Design, Fabrication and Characterization of n-Si Columnar Structures for Solar Cell Applications

Author(s): Aysegul Develioglu*, Levent Trabzon, Yunus Alphan

Journal Name: Nanoscience & Nanotechnology-Asia

Volume 10 , Issue 1 , 2020

DOI : 10.2174/2210681208666181019123035

  Journal Home
Become EABM
Become Reviewer

Graphical Abstract:


Abstract:

Background: Glancing Angle Deposition (GLAD) provides oblique deposition and substrate motion to engineer thin film microstructures in three dimensions on nano scale. Using this technique zigzag, chevrons, staircase, post, helical and various type of nanostructures including 3-D multilayers can be obtained from various metals with controllable morphologies. The aim of the study is to increase surface porosity and junction using GLAD method area for thin film solar cells and therefore to increase p-n junction area. This provides efficient charge separation and strong light absorption.

Methods: Glancing angle deposition using e-beam evaporation technique has been employed to create 3- D silicon nano-structures on the surface. Al and Ag contact layers were deposited by thermal evaporation technique. Hole-conductor polymer PEDOT: PSS was spin coated onto n type silicon thin film. Reflectance spectra were measured using UV-VIS spectroscopy. Scanning electron microscopy was used to image surface and cross-section with and without PEDOT: PSS. Also, transmission spectra of PEDOT: PSS was measured using UV-VIS spectroscopy. Surface wettability properties and contact angles of silicon samples were measured by contact angle measurement with water.

Results: Columnar structures possess less reflection compared to the flat surface depending on surface porosity. This phenomenon shows that these structures can be used as anti-reflection coatings for solar cells and optical devices to decrease reflectivity and increase light harvesting with higher efficiency. Contact angle decreases when surface roughness increases therefore we can see that columnar structures are more hydrophilic compared to dense films. Flat silicon has 98° contact angle while columnar structures have 71° and 61°. PEDOT: PSS exhibits high transparency in the range from 200 to 1100 nm of wavelength of light, which resembles to solar radiation inside the atmosphere. Also, SEM images of the samples show that silicon columnar structures form better contact with PEDOT: PSS than flat surface.

Conclusion: GLAD technique has been used to achieve homogenous rough surface by e-beam evaporation. Both cross-sectional and top-view SEM images show that columnar structures have higher porosity than flat surfaces. The response of UV-VIS spectroscopy shows that columnar structures have less reflection due to highly porous surface. With increasing incident flux angle, antireflection property of the surfaces was enhanced by surpassing the surface reflection. Due to the reduced hydrophobicity of porous structures, organic polymer can be distributed homogenously in between the columnar structures with increased p-n junction interface area. PEDOT: PSS is highly conductive, and it is highly transparent material in the range of the wavelength typically seen in the solar radiation. This makes it easier for light to reach to Si interface to generate electrons and holes. These results provide better understanding of Si- based heterojunction solar cells efficiency improvement with surface modification. This study also shows dependency of optical and electrical activity to surface geometry and surface porosity.

Keywords: Structured Thin Films (STFs), photovoltaics, Scanning Electron Microscopy (SEM), Glancing Angle Deposition (GLAD), thin film microstructures, Sculptured Thin Films (STF).

[1]
Robbie, K.; Sit, J.C.; Brett, M.J. Advanced techniques for glancing angle deposition. J. Vac. Sci. Technol. B Microelectron. Nanometer Struct. Process. Meas. Phenom., 1998, 16(3), 1115-1122.
[2]
Robbie, K.; Beydaghyan, G.; Brown, T.; Dean, C.; Adams, J.; Buzea, C. Ultrahigh vacuum glancing angle deposition system for thin films with controlled three-dimensional nanoscale structure. Rev. Sci. Instrum., 2004, 75(4), 1089-1097.
[3]
Oliva-Ramírez, M.; Gil-Rostra, J.; Yubero, F.; González-Elipe, A.R. Robust polarization active nanostructured 1D Bragg Microcavities as optofluidic label-free refractive index sensor. Sens. Actuators B Chem., 2018, 256, 590-599.
[4]
Singh, A.; Sharma, A.; Tomar, M.; Gupta, V. Growth of highly porous ZnO nanostructures for carbon monoxide gas sensing. Surf. Coat. Tech., 2018, 343, 49-56.
[5]
Ollitrault, J.; Martin, N.; Rauch, J.Y.; Sanchez, J.B.; Berger, F. Improvement of ozone detection with GLAD WO3 films. Mater. Lett., 2015, 155, 1-3.
[6]
Song, Y.G.; Shim, Y.S.; Kim, S.; Han, S.D.; Moon, H.G.; Noh, M.S.; Kang, C.Y. Downsizing gas sensors based on semiconducting metal oxide: Effects of electrodes on gas sensing properties. Sens. Actuators B Chem., 2017, 248, 949-956.
[7]
Briley, C.; Mock, A.; Korlacki, R.; Hofmann, T.; Schubert, E.; Schubert, M. Effects of annealing and conformal alumina passivation on anisotropy and hysteresis of magneto-optical properties of cobalt slanted columnar thin films. Appl. Surf. Sci., 2017, 421, 320-324.
[8]
Zhou, W.; Brock, J.; Khan, M.; Eid, K.F. Oblique angle deposition-induced anisotropy in Co2FeAl films. J. Magn. Magn. Mater., 2018, 456, 353-357.
[9]
El Beainou, R.; Salut, R.; Robert, L.; Cote, J.M.; Potin, V.; Martin, N. Anisotropic conductivity enhancement in inclined W-Cu columnar films. Mater. Lett., 2018, 232, 126-129.
[10]
Daza, L.G.; Canché-Caballero, V.; Díaz, E.C.; Castro-Rodríguez, R.; Iribarren, A. Tuning optical properties of CdTe films with nanocolumnar morphology grown using OAD for improving light absorption in thin-film solar cells. Superlattices Microstruct., 2017, 111, 1126-1136.
[11]
Gupta, M.C.; Ungaro, C.; Foley, J.J.; Gray, S.K. Optical nanostructures design, fabrication, and applications for solar/thermal energy conversion. Sol. Energy, 2018, 165, 100-114.
[12]
Karthick, P.; Vijayanarayanan, D.; Sridharan, M.; Sanjeeviraja, C.; Jeyadheepan, K. Optimization of substrate temperature and characterization of tin oxide based transparent conducting thin films for application in dye-sensitized solar cells. Thin Solid Films, 2017, 631, 1-11.
[13]
Fu, Y.Q.; Luo, J.K.; Nguyen, N.T.; Walton, A.J.; Flewitt, A.J.; Zu, X.T.; Du, H. Advances in piezoelectric thin films for acoustic biosensors, acoustofluidics and lab-on-chip applications. Prog. Mater. Sci., 2017, 89, 31-91.
[14]
Kiema, G.K.; Jensen, M.O.; Brett, M.J. Glancing angle deposition thin film microstructures for microfluidic applications. Chem. Mater., 2005, 17(16), 4046-4048.
[15]
Barranco, A.; Borras, A.; Gonzalez-Elipe, A.R.; Palmero, A. Perspectives on oblique angle deposition of thin films: From fundamentals to devices. Prog. Mater. Sci., 2016, 76, 59-153.
[16]
Guvendik, S.; Trabzon, L.; Ramazanoglu, M. The effect of Si nano-columns in 2-D and 3-D on cellular behaviour: Nanotopography-induced CaP deposition from differentiating mesenchymal stem cells. J. Nanosci. Nanotechnol., 2011, 11(10), 8896-8902.
[17]
Kennedy, S.R.; Brett, M.J. Porous broadband antireflection coating by glancing angle deposition. Appl. Opt., 2003, 42(22), 4573-4579.
[18]
Messier, R; Gehrke, T.; Frankel, C.; Venugopal, V. C.; Otano, W.; Lakhtakia, A. Engineered sculptured nematic thin films. J. Vacuum Sci. Technol. A Vacuum Surfaces Films, 1997, 15(4), 2148-2152.
[19]
Rice, C.; Mock, A.; Sekora, D.; Schmidt, D.; Hofmann, T.; Schubert, E.; Schubert, M. Control of slanting angle, porosity, and anisotropic optical constants of slanted columnar thin films via in situ nucleation layer tailoring. Appl. Surf. Sci., 2017, 421, 766-771.
[20]
Kahn, S.B.; Hou, M.; Shuang, S.; Zhang, Z. Morphological influence of TiO2 nanostructures (nanozigzag, nanohelics and nanorod) on photocatalytic degradation of organic dyes. Appl. Surf. Sci., 2017, 400, 184-193.
[21]
Sumigawa, T.; Chen, S.; Yukishita, T.; Kitamura, T. In situ observation of tensile behavior in a single silicon nano-helix grown by glancing angle deposition. Thin Solid Films, 2017, 636, 70-77.
[22]
Tokas, R.B.; Jena, S.; Misal, J.S.; Rao, K.D.; Polaki, S.R.; Pratap, C.; Udupa, D.V.; Thakur, S.; Kumar, S.; Sahoo, N.K. Study of ZrO2 thin films deposited at glancing angle by radio frequency magnetron sputtering under varying substrate rotation. Thin Solid Films, 2018, 645, 290-299.
[23]
Ohring, M. The materials science of thin films; Academic Press: San Diego, 1992, pp. 115-116.
[24]
Hawkeye, M.M.; Brett, M.J. Glancing angle deposition: Fabrication, properties, and applications of micro-and nanostructured thin films. J. Vacuum Sci. Technol. A Vacuum Surfaces Films, 2007, 25(5), 1317-1335.
[25]
Broughton, J.N.; Brett, M.J. Electrochemical capacitance in manganese thin films with chevron microstructure. Electrochem. Solid-State Lett., 2002, 5(12), A279-A282.
[26]
Suzuki, M.; Taga, Y. Numerical study of the effective surface area of obliquely deposited thin films. J. Appl. Phys., 2001, 90(11), 5599-5605.
[27]
Sazideh, M.R.; Dizaji, H.R.; Ehsani, M.H.; Moghadam, R.Z. Modification of the morphology and optical properties of SnS films using glancing angle deposition technique. Appl. Surf. Sci., 2017, 405, 514-520.
[28]
He, L.; Jiang, C.; Wang, H.; Lai, D. Simple approach of fabricating high efficiency Si nanowire/conductive polymer hybrid solar cells. IEEE Electron Device Lett., 2011, 32(10), 1406-1408.
[29]
Can, M.F.; Guvendik, S.; Benli, B.; Trabzon, L.; Kizil, H.; Celik, M.S. Predicting the extent of hydrophilicity on Si nano-column surfaces. Materialwissenschaft und Werkstofftechnik., 2012, 43(5), 366-372.
[30]
Khranovskyy, V.; Ekblad, T.; Yakimova, R.; Hultman, L. Surface morphology effects on the light-controlled wettability of ZnO nanostructures. Appl. Surf. Sci., 2012, 258(20), 8146-8152.
[31]
Kurihara, K.; Suzuki, Y.; Suto, K.; Shiba, N.; Nakano, T.; Tominaga, J. Wettability control using large-area nanostructured film. Microelectron. Eng., 2010, 87(5-8), 1424-1427.
[32]
An, T.; Deng, X.; Liu, S.; Wang, S.; Ju, J.; Dou, C. Growth and roughness dependent wetting properties of CeO2 films prepared by glancing angle deposition. Ceram. Int., 2018, 44(8), 9742-9745.
[33]
Abdi, F.; Savaloni, H.; Placido, F. Influence of number of pitches and substrate on the nanostructure and optical properties of ZnS helical sculptured thin films. Opt. Commun., 2016, 380, 69-78.


Rights & PermissionsPrintExport Cite as

Article Details

VOLUME: 10
ISSUE: 1
Year: 2020
Published on: 23 January, 2020
Page: [74 - 79]
Pages: 6
DOI: 10.2174/2210681208666181019123035
Price: $25

Article Metrics

PDF: 12
HTML: 4



Most Downloaded Article(s)