Examination of the temperature related structural defects of InGaN/GaN solar cells

In this study the effects of the annealing temperature on the InGaN/GaN solar cells with different In-contents grown on sapphire substrate by the Metal Organic Chemical Vapor Deposition (MOCVD) are analyzed by High Resolution X-ray Diffraction (HRXRD) and an Atomic Force Microscope (AFM). The plane angles, mosaic crystal sizes, mixed stress, dislocation intensities of the structure of the GaN and InGaN layers are determined. According to the test results, there are no general characteristic trends observed due to temperature at both structures. There are fluctuating failures determined at both structures as of 350 °C. The defect density increased on the GaN layer starting from 350 °C and reaching above 400 °C. A similar trend is observed on the InGaN layer, too. © 2015 Elsevier Ltd. All rights reserved

Growth and investigation of bio-sensor properties of Al:ZnO thin films

Bu çalışmada, Saçtırma tekniği ile Si, cam ve kuartz alttaş üzerine büyütülen AZO (Al katkılı çinko oksit) ince filmlerin yapısal ve optik özellikleri araştırıldı. Si alttaş üzerine büyütülen AZO ince filmlerin yapısı, lüminesas özellikleri, yüzey morfolojisi ayrıntılı bir şekilde incelendi. Biriktirilen AZO filmlerinin direnç değerlerinin oldukça yüksek olması sebebiyle sensör uygulamalarında kullanılamadı. Biyosensör uygulamalarında kullanılmak üzere cam alttaş üzerine AZO ince filmler büyütüldü. Farklı Rf güçlerinde büyütülen AZO filmlerinin yapısal ve optiksel analizi gerçekleştirildi. Hazırlanan biyosensörün temelinde reaksiyon ürünü olarak hidrojen peroksit açığa çıktığı için, hidrojen peroksite (H2O2) karşı duyarlılık belirlendi. Cam üzerine biriktirilen yapının yüksek sıcaklık dayanımı iyi olmadığından ve altının daha iyi kaplanması amacıyla alttaş olarak kuartz kullanılarak ZnO/Au yapısı yeniden oluşturuldu. Ayrıca kaplamadaki kopmaları önlemek için Au ara-tabakasının kaplama sıcaklığı 200°C?den 500°C?ye yükseltildi. Hidrojen peroksite, glukoza ve kolesterole karşı duyarlılığı belirlendi. Oluşturulan filmin yapısal ve optik özellikleri XRD, PL ve AFM ile analiz edildi. Hazırlanan bu elektrotun H2O2? ye duyarlı olduğu bulundu. Glukoz ve Kolesterole karşı ayrı ayrı duyarlılık deneyleri yapıldı. Artan glukoz ve kolesterol derişimlerine karşı akımlarda da paralel olarak bir artış gözlendi. Glukoz ve Kolesterol çözeltilerinin ilavesiyle akımların artması glukozun ve kolesterolün enzimatik reaksiyon sonucu ürünlerinin elektrokimyasal olarak belirlenebileceği bulundu.In this study, Structural and optical properties of AZO (Al doped ZnO) thin films grown on Si, glass and quartz substrates by Rf magnetron sputtering were investigated. XRD, PL and AFM techniques were used for characterization of the samples. Structure, luminescence properties and surface morphology of AZO films deposited on Si substrate were examined in detail. AZO/Si thin films could not be used for sensor applications due to the relatively high values of resistance. AZO/Au thin films were deposited on the glass substrate to use in biosensor application. Structural and optical analysis of AZO/Au films deposited in different Rf powers were carried out. Hydrogen peroxide is the reaction product of biosensors. Therefore, the sensitivity to hydrogen peroxide (H2O2) was determined. High temperature resistance of the structure grown on glass was not so good. Then in order to better coating of gold, the quartz substrate using was used to deposite and to increase the growth quality of gold coating. ZnO\Au film was be rebuilt. In addition, mid-layer of Au coating temperature was increased from 200ºC to 500ºC for breakage of the coating and AZO layer thickness was increased to 100 nm. Sensitivity to hydrogen peroxide, glucose and cholesterol were determined. The structural and optical properties of the film was analyzed by XRD, PL and AFM. This ZnO/Au electrode was found to be sensitive to H2O2. Increased glucose and cholesterol concentrations increased in parallel to the observed currents. As a result of enzymatic reaction of glucose and cholesterol, the products can be found in the electrochemical

Analysis of the Mosaic Defects in Graded and Non Graded In_xGa_1-xN Solar Cell Structures

In this study, graded (A) InxGa1-xN (10.5 ≤ x ≤ 18.4) and non graded (B) InxGa1-xN (13.6 ≤ x ≤ 24.9) samples are grown on c-oriented sapphire substrate using the Metal Organic Chemical Vapour Deposition (MOCVD) technique. The structural, optical and electrical features of the grown InGaN/GaN solar cell structures are analyzed using High Resolution X-Ray Diffraction (HRXRD), Photoluminescense (PL), Ultraviolet (UV), current density and potential (JV) measurements. According to the HRXRD results; it is determined that the InGaN layer of the graded structure has a lower FWHM (Full width at half maximum) value. From the PL measurements, it is observed that the GaN half-width peak value of the graded sample is narrower and the InGaN peak width value of the graded sample is larger. From UV measurements, that the graded sample has a greater band range. JV measurements determine that the performance of the graded structure is higher

The study on characterizations of SrTiO3 thin films with different growth temperatures

Strontium titanate (SrTiO3) thin films were deposited on cleaned p-type (100) oriented silicon substrates using radio frequency (RF) magnetron sputtering method at a substrate temperatures of 200 degrees C, 300 degrees C, 400 degrees C and 500 degrees C. During deposition, sputtering pressure (P-S) was maintained at 3.9 x 10(-3) Torr using argon (A(r)) gas, and RF power (P-RF) was set to a constant value of 100W for all experiments. Crystalline quality, surface morphology and band gap of the films were investigated by X-ray diffraction (XRD) analysis, atomic force microscopy (AFM) and photoluminescence (PL) measurements. Experimental results showed crystalline quality, and surface morphology of the films were remarkably improved by high substrate temperature. In addition to above analyzes, SrTiO3/p-Si structure deposited at 500 degrees C substrate temperature have been investigated using temperature dependent currentvoltage (I-V-T) characteristics in the temperature range of 110-350 K by steps of 30 K due to its better characteristics. The ideality factor (n), barrier height (Phi(b)) and series resistance (R-s) values were extracted. Moreover, Phi(b) and R-s values were recalculated using Norde's method. (C) 2014 Elsevier Ltd. All rights reserved

DFT Studies on Electronic, Elastic, Thermoelectric and Optical Properties of New Half-Heusler XRhZ (X = V, Nb and Z = Si, Ge) Semiconductors

Density functional theory is used to explore the physical properties of the new half-Heusler alloys XRhZ (X =V, Nb and Z = Si, Ge). The exchange-correlation effects were treated by the TB-mBJ potential. The four studied compounds are nonmagnetic semiconductor with an indirect band gap. The formation enthalpy, cohesive energy and phonon band structures demonstrated that these semiconductors are structurally and dynamically stable. It was predicted by the elastic study that the XRhZ compounds (X = V, Nb and Z = Si, Ge) have stable mechanical properties, they possess an anisotropic character and reveal the ductile nature with a B/G ratio >1.75. The optical results show an interesting photocatalytic potential for the NbRhSi and NbRhGe semiconductors; they exhibit a high absorption coefficient in the visible domain, which is around 112.104 cm-1. For energies greater than 10 eV (UV domain), the refractive index is less than one. The thermoelectric results confirmed that the XRhZ (X=V, Nb and Z=Si, Ge) compounds are very attractive for thermoelectric devices working in large temperature range including ambient temperature

Microstructural Analysis with Graded and Non-Graded Indium in InGaN Solar Cell

In this study are graded and non graded InGaN/GaN samples grown on c-oriented sapphire substrate using the Metal Organic Chemical Vapour Deposition (MOCVD) technique. The structural and morphological properties of the grown InGaN/GaN solar cell structures are analyzed using High Resolution X-ray Diffraction (HRXRD), atomic force microscopy (AFM). Each structures c and a lattice parameters strain, biaxial strain, hydrostatic strain, stress, lattice relax, tilt angle, mosaic crystal size, dislocation densities of GaN and InGaN layers are determined by XRD measurements. In accordance with these calculations, the effect of graded structure on the defects, are discussed. As a dramatic result; although values of full width at half maximum (FWHM) are broad, a considerable decrease at dislocations is noticed. The AFM observations have revealed that the two dimensional growth of the graded sample is more significant and its roughness value is lower. JV measurements shown that the performance of the graded structure is higher. It is determined that all test results are consistent with each other

Preparation of RF sputtered AZO/Au thin film hydrogen peroxide sensitive electrode for utilization as a biosensor

In this study, hydrogen peroxide (H2O2) sensitive Al doped ZO(AZO)/Au thin film electrode has been developed for the utilization as a biosensor. A preferred c-axis oriented AZO/Au thin film was deposited on quartz substrate by RF magnetron sputtering at room temperature. Structural, morphological and optical properties of the AZO film were analyzed by X-ray diffraction, atomic force microscopy and photoluminescence. The sensor performance was characterized by electrochemical analysis device. The sensibility of prepared thin film electrodes to H2O2 was studied. The dependence of amperometric response current on the glucose and cholesterol concentrations was also investigated.WOS:0003371679000482-s2.0-8490254806

Examination of the temperature related structural defects of InGaN/GaN solar cells

In this study the effects of the annealing temperature on the InGaN/GaN solar cells with different In-contents grown on sapphire substrate by the Metal Organic Chemical Vapor Deposition (MOCVD) are analyzed by High Resolution X-ray Diffraction (HRXRD) and an Atomic Force Microscope (AFM). The plane angles, mosaic crystal sizes, mixed stress, dislocation intensities of the structure of the GaN and InGaN layers are determined. According to the test results, there are no general characteristic trends observed due to temperature at both structures. There are fluctuating failures determined at both structures as of 350 degrees C. The defect density increased on the GaN layer starting from 350 degrees C and reaching above 400 degrees C. A similar trend is observed on the InGaN layer, too. (C) 2015 Elsevier Ltd. All rights reserved.DPTHAMITTurkiye Cumhuriyeti Kalkinma Bakanligi; DPT-FOTONTurkiye Cumhuriyeti Kalkinma Bakanligi; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [113E331, 109A015, 109E301]; [NATO-SET-193]This work is supported by the projects DPTHAMIT, DPT-FOTON, NATO-SET-193 and TUBITAK under Project Nos. 113E331, 109A015 and 109E301.WOS:0003626031000452-s2.0-8493884290

Microstructural Analysis with Graded and Non-Graded Indium in InGaN Solar Cell

In this study are graded and non graded InGaN/GaN samples grown on c-oriented sapphire substrate using the Metal Organic Chemical Vapour Deposition (MOCVD) technique. The structural and morphological properties of the grown InGaN/GaN solar cell structures are analyzed using High Resolution X-ray Diffraction (HRXRD), atomic force microscopy (AFM). Each structures c and a lattice parameters strain, biaxial strain, hydrostatic strain, stress, lattice relax, tilt angle, mosaic crystal size, dislocation densities of GaN and InGaN layers are determined by XRD measurements. In accordance with these calculations, the effect of graded structure on the defects, are discussed. As a dramatic result; although values of full width at half maximum (FWHM) are broad, a considerable decrease at dislocations is noticed. The AFM observations have revealed that the two dimensional growth of the graded sample is more significant and its roughness value is lower. JV measurements shown that the performance of the graded structure is higher. It is determined that all test results are consistent with each other

Preparation of RF sputtered AZO/Au thin film hydrogen peroxide sensitive electrode for utilization as a biosensor

In this study, hydrogen peroxide (H2O2) sensitive Al doped ZO(AZO)/Au thin film electrode has been developed for the utilization as a biosensor. A preferred c-axis oriented AZO/Au thin film was deposited on quartz substrate by RF magnetron sputtering at room temperature. Structural, morphological and optical properties of the AZO film were analyzed by X-ray diffraction, atomic force microscopy and photoluminescence. The sensor performance was characterized by electrochemical analysis device. The sensibility of prepared thin film electrodes to H2O2 was studied. The dependence of amperometric response current on the glucose and cholesterol concentrations was also investigated