scholarly journals Photovoltaic Response of Silicon Wafers Treated in the K2WO4-Na2WO4-WO3 Melt

2021 ◽  
Author(s):  
Alexander Valer'evich Kosov ◽  
Olga Leonidovna Semerikova ◽  
Sergey Vakarin ◽  
Olga Vladimirovna Grishenkova ◽  
Alexey Alexeevich Trofimov ◽  
...  
Keyword(s):  
Photocurrent Density ◽  
Silicon Wafers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Contact Points ◽  
Atomic Force ◽  
Naoh Solution ◽  
Scanning Electron ◽  
Si Wafer

Abstract Texturing silicon wafers is one way to increase the performance of solar cells. This work is the first to report on the surface modification of Si wafers by processing in polytungstate melts. Scanning electron microscopy, atomic force microscopy, X-ray diffraction analysis, the Brunauer–Emmett–Teller method, and photoelectrochemical measurements were used to elucidate the effect of texturing conditions in the Na2WO4 – K2WO4 (1:1) melt containing 35 or 50 mol% WO3 at 973 K in air. As a result of cathodic treatment in the melt containing 50 mol% WO3 at the potential of –0.92 V (vs. Pt) for 15 s, upright pyramids were formed on the Si surface. In addition, inverted pyramids appeared at the OTB/Si contact points. The photocurrent density of these samples was several times higher than that for the initial Si wafer or the Si wafer etched in 5M NaOH solution at 353 K for 20 min. Mechanisms for the formation of upright and inverted pyramids were proposed. Unusual eight-faceted pyramids were formed on the Si surface during cathodic treatment in the melt containing 35 mol% WO3 at –1.19 V for 15 s, but the photocurrent density of such samples was low.

Lateral Size of Self-Patterned Nanostructures Controlled by Multi-Step Deposition

2005 ◽  
Vol 106 ◽  
pp. 117-122 ◽  
Author(s):  
Izabela Szafraniak ◽  
Dietrich Hesse ◽  
Marin Alexe
Keyword(s):  
Electron Microscopy ◽  
Ultrathin Films ◽  
Lateral Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Non Volatile Memory ◽  
Ferroelectric Capacitors ◽  
Scanning Electron

Self-patterning presents an appealing alternative to lithography for the production of arrays of nanoscale ferroelectric capacitors for use in high density non-volatile memory devices. Recently a self-patterning method, based on the use of the instability of ultrathin films during hightemperature treatments, was used to fabricate nanosized ferroelectrics. This paper reports the use of the method for the preparation of PZT nanoislands on different single crystalline substrates - SrTiO3, MgO and LaAlO3. Moreover, a multi-step deposition procedure in order to control lateral the dimension of the crystals was introduced. The nanostructures obtained were studied by atomic force microscopy, scanning electron microscopy and X-ray diffraction.

Wettability and Nanotribological Response of Silicon Surfaces Functionalized by Ion Implantation

2012 ◽  
Vol 730-732 ◽  
pp. 257-262
Author(s):  
Bruno Nunes ◽  
Sergio Magalhães ◽  
Nuno Franco ◽  
Eduardo Alves ◽  
Ana Paula Serro ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ion Implantation ◽  
Silicon Surfaces ◽  
Iron Ions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Scanning Electron

Aiming to improve the nanotribological response of Si-based materials we implanted silicon wafers with different fluences of iron ions (up to 2x1017 cm-2). Implantation was followed by annealing treatments at temperatures from 550°C to 1000°C. The implanted surfaces were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and wettability tests. Then, samples were submitted to AFM-based nanowear tests. We observe an increase of both hidrophobicity and and wear resistance of the implanted silicon, indicating that ion implantation of Si can be a route to be deeper explored in what concerns tribomechanical improvement of Si.

Grain Size Effect on Lattice of Ni Nanocrystals Prepared Through Polyol Method

2008 ◽  
Vol 8 (8) ◽  
pp. 4127-4131 ◽  
Author(s):  
G. S. Okram ◽  
Kh. Namrata Devi ◽  
H. Sanatombi ◽  
Ajay Soni ◽  
V. Ganesan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Grain Size ◽  
Polyol Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Scanning Electron

Nanocrystalline nickel powders were prepared with grain size 'd' in the range 40–100 nm diameters through polyol method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used for characterization. XRD of the prepared samples consistently matched with standard fcc structure of nickel without any impurity peak. Detailed analysis and calculations using Scherrer equation for (111) peak revealed systematic increase in line width and peak shifting towards lower diffraction 2θ angles with decrease in nickel to ethylene glycol mole ratio. Different values of d estimated from various peaks of each sample suggested associated microstrains in the nanograins. Values of d estimated from X-ray diffraction patterns were compared with those obtained from atomic force microscopy and scanning electron microscopy results, and discussed. Observed lattice expansion is explained, on the basis of a theoretical model of linear elasticity.

scholarly journals The Influence of the Preparation and Stability of Nanofluids for Heat Transfer

2019 ◽  
Vol 25 (4) ◽  
pp. 45-54 ◽  
Author(s):  
Noor Sabih Majeed ◽  
Basma A. Abdulmajeed ◽  
Anwar Khudhur Yaseen
Keyword(s):  
Heat Transfer ◽  
Electron Microscopy ◽  
Base Fluid ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Stability ◽  
Scanning Electron

Recently the use of nanofluids represents very important materials. They are used in different branches like medicine, engineering, power, heat transfer, etc. The stability of nanofluids is an important factor to improve the performance of nanofluids with good results. In this research two types of nanoparticles, TiO2 (titanium oxide) and γ-Al2O3 (gamma aluminum oxide) were used with base fluid water. Two-step method were used to prepare the nanofluids. One concentration 0.003 vol. %, the nanoparticles were examined. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffraction (XRD) were used to accomplish these tests. The stability of the two types of nanofluids is measured by zeta potential and UV-vis spectrophotometer. The results showed that γ-Al2O3/water has more stable than TiO2/ water for the same period of time.  

Fabrication and Characterization of Polyaniline–ZnO Hybrid Nanocomposite Thin Films

2008 ◽  
Vol 8 (4) ◽  
pp. 1757-1761 ◽  
Author(s):  
Ajeet Kaushik ◽  
Jitendra Kumar ◽  
M. K. Tiwari ◽  
R. Khan ◽  
B. D. Malhotra ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Nanocomposite Thin Films ◽  
Scanning Electron

Polyaniline (PANI)–ZnO nanocomposite thin film has been successfully fabricated on glass substrates by using vacuum deposition technique. The as-grown PANI–ZnO nanocomposite thin films have been characterized using X-ray diffraction, Scanning Electron Microscopy, Atomic Force Microscopy, UV-visible spectrophotometer and Fourier Transform Infrared (FTIR) spectroscopy, respectively. X-ray diffraction of as-grown film shows the reflection of ZnO nanoparticles along with a broad peak of PANI. The surface morphology of nanocomposite films has been investigated using scanning electron microscopy and atomic force microscopy. The hypsochromic shift of the UV absorption band corresponding to π–π* transition in polymeric chain of PANI and a band at 504 cm –1 due to ZnO nanoparticles has been observed in the FTIR spectra. The hydrogen bonding between the imine group of PANI and ZnO nanoparticle has been confirmed from the presence of the absorbance band at 1151 cm–1 in the FTIR spectra of the nanocomposite thin films.

Structural and Surface Studies of Undoped Porous GaN Grown on Sapphire

2012 ◽  
Vol 620 ◽  
pp. 45-49
Author(s):  
Mahmood Ainorkhilah ◽  
Hassan Zainuriah ◽  
Yusof Yushamdan ◽  
Fong Kwong Yam ◽  
Lee Siang Chuah ◽  
...  
Keyword(s):  
Electrochemical Etching ◽  
Optoelectronic Devices ◽  
Pore Morphology ◽  
X Ray Diffraction ◽  
Porous Sample ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sem Micrograph ◽  
Scanning Electron

Owing to its great potential in optoelectronic devices, structural and surface properties of porous GaN prepared by UV electrochemical etching has been investigated. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and high resolution X-ray diffraction (HR-XRD) phi-scan and rocking curves measurements revealed the nature of the pore morphology and nanostructures. SEM micrograph indicated that the shapes of pores for porous sample are nearly hexagonal. The AFM measurements revealed that the surface roughness increased in the porous sample. X-ray diffraction phi-scan showed that porous GaN sample maintained the epitaxial feature.

Preparation of Photocatalytic Nanostructured TiO2 Thin Films

2008 ◽  
Vol 587-588 ◽  
pp. 795-799 ◽  
Author(s):  
A. Di Paola ◽  
M. Addamo ◽  
M. Bellardita ◽  
E. García-López ◽  
G. Marcì ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dip Coating ◽  
Coating Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Glass Slides ◽  
Scanning Electron

Photoactive films consisting of pure anatase, brookite or rutile were deposited on glass slides by a dip coating process from water dispersions or solutions obtained by using TiCl4 as the precursor. The films were characterized by X-ray diffraction, scanning electron microscopy and atomic force microscopy. The photocatalytic activity of the various samples was evaluated by using the photooxidation of 2-propanol in gas solid regime as probe reaction. Brookite and anatase films showed a good photoactivity degrading the substrate and the propanone produced during the reaction.

scholarly journals SUPERFÍCIES DE TITÂNIO MODIFICADAS POR OXIDAÇÃO À PLASMA EM CÁTODO OCO

2015 ◽  
Author(s):  
Marco Aurélio Medeiros da Silva ◽  
Paulo Victor de Azevedo Guerra ◽  
Ricardo Alexsandro de Medeiros Valentim ◽  
Hélio Roberto Hékis ◽  
Karilany Dantas Coutinho ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Atomic Force Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Scanning Electron

Uma nova metodologia de oxidação de superfícies de implantes de titânio foi desenvolvida com o intuito de remover previamente os óxidos primários formados espontaneamente durante a usinagem de peças de titânio. Com o objetivo de solucionar esse problema, utilizou-se neste trabalho o plasma como fonte energética tanto na remoção desses óxidos, como na oxidação de superfície de titânio. Nesse sentido, discos de Titânio tiveram seus óxidos previamente removidos por plasma com atmosfera de 50% Ar + 50% H2 seguidos da oxidação pela técnica de descarga por cátodo oco.  A oxidação foi realizada numa mistura de argônio (60%) e oxigênio (40%) até atingir a pressão de 220 Pa durante 60 min a 500°C. Em seguida caracterizou-se as superfícies oxidadas e controle por difração de Rx (X-Ray diffraction), microscopia de força atômica AFM (Atômic Force Microscopy) e microscopia eletrônica de varredura (SEM) (Scanning Electron Microscopy). Resultados obtidos por X-Ray rasante indicou que o processo de remoção dos óxidos foi eficaz, reduzindo TiO2 para Tia.  Com relação ao processo de oxidação, verificou-se que houve um aumento de 61% para 76% na concentração de O2 e a amostra oxidada apresentou-se rica em óxidos como TiO2. Na caracterização por AFM as amostras oxidadas apresentaram defeitos nas superfícies com geometria variada para picos e vales. As diferenças topográficas entre a superfície oxidada e controle são discutidas em termos das dimensões médias dos poros e dos parâmetros de rugosidade Ra, Rp e Rz. Ensaios biológicos foram também realizados com o intuito de observar a adesão e proliferação celular. No SEM observou-se espraiamento celular, uma maior quantidade de projeções de filopódios e diferenças morfológicas nas células das amostras oxidadas em comparação com a amostra controle. Na proliferação celular as células mostraram uma preferência por superfícies oxidadas onde o número de células aderidas foi comparativamente superior, em relação à amostra controle. Concluímos que o processo foi eficiente na remoção dos óxidos primários bem como na oxidação da superfície do titânio.

Structural and Optical Properties of Cu2MnSnS4 Thin Film Fabricated by Sol-Gel Technique

2015 ◽  
Vol 814 ◽  
pp. 39-43 ◽  
Author(s):  
Lei Lei Chen ◽  
Hong Mei Deng ◽  
Ke Zhi Zhang ◽  
Ling Huang ◽  
Jian Liu ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gel Technique ◽  
Scanning Electron

Cu2MnSnS4 thin film was successfully prepared by a sol-gel technique on soda lime glass substrate from metal salts and thiourea. The structural and morphological properties of the fabricated film were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and atomic force microscopy. The combination of the X-ray diffraction results and Raman spectroscopy reveal that this obtained layer is composed by Cu2MnSnS4 phase and has a stannite structure with preferential orientation along the (112) direction. The scanning electron microscopy and atomic force microscopy results show that the synthesized thin film is smooth and compact without any visible cracks or pores. The band gap of the Cu2MnSnS4 thin film is about 1.29 eV determined by the UV-vis-NIR absorption spectra measurement, which indicates it has potential applications in solar cells.

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