ICMCTF2016 Session FP: Symposium F Poster Session

Thursday, April 28, 2016 5:00 PM in Room Grand Hall

Thursday Afternoon

Time Period ThP Sessions | Topic F Sessions | Time Periods | Topics | ICMCTF2016 Schedule

FP-1 Preparation of Cu2O Films by Fe-assisted Chemical Bath Deposition Technique
Tomoaki Terasako (Graduate School of Science and Engineering, Ehime University, Japan); Yuya Ohmori, Takuya Saeki, Naoki Monden (Faculty of Engineering, Ehime University, Japan); Masakazu Yagi (National Instiutute of Technology, Kagawa College, Japan)

Cupric oxide (CuO) with a monoclinic struture and cuprous oxide (Cu2O) with a cubric structure, stable phases of the well-established copper-oxide compounds, exhibit naturally p-type conduction derived from copper vacancies (VCu). The band gap energies of CuO and Cu2O have been reported to be ~1.35 and ~2.1eV, respectively [1]. On the other hand, zinc oxide (ZnO) with a hexagonal wurtzite structure has the band gap energy of 3.37 eV, which is transparent to the visible light. It is also known that ZnO films doped with the group III elements (B, Al, Ga and In) or the VII element (F) exhibit low resistivity n-type conduction. Therefore, much attention has been paid to the fabrication of ZnO/Cu2O or ZnO/CuO heterojunction solar cells. Recently we have reported the successful growth of the cone-shape ZnO nanorods (NRs)/CuO/ heterojunctions by chemical bath depostion (CBD) [2,3]. In this paper, we will describe a new and simple CBD based technique to prepare Cu2O films.

The mixed aqueous solution of Cu(NO3)23H2O and hexamethylenetetramine (HMT) poured into a Pyrex glass beaker was placed into the water bath and stirred by the rotator. The Au/SiO2/Si wafer with a piece of iron (Fe) plate on its rear was immersed in the mixed aqueous solution. The concentration of the mixed aqueous solution was varied in the range from 0.012 to 0.075 M. The molar ratio of HMT to Cu(NO3)23H2O in the mixed solutions was kept at 1:1. The growth time was chnaged in the range from 5 to 180 min. The bath temperature was maintained at 88 °C.

No film was formed on the Au/SiO2/Si substrate wihout the assistance of the Fe plate. The use of the Fe plate led to the formation of the reddish brown films. The films exhibited (110), (111), (200),(220) and (311) peaks of cubic Cu2O except for the (400) peak of Si and the (111) peak of Au. Regardless of the growth time, the films grown from the aqueous solution of 0.05 M were composed of angular-shaped grains. With the growth time, however, both the average grain size and the film thickness increased continuously. When the growth time increased from 15 to 180 min, the growth rate decreased from 70 to 34 nm/min. The surface morphology was found to be strongly dependent on the concentration of the mixed aqueous solution. Especially, the film grown using the mixed aqueous solution of 0.012 M was composed of rounded particles and nanowires.

<<References>> [1]B. K. Meyer et al., Phys. Status Solidi B 249 (2012) 1487. [2] T. Terasako et al. , Sol. Energ. Mater. Sol. Cells 132 (2015) 74. [3] T. Terasako et al. Thin Solid Films (to be published).

FP-2 Influence of Power and Temperature on Properties of Sputtered AZO Films
Kartik Patel, Sushant Rawal (Chandubhai S. Patel Institute of Technology (CSPIT), Charotar University of Science and Technology (CHARUSAT), India)

Aluminum-doped zinc oxide films (AZO) were deposited on glass substrates by magnetron sputtering. The effect of power and deposition temperature on wettability and optical properties of AZO films are studied in detail. The increase of RF power from 60W to 180W leads to evolution of (100), (002) and (101) textures of zinc oxide. The XRD results shows increased preferred orientation of (002) plane along c-axis for deposited AZO films and its grain size increases with increase in deposition temperature from 200ºC to 600ºC. The static and dynamic contact angle formed by water and ethylene glycol varies as a function of RF power and deposition temperature. The optical properties like transmission, refractive index and band gap were measured in the wavelength range of 350-800 nm.

FP-5 Influence of dcMS and HPPMS in a dcMS/HPPMS Hybrid Process on Plasma and Coating Properties
Kirsten Bobzin, Tobias Brögelmann, Nathan Kruppe, Martin Engels, Stephan Chromy (RWTH Aachen University, Germany)
Within the physical vapor deposition (PVD) high power pulse magnetron sputtering (HPPMS) or high power impulse magnetron sputtering (HiPIMS) is a frequently studied technology in the last years. HPPMS offers the possibility to produce coatings with lower roughness, denser microstructure and better mechanical properties in comparison to direct current magnetron sputtering (dcMS). However, HPPMS is known to have much lower coating growth rate due to the low duty cycle compared to dcMS. From an economic point of view, this is an important disadvantage of the HPPMS technology. An approach to overcome this issue is the dcMS/HPPMS hybrid technology, whereby dcMS and HPPMS cathodes are used simultaneously to combine the two technologies’ benefits. In hybrid processes, the influence dcMS and HPPMS on the plasma and coating properties is of crucial interest. Therefore, in the present work measurements on plasma properties as well as on coating properties using dcMS, HPPMS and dcMS/HPPMS hybrid (Cr,Al)N processes were carried out using two Cr targets with 20 plugs of Al. One target was mounted on a HPPMS cathode and the other on a dcMS cathode within an industrial scale PVD coating unit. For the dcMS (Cr,Al)N process, only the dcMS cathode was powered with PdcMS = 3 kW, for the HPPMS (Cr,Al)N process only the HPPMS cathode was powered with PHPPMS = 5 kW. Furthermore, the HPPMS pulse duration and pulse frequency were varied. Both cathodes were powered for the dcMS/HPPMS hybrid process using the same varying parameters. In a first step, the plasma was analyzed using dcMS, HPPMS and dcMS/HPPMS hybrid processes. Changes in the plasma composition were investigated by optical emission spectroscopy (OES). The ion energy distribution function (IEDF) and the ion current density were investigated by retarding field energy analyzer (RFEA). In a second step, (Cr,Al)N coatings were produced using the same process parameters. The coatings were analyzed regarding the microstructure by scanning electron microscopy (SEM) as well as the universal hardness and the indentation modulus by nanoindentation. Furthermore, the chemical composition of the coatings was analyzed by energy dispersive X-ray spectroscopy (EDX). By comparing the measurement data the influence of dcMS and HPPMS in the dcMS/HPPMS hybrid process on the plasma were revealed and correlated with the coating properties.
FP-7 The Effect of TiO2 Coating on NiTi Alloys After MAO Treatment for Corrosion Resistance
Kubra Akar, Yasar Totik, Ihsan Efeoglu (Ataturk University, Turkey); EbruEmine Sukuroglu (Gumushane University, Turkey); Ersin Arslan (Ataturk University, Turkey); Suleyman Sukuroglu (Gumushane University, Turkey)

NiTi alloys exhibit good properties like shape memory behavior, high corrosion resistant, having the closest elasticity modulus of a human bone, superior biocompatibility properties e.i. However, the surface problems that arise during the use of this alloy limits the usage in the industry and health sector. in recent years, micro-arc oxidation (MAO) method is used to improve the surface properties and increase the usage of these alloys. In this study, the TiO2 coatings were deposited on yhe NiTİ substrates. The surface topography, morphology, crystallographic structure and thickness of the coatings were determined using Scanning Electron Microscopy (SEM), XRD. The hardness was measured using a microhardness tester. Corrosion properties were investigated by using potentiostat test unit in two different media as NaCl solution and simulated body fluid (SBF). The results show that the coated samples have higher corrosion resistance than uncoated samples in the two different media.

Key Words: MAO, Corrosion resistant, NiTi alloy

FP-8 Effect Of Doping In Bismuth Oxide Thin Films For Photocatalytic Applications
Juan Medina, Monserrat Bizarro, Agileo Hernández‑Gordillo, Sandra Rodil (Universidad Nacional Autónoma de México - Instituto de Investigaciones en Materiales, Mexico)

Bismuth oxide (Bi2O3), nitrogen doped bismuth oxide (Bi2O3:N) and tantalum doped bismuth oxide (Bi2O3:Ta) thin films were deposited by magnetron sputtering technique. The results indicated that it was possible to obtain Bi2O3 films in pure cubic delta phase, even though we have introduced other elements in the original crystalline structure. X-ray diffraction, profilometry, scanning electron microscopy, and optical transmission were used to characterize the films. The photocatalytic activity for each one of the Bi2O3 films was evaluated testing the degradation of indigo carmine dye (C16H8N2Na2O8S2) solution under UV light, and white light. The dye degradation and the kinetic of the reaction were estimated measuring the variation of the dye absorption band as a function of the irradiation time. After calculating and comparing the reaction kinetic constants, it was concluded that using UV light, there is not an appreciable difference of the photocatalytic activity between Bi2O3 andBi2O3:N films, meanwhile we could notice a negative effect in the photocatalytic performance of Bi2O3:Ta films. On the other hand, we observed that when visible light (white light) was used; Bi2O3:N films had a better performance than Bi2O3 films . These results suggest that doping Bi2O3 films might improve the visible-light photocatalytic activity of the material for water treatment applications.

Acknowledgement: The research leading to these results has received funding from the European Community Seven Framework Programme (FP7-NMP-2010-EU-MEXICO) and CONACYT under grant agreements nº 263878 and 125141, respectively. Phocscleen 318977.

FP-10 Characterization of the MgO/GaSe0.5S0.5 Heterojunction Designed for Visible Light Communications
Sabah Alqarni (King Abdulaziz University, Saudi Arabia)

In this study an optoelectronic design is reported and characterized. The device is made of p-type MgO solved in sodium silicate binder and n-type GaSe0.5S0.5 heterojunction. It is described by means of X-ray diffraction, optical absorption and reflection in the incident light wavelength range of 190–1100 nm and by means of dark and 406 nm laser excited current (I)–voltage (V) characteristics. The optical reflectance was also measured as a function of angle of incidence of light in the range of 35–801. The structural analysis revealed no change in the existing phases of the device composers. In addition, it was observed that for pure sodium silicate and for a 67% content of MgO solved in sodium silicate binder (33%), the heterojunction exhibits a valence band shift of 0.40 and 0.70 eV, respectively. The painting of MgO improved the light absorbability significantly. On the other hand, the angle-dependent reflectance measurements on the crystal displayed a Brewster condition at 70o The MgO/ GaSe0.5S0.5 heterojunction exhibited no Brewster condition when irradiated from the MgO side. Moreover, for the crystal and the MgO/ GaSe0.5S0.5 heterojunction, the dielectric spectral analysis revealed a pronounced increase in the quality factor of the device. The I–V characteristics of the device revealed typical optoelectronic properties with high photo-response that could amplify the dark current times when irradiated with 5 mW power laser light. The structural, optical, dielectric and electrical features of the MgO/GaSe0.5S0.5 heterojunction nominate it for use in visible light communication technology.

FP-11 Metallic Nanodots Fabricated by Sputtering in Ultra-thin Ordered Porous Alumina Templates
Maria Kokonou (University of Cyprus, Cyprus); Ibrahim Gunduz (Purdue University, USA); Charalabos Doumanidis (Khalifa University, UAE); Claus Rebholz (University of Cyprus, Cyprus)
Porous alumina is commonly used as templates for the fabrication of nanostructures periodically distributed. Nanowires, -tubes, -rods and -dots are grown inside the pores mainly by electrodeposition and sol-gel techniques, which are appropriate for the high aspect-ratio of the pores. On the contrary, it is very difficult to fill long pores using physical vapor deposition (PVD) techniques, such as evaporation and sputtering, due to the pore-closure effect. The material deposits not only at the bottom of the pores but also at the pore entrance and blocks it very quickly. To fill the pores, the pore diameter to height aspect-ratio must be less than 1:4. In this work, the fabrication of metallic and bimetallic nanodots by sputtering in ultra-thin (~100 nm) porous alumina templates is presented. Ordered, periodic templates with low aspect-ratio pores were fabricated on Al and Si by double anodization of Al in oxalic acid. Cr, Ni and W nanodots (10-70 nm) were formed inside the pores by sputtering in two different ways: to form larger dots (>50 nm), 200 nm of material was sputter deposited to fill completely the pores and also to form a capping layer for mechanical support. Then, the substrate and the porous alumina template were chemically dissolved. To form smaller dots (<50 nm), 5 to 30 nm of material was sputtered inside the pores, before the porous alumina template was chemically dissolved. Successful pore filling was observed in both cases.
Time Period ThP Sessions | Topic F Sessions | Time Periods | Topics | ICMCTF2016 Schedule