quality has been obtained with the ex-situ (RTA) process, it has been observed that the surface roughness of the sample annealed with the ex-situ (RTA) process is higher than that of the sample annealed with the in-situ process. Considering the results, a schematic prediction of the growth process after face-to-face annealing has been proposed. Experimental findings have shown that different annealing processes after growing the AlN-NL have a great effect on the properties of the AlN.

Bu çalışma, psikolojik danışmanlık öğrencilerinin danışman öz-yeterliliklerini yordamada otantiklik ve dünyaya ilişkin varsayımların rolünü anlamak amacıyla gerçekleştirilmiştir. Araştırmanın çalışma grubu, İstanbul'da bulunan iki devlet üniversitesinin Rehberlik ve Psikolojik Danışmanlık Ana Bilim Dalında lisans eğitimi görmekte olan üçüncü (N=123) ve dördüncü (N=195) sınıf öğrencileri oluşturmuştur. Veriler, kişisel bilgi formu, Danışman Öz-Yeterlik Ölçeği, Dünyaya ilişkin varsayımlar ölçeği (iyilik varsayımı alt boyutu) ve Otantiklik Ölçeği kullanılarak toplanmıştır. Araştırma sonucunda, danışman özyeterliliğinin, otantikliğin alt boyutları olan kendine yabancılaşma, dışsal etkiye açıklık ve otantik yaşama ile iyilik varsayımı tarafından yordandığı saptanmıştır.

The free buffer InGaAs/InP structure has been elaborated by Metal Organic Vapor Phase Epitaxy (MOVPE). High indium content is chosen to reduce the bandgap energy of the ternary material with direct bandgap to be promoted for Infrared optoelectronic devices. In this work, the temperature dependent photoluminescence (TDPL) analysis of In-rich InxGa1����� xAs (x = 0.65: S1, x = 0.661: S2, and x = 0.667 S3) samples is of the central focus. The S-shaped behavior recorded at low temperature range in the III-V ternary is quantitatively studied herein by Localized State Ensemble (LSE) model. A comparison between the semi-empirical evolution of luminescence versus temperature and our numerical simulation proves the adequacy of computational details, used in LSE model, in well reproducing the S-shape feature. The numerical simulation well matched with PL spectra proving that the localization phenomenon is stronger when increasing the Indium mole fraction. The clustering effect in In-rich structure seems to be beneficial for enhancing the carrier localization within InxGa1����� xAs by localizing carriers from away extended defects that behave probably as non-radiative centers. This is indicative of the utmost importance of localization phenomenon in trapping carriers within localized states instead of dislocations and defects, owing to clustering of indium atoms.

Achieving high threshold current density and high optical confinement are big challenges in the realization of high-performance aluminum gallium nitride (AlGaN)-based deep-ultraviolet (DUV) laser diode (LD). In this work, compositional Al-grading of AlGaN layers is used to increase the optical confinement factor (OCF), carrier injection efficiency, gain, and emission power of the DUV LD. Compositional grading of waveguides (WGs) layer, electron blocking layer (EBL), and cladding layers (CLs) demonstrated that the device characteristic can be improved. By using compositional Al-grading of AlGaN p-WG, EBL, p-CL along with n-WG and n-CL, 17.4% OCF, 94.4 mW emission power, and 1369 m− 1 gain at 267 nm peak emission wavelength are achieved. These improvements are attributed to the reduced threshold current density as well as using better optical confinement scheme in the DUV LD.

In this study, we aim to eliminate low thermal conductivity and refractive index differences in InP and GaSb based materials, which result in low output power and limited operation wavelength range for VECSELs.

InxGa1−xAs epitaxial layers with different AsH3 flows have been grown on InP substrate with the MOVPE system. It has been found that AsH3 flow variation affects the In concentration of InGaAs/InP structure because the increment of AsH3 flow increases the In concentration due to the weak bond between In and As. The variation of AsH3 flow during the growth process has affected crystal quality and optical properties of InGaAs epilayer. The optical properties of the structure have been determined by spectroscopic ellipsometry and spectrophotometer. The variation of In concentration has changed the refractive index value of the structure. The thickness of the samples and refractive index values have been obtained by spectroscopic ellipsometry. The obtained findings show that the reflection has been improved with high AsH3 flow resulting from surface quality improvement. In addition, it has been observed that the energy band gap has been decreased as a function of the increment of AsH3 flow because the structure band gap approaches the InAs structure at the high In concentration., This work is supported by the Scientific Research Project Fund of Sivas Cumhuriyet University under the project number [M-2021–821].

AlN samples have been grown on sapphire substrate using nucleation layers (NLs) having different growth temperatures. The growth temperature of the NL has been varied over a wide range of temperatures highlight the effects on the quality of the AlN epilayer. The AlN samples have been characterized by high-resolution X-ray diffraction (HRXRD), atomic force microscope (AFM), Raman scattering spectrometer, and spectrophotometer. The obtained results demonstrate the temperature of NL has a direct effect on the quality of the AlN sample and occurs major differences in the quality of structure, surface morphology, and amount of strain in the AlN epilayers. Based on HRXRD measurement results, when the growth temperature of AlN NL is raised to 1075 degrees C, the crystal quality has improved owing to both the density of AlN nucleation islands reduction and the grain size outgrow. However, continuing to increase the growth temperature of the AlN NL layer begins to degrade the quality. In addition, the findings obtained from the Raman measurement demonstrates that the tensile stress can be control through NL growth temperature. Therefore, as can be seen from the characterization results, the growth temperature of AlN NL is important to obtain an AlN sample with high quality.

WOS: 000463693300001, We report the effects of AsH3 (arsine) on morphological, structural, optical and crystalline quality of MOVPE (metal organic vapor phase epitaxy) grown GaAs/Ge heterostructures. AsH3 pre-flow supplied on Ge substrate to have As atoms as a first atomic layer on the surface of Ge substrate. Additionally, the V/III ratio effects of LT-GaAs buffer layer, grown on arsenized Ge substrate, have been analyzed to have reduced APBs (anti-phase boundaries) in the interface between epilayer and Ge substrate. It has been considered that the optimal AsH3 pre-flow duration and V/III ratio of GaAs buffer layer extremely influence the effects of APBs even we have used miss-cut Ge substrate and grown by two-step growth technique to obtain double atomic step. It is shown that without AsH3 pre-flow the surface of GaAs epilayer becomes rougher while it is optically smooth under the longer AsH3 pre-flow. On the other hand, even the surface situation does not change with longer AsH3 pre-flow the structural, optical and crystalline qualities become worse because of the possible presence vacancies of created during the growth. Similar behavior has been observed for the V/III effects of GaAs buffer layer and it has resulted in low full width at half maximum of high-resolution X-ray diffraction and high photoluminescence peak intensity for the optimal V/III ratio.

The impact of thermal surface cleaning on epitaxial AlN thin films grown on sapphire is investigated in this study at various temperatures. The sapphire substrate is cleaned in a hydrogen environment. Structural, optical, and surface morphology properties of the samples are investigated by using high-resolution X-ray diffraction, Raman spectroscopy, UV–visible spectroscopy, and atomic force microscopy, respectively. Because wastes from the surface of sapphire, which begins to decompose after 1200 ◦C, cannot be entirely removed at such a low temperature, grain distribution and grain size in the nucleation layer are impacted. Moreover, when a sapphire is cleaned at a high temperature, the rate of breakdown of oxygen atoms from the surface rises, and islands appear on the surface. Roughnesses on the sapphire surface cause misoriented grains and deteriorated the structure. The surface of the sapphire, which is cleaned at 1245 ◦C, was both sufficiently cleaned and not etched too much, uniformly distributed, and large-sized particles formed in the nucleation layer. Thus, the AlN thin film has grown with high quality in terms of structure, optics, and surface. Experimental results have demonstrated that the insitu thermal cleaning temperature has a critical influence on the properties of the AlN.

AIN is used as a template layer for deep UV (DUV) emitter and detector applications, because of its wide bandgap and high thermal conductivity. In this study, trimethylgallium (TMGa) source is used as surfactant to improve crystal quality and decrease dislocation density (DD) of AlN layers grown on sapphire (Al2O3) substrate surfaces by Metal Organic Vapor Phase Epitaxy (MOVPE) system. TMGa pre-flow time and pre-flow amount that TMGa pre-flow to the nucleation stage are the subjects of two distinct optimization studies. The structural and optical properties of grown AIN are examined by a high resolution X-ray diffractometer (HR-XRD), Raman spectroscopy, and UV–Vis–NIR spectrophotometer, respectively. TMGa pre-flow time and TMGa pre-flow amount determined to obtain high crystal quality AlN epilayers are 2 s and 0.446 × 10����� 5 mol/min, respectively. HR-XRD investigation of these growths yields FWHM values of 159/2718 arcsec and 201/1550 arcsec for the ω (002) and ω (102) scans, respectively.

This paper reports the temperature effects on the optical properties of metalorganic vapour-phase epitaxy (MOCVD) grown c-axis oriented AlN epilayer thin film studied by in-situ high-temperature spectroscopic ellipsometry. The crystal structure and the quality of the grown AlN epilayer film are analyzed using X-ray Diffraction and rocking curve techniques, respectively. Modelling of the ellipsometric data revealed that the uniaxial anisotropic refractive indices of the c-axis oriented film in the directions n‖ and n⊥ increased from 2.50 to 2.59 and 2.32 to 2.37, respectively with the increase in temperature from 223 to 573 K. The thermo-optic coefficients were evaluated to be around 10����� 5. Nano-mechanical characterization of this film showed an average hardness of 19.4 GPa at ambient temperature, which is higher than a-axis oriented AlN film. The average surface free energy of the synthesized film as evaluated from contact angle measurements is reported to be around 36.22 ± 0.64 mN/m. These results are highly relevant for a better understanding of c-axis oriented AlNbased materials in high-temperature ultraviolet optical devices.

This study was conducted in Sivas Cumhuriyet University R & D Center (CUTAM), Sivas Cumhuriyet University Nanophotonic Application and Research Center., In this study, Al2O3 thin films of different thicknesses (50 nm, 100 nm, 150 nm, 200 nm, and 250 nm) were, first, grown using RF magnetron sputtering technique on glass substrate at 30 °C temperature, with 120Wpower value. Then 250 nm ZnO was grown on these thin films. Microstructural analyses of the thin films were made by scanning electron microscope (SEM). It was observed that the particle size changed with increasing thickness of Al2O3 thin films. ZnO layer was grown onto alumina grown tubes with an approximate thickness of 250 nm. The grain morphology of ZnO was similar to alumina, about 25–30 nm grain size. Energy-dispersive X-ray analysis (EDX) detector was used to determine the chemical composition of the samples. These results have indicated that ZnO thin films are successfully formed on alumina tubes. Crystal structure analyses of all samples were examined using the X-ray diffraction (XRD) technique. In addition, the optical properties of the samples were examined with ultraviolet-visible-near infrared spectrometer (UV-VIS-NIR). This work provides valuable references for the application of Al2O3 as insulating buffer layers., This research was supported by Scientific Research Project Fund of Sivas Cumhuriyet University under the project number RGD-32.

teristics of heteroepitaxial Metal-Organic Vapor Phase Epitaxy (MOVPE) grown AlN layers on sapphire substrates. Adjustment of growth kinetics is very important to control the doping. Therefore, pulsed atomic layer epitaxy (PALE) was used to control the growth kinetics and reduce parasitic reactions that inevitably caused adverse impact on the properties of the epitaxial AlN films. As a result of HRXRD (high resolution x-ray diffraction) analysis, the (002) ω FWHM decreased significantly with the PALE method, while the increase occurred due to the development of V defects for the (102) ω scan. Atomic force microscopy (AFM) analyzes showed that SiH4 led to a 3D-like growth mode. It was demonstrated that the increased SiH4 flow increased Si incorporation into the Si-doped AlN layer while increased the sheet resistance due to the self-compensating effect obtained from secondary ion mass spectroscopy (SIMS) and I–V measurement results.

In this work, MOVPE (Metalorganic Vapor Phase Epitaxy) growth and characterization studies of high Al content AlGaN epilayers are reported. We utilize high resolution X-ray diffraction (HRXRD) and atomic force microscope (AFM) techniques to analyze the crystalline quality and surface morphology of AlGaN epilayers. The role of the growth temperature of AlGaN epilayers on the structural quality and the surface morphology was investigated. Growth and measurement results show that single phase AlGaN epilayers were grown on AlN/Al2O3 template. It is concluded that the increasing growth temperature increases the Al content of AlGaN epilayers which enable to control the alloy concentration of AlGaN. Furthermore, the increasing Al content in AlGaN epilayers leads to the smooth surface which indicates that the decreasing number of dislocation density.

The aim of the present study is to test the factor structure and reliability of the Experience of Close Relationships-Relationship Structures Scale (ECR-RS) mother, father, romantic partner, close friend forms among Turkish adolescents. In order to test the structure validity of the ECR-RS, exploratory factor analysis is performed on a sample of 214 participants in Study 1, and to further investigate the structure validity, confirmatory factor analysis is performed on a second sample of 286 participants in Study 2. Within the scope of the reliability studies of the ECR-RS, internal reliability and test–retest reliability of the Turkish ECR-RS are also tested. The results of the explanatory and confirmatory factor analysis, Cronbach’s alpha coefficients, and test–retest reliability scores supported the original two-factor structure (attachment avoidance and attachment anxiety) for all forms of the ECR-RS among Turkish adolescents.

Bu calismanin amaci “Ergen Ogrencilerin Okuldaki Temel Psikolojik Ihtiyaclari Olcegi”nin Turkce faktor yapisi, gecerlik ve guvenirliginin test edilmesidir. Olcegin yapi gecerliginin sinanmasi amaciyla 266 liseli katilimciyla acimlayici faktor analizi yapilmis ve ardindan 300 liseli katilimciyla dogrulayici faktor analizi gerceklestirilmistir. Olcegin olcut gecerligi, ic tutarliligi ve madde-toplam korelasyonlarinin hesaplanmasi icin 303 liseli katilimcidan veri toplanmis ve son olarak test tekrar test guvenirliginin hesaplanmasi icin 73 liseli katilimciyla calisilmistir. Acimlayici, Dogrulayici faktor analizi, Cronbach Alfa Katsayilari, madde-toplam puanlari, olcut gecerligi ve test tekrar test sonuclari olcegin Turkce formunun Turkiye’de lise ogrencileri arasinda orjinal uc boyutlu yapiyi gosterdigini ve ergen ogrencilerin okuldaki temel psikolojik ihtiyaclarinin ne duzeyde karsilandigini olcmek uzere kullanilabilecegini gostermektedir.

Bu calisma okul sosyal ikliminin ergen ogrencilerin okulda psikolojik ihtiyaclarinin doyumundaki rolunu incelemek amaciyla yapilmistir. Calismanin katilimcilari Istanbul’da cesitli liselerinde ogrenim goren 303 lise ogrencisinden olusmaktadir. Verilerin toplanmasinda kisisel bilgi formunun yani sira, okul sosyal iklimi olcegi ve ergen ogrencilerin okuldaki temel psikolojik ihtiyaclari olcegi kullanilmistir. Verilerin analizi icin uc ayri regresyon analizi gerceklestirilmistir. Ilk regresyon analizinde yas ile okul ve akran algisinin ozerklik ihtiyacini yordamada anlamli oldugu bulunmustur. Ikinci regresyon analizinin sonuclarina gore, ogretmenler ve akranlara iliskin algi iliskisellik ihtiyacinin anlamli yordayicilari olarak bulunurken, son regresyon analizinde yetkinlik ihtiyacinin yordanmasinda yalnizca akran algisinin anlamli bir katkisi oldugu bulunmustur.

Present study aimed to examine the relative role of time spent on the internet, parents’ educational background and parental mobile phone and computer monitoring behaviors on problematic internet use among adolescents. Participants of the study were 250 high school students from İstanbul aged between 14 and 18. Problematic Internet Usage scale, Parental Monitoring Scale and Demografic Information Form were used to collect data. Results of the hierarchical regression analysis revealed that time spent on the internet, fathers’ education and parental computer monitoring together accounted for the 16% of the variance in problematic internat use among adolescents. While mothers’ educational background and parental mobile phone monitoring had no significant contribution in the model, time spent on the internet and fathers’ education were found to be stronger predictors of problematic internet use than parental computer monitoring.

WOS: 000400536000016, In this study we report the VIII ratio effects on growth, structural, optical and doping characteristics of low growth rate (similar to 1 angstrom/s) heteroepitaxial Metal Organic Chemical Vapor Deposition (MOCVD) grown In(x)A(1-x)As layers, a part of Quantum Cascade Laser (QCL) structures, on InP substrate. Especially photoluminescence (PL) properties of InAlAs-InP interface show strong dependence on AsH3 overpressure. We have shown that the VIII ratio with fixed metalorganic precursor flow is a crucial parameter on In In(x)A(1-x)As layers to have a good material quality in terms of crystallinity, optical and electrical characteristics with and without doping. (C) 2017 Elsevier Ltd. All rights reserved., Republic of Turkey, Ministry of Science, Industry and Technology-SANTEZ program [0573.STZ.2013-2]; TUBITAK PhD Program fellowship [BIDEB-2211], This study was partially supported by Republic of Turkey, Ministry of Science, Industry and Technology-SANTEZ program under grant number 0573.STZ.2013-2. Ilkay Demir acknowledges the support through TUBITAK PhD Program fellowship BIDEB-2211 Grant. The authors thank Ms. A. Alev Kizilbulut from ERMAKSAN Optoelectronics for PL measurements.

Date of Conference: 1-6 February 2020 Conference Name: SPIE OPTO, 2020: Gallium Nitride Materials and Devices XV 2020 In this work, the effect of introducing a photonic crystal network of silicon nitride (SiN) micro-domes on the backside of silver coated gallium nitride (GaN) based light emitting diodes (LEDs) was studied. First, sapphire side of the top emitting LEDs, which is the bottom surface of the LEDs, is coated with silver (Ag). Light emitted towards the sapphire substrate is reflected upwards to the top surface and the amount of light extracted from the LED is expected to increase. In an alternative approach, SiN micro-domes forming a two dimensional photonic crystal, 2 μm in diameter and 80 nm in height in average, are deposited on the light emitting surface of the device with a period of 2 μm. Coating the backside with Ag has increased the efficiency of a top emitting LED by 11%. By introducing the SiN photonic crystal onto the Ag backside coated sample, total internal reflection is reduced via scattering and the amount of light emitted has been increased by 30% at 5·104 mA/cm2. Integration of SiN micro-domes with Ag coating has significantly impacted light extraction which has been shown to increase the efficiency of GaN based LEDs. Fabrication process and the results are discussed in detail.

In the present study, the PALE-AlN (pulsed atomic layer epitaxy) epilayers were grown on the Si (111) substrates at different growth temperatures by metal organic vapor phase epitaxy (MOVPE) technique. The oxygen (O) and silicon (Si) concentrations of grown PALE-AlN epilayers and interface between epilayer and substrate were investigated by secondary ion mass spectroscopy (SIMS). It was observed that O and Si concentration change with growth temperature of epilayers as well as the interface significantly. HRXRD (high-resolution x-ray diffraction) analyses showed that the highest growth temperature results with the lowest full width at half maximum (FWHM) value for both ɷ scans. Scanning electron microscope (SEM) and atomic force microscopy (AFM) analyses indicated that relatively low growth temperature grown samples gave rise to 2D-like growth mode with openings while increased growth temperature resulted in change the growth mode to a columnar mode with increasing V-shape pits because of the increasing diffusion coefficient of O impurities and Si atoms in AlN epilayers.

WOS: 000391905300075, We report the growth of high quality InGaAs/InAlAs quantum cascade laser (QCL) structure which composed of superlattices (SLs) and the effects of interruption time between each layer of the SL structure. Inserting an interruption delay during the growth dramatically effects the quality of the SL as indicated by crystallinity, interface sharpness and optical properties. The results show that an increase in interruption time up to a certain value makes sharper interfaces and improves optical and structural properties, but, beyond that value, overall quality starts to degrade. The composition and the growth rate of each single thin layer are determined by using high resolution X-ray diffraction (HRXRD) measurements. (C) 2016 Elsevier Ltd. All rights reserved., Republic of Turkey, Ministry of Science, Industry and Technology-SANTEZ program [0573.STZ.2013-2]; TUBITAK PhD Program fellowship [BIDEB-2211, 1649B031100137]; Republic of Turkey, Ministry of Science, Industry and Technology-SANTEZ program [0573.STZ.2013-2]; TUBITAK PhD Program fellowship [BIDEB-2211, 1649B031100137], This study was partially supported by Republic of Turkey, Ministry of Science, Industry and Technology-SANTEZ program under grant number 0573.STZ.2013-2. Ilkay Demir acknowledges the support through TUBITAK PhD Program fellowship BIDEB-2211 Grant-1649B031100137. The authors thank Ms. A. Alev Kizilbulut from ERMAKSAN Optoelectronics for PL measurements.

We investigate influence of GaAs buffer layer (BL) growth parameters such as temperature and thickness on the structural, morphological, crystalline and optical quality of metal organic vapor phase epitaxy (MOVPE) grown heterostructures of GaAs on Ge. It was found that the optimal BL conditions significantly decrease the effects of anti-phase boundaries (APBs) even when grown on offcut Ge substrate by two-step growth technique with AsH3 pre-flow to promote double atomic step formation. It is observed that as the growth temperature increases, the growth rate of the GaAs BL increases, too. Improvement on the structural quality is observed up to BLs temperature of 535 °C, then it decreases. On the other hand, as the different thick BLs, 12, 25, 75 nm are considered, the epilayer grown on the 25 nm thick BL has shown the lowest full width at half maximum (FWHM) value, large photoluminescence peak intensity and internal quantum efficiency (IQE).

WOS: 000450320600014, We report on the fabrication of high brightness AlGaN-based ultraviolet light emitting diodes (UV-LED) on patterned silicon. Using the lateral epitaxial overgrowth approach, we demonstrate the growth of a 6 mu m thick AIN layer of high crystalline quality. X-ray diffraction characterization showed a rocking curve with a full width at half maximum of 553 and 768 '' for the (00.2) and (10.2) planes, respectively. The low dislocation density of the AIN template enabled the growth of bright AlGaN/GaN quantum wells emitting at 336 nm. By appropriate flip-chip bonding and silicon substrate removal processing steps, the patterned AIN surface was exposed and efficient bottom-emission UV-LEDs were realized. Improvement of the AIN quality and the structure design allowed the optical output power to reach the milliwatt range under pulsed current, exceeding the previously reported maximum efficiency. Further investigations of the optical power at different pulsed currents and duty cycles show that thermal management in this device structure is still challenging, especially in continuous wave mode operation. The strategy presented here is of interest, since AIN crystalline quality improvement and optimization of the light extraction are the main issues inhibiting efficient UV emitter on silicon fabrication.

WOS: 000463693300002, This paper presents high performance, GaN/InGaN-based light emitting diodes (LEDs) in three different device configurations, namely Top Emitting (TE) LED, conventional Flip Chip (FC) and Distributed Contact (DC) FC. Series resistances as low as 1.1 Omega have been obtained from FC device configurations with a back reflecting ohmic contact of Ni/Au/RTA/Ni/Ag metal stack. A small shift has been observed between electroluminescence (EL) emissions of TE LED and the FC LEDs. In addition, FWHM value of the EL emission of DCFC LED has shown the minimum value of 160 meV (26.9 nm). Furthermore, DCFC LED configuration has shown the highest quantum efficiency and power output, with 330 mW at 500 mA current injection, compared to that of traditional wire bonded TE LEDs and the conventional FC LEDs., Scientific and Technical Research Council of Turkey, (TUBITAK) [113G042, 115E109], We are grateful to H. Morkoc, U Ozgur, V. Avrutin of Virginia Commonwealth University for many fruitful discussions. This work is supported by Scientific and Technical Research Council of Turkey, (TUBITAK Grant no: 113G042 and 115E109).

In this work, MOVPE (Metalorganic Vapor PhaseEpitaxy) growth and characterization studies of high Al content AlGaN epilayersare reported. We utilize high resolutionX-ray diffraction (HRXRD) and atomic force microscope (AFM) techniques toanalyze the crystalline quality andsurface morphology of AlGaN epilayers. The role of the growth temperature ofAlGaN epilayers on the structural quality and the surface morphology wasinvestigated. Growth and measurement results show that single phase AlGaNepilayers were grown on AlN/Al2O3 template. It isconcluded that the increasing growth temperature increases the Al content ofAlGaN epilayers which enable to control the alloy concentration of AlGaN.Furthermore, the increasing Al content in AlGaN epilayers leads to the smoothsurface which indicates that the decreasing number of dislocation density., Bu çalışmada, yüksekAl içerikli AlGaN epi-tabakaların MOVPE (Metalorganik Buhar Fazı Epitaksi)büyütmesi ve karakterizasyon çalışmaları rapor edilmiştir. AlGaNepi-tabakaların kristal kalitesi ve yüzey morfolojisi analizi için yüksekçözünürlüklü X-ışını kırınımı (HRXRD) ve atomik kuvvet mikroskobu tekniklerikullanılmıştır. Büyütme sıcaklığının AlGaN epi-tabakalarının yapısal kalitesive yüzey morfolojisi üzerindeki rolü incelenmiştir. Büyütme ve ölçüm sonuçlarıAlN/Al2O3 şablonu üzerine tek fazda AlGaN epi-tabakalarınbüyütüldüğünü göstermektedir. Artan büyütme sıcaklığının AlGaN'in Al içeriğiniarttırdığı ve bunun AlGaN alaşım konsantrasyonunu kontrol etmeye olanaksağladığı sonucuna varılmıştır. Ayrıca, AlGaN epi-tabakalarındaki Al içeriğininartışı pürüzsüz yüzeye yol açar ki budislokasyon yoğunluğunun azaldığını belirtir.

WOS: 000418927900001, The aim of the study is to understand the effects of two stages of HT-GaN growth with different V/III ratios on optical, chemical and structural characteristics of the HT-GaN layer. In addition, the effects of two-stage growth on the transport properties has been presented through fabricated Schottky diodes. As the V/III ratio in the 1st stage growth of HT-GaN layer is varied, it has been observed that recovery of reflectance is faster with higher V/III ratios, while no significant effect has been observed by changing the V/III ratios in the 2nd stage of HT-GaN growth. The 2nd stage growth is caused to decrease in screw dislocation densities obtained from the high-resolution x-ray diffraction measurements. The lowest edge type dislocation densities have been obtained for samples with lower V/III ratios in both the 1st and 2nd stages of HT-GaN growth. Well-defined terraces and a few GaN atomic layer surface roughness have been realized through the atomic force microscopy measurements on all the samples. Ga atom bound oxygen states has been investigated through the x-ray photoelectron spectroscopy to find out the V/III ratio effect on the impurity incorporation. An increase in the V/III ratio has given rise to a higher percentage of oxygen incorporation during the 2nd stage of growth. The lowest internal quantum efficiency has been obtained for the samples grown at the highest V/III ratio for both the 1st and 2nd growth stages. Fine excitonic transitions have been indicated by the low temperature high-resolution photoluminescence measurements. Current-voltage measurements performed on the Schottky diodes have shown the effects on the diode parameters., TUBITAK [113G103, 115E109], The authors acknowledge the usage of Nanophotonics Research and Application Center at Cumhuriyet University (CUNAM) facilities. This work is supported by TUBITAK under Project Nos 113G103 and 115E109. The authors acknowledge the contributions of Mr Baris Bulut from Ermaksan Optoelectronic during growth studies.

WOS: 000459827000007, We report the effect of total carrier gas flow of GaN during both GaN nucleation layer and high temperature GaN growth steps on structural, optical, electrical and morphological properties. The formation of dislocations in GaN layer and their effects were investigated in detail as a function of carrier gas flow. It has been found that the more carrier gas requires longer recovery time for transition from 3D (3 dimensional) to 2D growth and results in smaller edge-type dislocation density. The images obtained from the AFM measurements have shown terraces widths varying between 60-150 nm depending on the hydrogen flow rate., TUBITAK [113G103, 115E109]; Cumhuriyet University [M-699], The authors acknowledge the usage of Nanophotonics Research and Application Center at Cumhuriyet University (CUNAM) facilities. This work is supported by the TUBITAK under project nos. 113G103 and 115E109 and by Scientific Research Project Fund of Cumhuriyet University under the project number M-699. The authors thank Ms. A. Alev Kizilbulut from ERMAKSAN Optoelectronics for room temperature PL measurements.

InxGa1-xAs layers on undoped InP (100) substrateswere grown with Aixtron 200-4RF/S horizontal Metal Organic Chemical Vapour Deposition (MOCVD)reactor. All the epilayers havebeen grown with different indium compositions. Thickness of the samples were measured via ScanningElectron Microscopy (SEM). Indium concentrations were defined by HighResolution X-ray Diffraction (HRXRD) and optical measurements were done withspectroscopic ellipsometry in order to obtain refractive index (n) andthickness of the samples. In-situ reflectance is used to measure thickness ofsamples. Then all of the thicknesses are compared., InxGa1-xAs tabakaları katkısız InP (100) alttaşüzerine Aixtron 200-4 RF/S yatayMetal Organik Kimyasal Buhar Depolama (MOCVD) sistemi ile büyütülmüştür. Bütün epikatmanlar farklı indiyumkonsantrasyonlarında büyütülmüştür. Katmanların kalınlıkları Taramalı ElektronMikroskobu (SEM) ile ölçülmüştür. İndiyum konsantrasyonları Yüksek ÇözünürlüklüX-ışını Kırınım (HRXRD) cihazı ile tayin edildi ve kırılma indisi (n) vekalınlıkların belirlenmesi için optiksel ölçümler spektroskopik elipsometre ileyapıldı. In-situ yansıma, örneklerin kalınlıklarının belirlenmesi içinkullanılmıştır. Son olarak bütün kalınlıklar karşılaştırılmıştır.

WOS: 000326552300011, We have calculated the binding energy for the ground state of a heavy-hole exciton in GaAs/Ga0.7Al0.3As cylindrical quantum well wires (CQWWs) under the action of a hydrostatic pressure, temperature and magnetic field. The calculations are made using variational methods and the effective mass approximation for a finite confinement potential. The hydrostatic pressure, temperature and magnetic field effects can be summarized as follows; excitonic binding energy is a decreasing function of temperature for fixed pressure and magnetic field also is an increasing function of pressure for fixed temperature and magnetic field values depending on the applied pressure range. For larger magnetic field strengths, the binding energies get larger for any hydrostatic pressure and temperature values as expected. (C) 2013 Elsevier Ltd. All rights reserved.