Objectives: The primary objective of this investigation is to make a systematic study on the impact of thickness on optical properties, such as energy gap, absorption coefficient, optical density etc., for selenium thin films. Understanding of the band gap energy and its influence on film thickness is of utmost importance in acquiring the intended electrical characterization of semiconducting films. Materials and methods: Ultra-purity selenium (99.99 %) was deposited on glass substrates. During deposition, the glass substrate with its holder were rotated with constant speed to have a smooth coating. Results and discussions: The XRD findings indicate that selenium is amorphous in nature. The optical band gap energy is found to be decreasing form (2.3 to 2eV) with the rise of film thickness in interval (200 to 1000 nm). The band gap energy obeys inverse square law with respect to thickness. Conclusion: We have properly grown thin films of Se below the De Broglie wavelength limit by thermal evaporation in vacuum. The optical density varies directly with film thickness. The absorption coefficients were in the interval (0.5 to 4) × 107m-1. The AFM results confirmed that the Se nano-size increases with the increase in thickness. Both the grain boundaries and sub-grain regions are clearly visible in the SEM micrographs
coeficiente de absorción, banda prohibida, propiedades ópticas de películas finas de SeAbsorption coefficient, band gap, optical properties of Se thin films
 A. A. Al Ghamdi, “Optical band gap and optical constants in amorphous Se96-xTe4Agx thin films,” Vacuum, vol. 80, no. 5, pp. 400–405, 2006. Available: https://doi.org/10.1016/j.vacuum.2005.07.003
 C. Rajashree, A. R. Balu, and V. S. Nagarethinam, Substrate Temperature effect on the Physical properties of Spray deposited Lead sulfide Thin Films suitable for Solar control coatings,” Int. J. ChemTech R., vol. 6, no. 1, pp. 347–360, 2014. Available: https://www.semanticscholar.org/paper/Substrate-Temperature-effect-on-the-Physical-of-for-Rajashree-Balu/06937ef83920219bcd60f1a8d1b02a030159bace
 V. Sivaranjani and P. Philominathan, “Influence of substrate temperature on physical properties of nanostructured Ti Doped In2O3 thin films by a simplified perfume atomizer technique,” Int. J. Thin Films Sci. Technol., vol. 4, no. 3, pp. 219–225, 2015. Available: http://www.naturalspublishing.com/Article.asp?ArtcID=9622
 D. C. Sati, R. Kumar, and R. M. Mehra, “Influence of thickness on optical properties of a: As2Se3Thin Films,” Turk. J. Phys., vol. 30, pp. 519- 527, 2006. Available: https://dergipark.org.tr/en/download/article-file/130769
 C.-C. Kuo, C.-C. Liu, S.-C. He, J.-T. Chang, and J.-L. He, “The influences of thickness on the optical and electrical properties of dual-ion-beam sputtering-deposited molybdenum-doped zinc oxide layer,” J. Nanomater., 2011. Available: https://doi.org/10.1155/2011/140697
 R. M. Krishnan and F. O. Meyer III, “Quantum size effect,” Thin Solid Films, vol. 23, no. 1, pp. 7–13, 1974. Available: https://doi.org/10.1016/0040-6090(74)90212-0
 M. A. Angadi and L. A. Udachan, “The effect of the deposition rate on the electrical resistivity of thin tin films,” Thin Solid Films, vol. 78, no. 3, pp. 299–302, 1981. https://doi.org/10.1016/0040-6090(89)90597-X
 M. A. Angadi and L. A. Udachan, “The effect of substrate temperature on the electrical properties of thin chromium films,” J. Mater. Sci., vol. 16, pp. 1412–1415, 1981.
 M. R. A. Bhuiyan, D. K. Saha, and S. M. Firoz Hasan, “Structural and electrical properties of polycrystalline AgxGa2-xSe2 (0.4 ≤ x ≤ 1.6) thin films,” Indian J. Pure Appl. Phys., vol. 47, pp. 787–792, 2009.
 S. Sankar and K. G. Gopchandran, “Effect of growth parameters on structural, electrical and optical properties of titanium oxide thin films,” Indian J. Pure Appl. Phys., vol. 46, no. 11, pp. 791–796, Nov. 2008. Available: http://nopr.niscair.res.in/handle/123456789/2598
 L. U. Shiva, N. H. Ayachit, L. A. Udachan, A. V. Banagar, S. S. Kolkundi, and S. S. Bhairamadagi, “Influence of substrates on the electrical properties of thin tin films,” Bulgarian J. Phys., vol. 45, no. 1, pp. 35–43, 2018.
 R. Sethi, S. Ahmad, A. Aziz, and A. Majid Siddiqui, “Structural, optical and electrical properties of tin oxide thin films for application as a wide band gap semiconductor,” in AIP Conference Proceedings 1675, 2015. Available: http://doi.org/10.1063/1.4929255
 S. Al-Ani, M. N. Al-Delaimi, A. H. Al-Hamdani, and H. M. Jawher, “Optical and electrical properties of pure and doped amorphous thin selenium films,” Int. J. Electron., vol. 69, no. 1, pp. 87–95, 1990. Available: https://doi.org/10.1080/00207219008920294
 R. Roy, V. S. Choudhary, M. K. Patra, and A. Pandya, “Effect of annealing temperature on the electrical and optical properties of nanocrystalline selenium thin films,” J. Optoelectron. Adv. Mater., vol. 8, pp. 1352–1355, 2006.
 W. C. Tan, “Optical Properties of Amorphous Selenium Films”, M.S. thesis, Dep. Elect. Eng, Univ. Saskatchewan, Saskatchewan, Canada, 2006. Available: https://core.ac.uk/download/pdf/226119535.pdf
 R. Zhang et al., “Visible-light-respnsive t-se nanorods photocatalysts: Synthesis, properties, and mechanism,” RSC Adv., vol. 5, no. 56, pp. 1–9, 2015. Available: https://doi.org/10.1039/C5RA03895B
 K. Tanaka, “Gap states in non-crystalline selenium: Roles of defective structures and impurities,” J. Optoelectron. Adv. Mater., vol. 17, no. 11, pp. 1716–1727, 2017.
 D. S. Deng, N. D. Orf, S. Danto, A. F. Abouraddy, J. D. Joannopoulos, and Y. Fink, “Processing and properties of centimeter-long, in-fiber, crystalline-selenium filaments,” Appl. Phyis. Lett., vol. 96, p. 023102, 2010. Available: https://doi.org/10.1063/1.3275751
 J. R. Scheuermann, A. H. Goldan, O. Tousignant, S. Léveillé, and W. Zhao, “Development of solid-state avalanche amorphous selenium for medical imaging,” Med. Phys., vol. 42, no. 3, pp. 223–1226, 2015. doi:10.1118/1.4907971
 T.-Y. Yu, F.-M. Pan, C.-Y. Chang, J.-S. Lin, and W.-H. Huang, “Thermal stability and photoconductive properties of photosensors with an alternating multilayer structure of amorphous Se and AsxSe1-x,” J. Appl. Phys., vol. 118, p. 044509, 2015. Available: https://doi.org/10.1063/1.4927740
 A. A. El-Amin, A. M. Badr, and F. Abdel-Wahaab, “Optical properties and determination of thermal transformation parameters for Se0.65Te0.35 high reflectance thin films,” Turk. J. Phys., vol. 31, pp. 331–339, 2007. Available: https://www.researchgate.net/publication/253871024_Optical_Properties_and_Determination_of_Thermal_Transformation_Parameters_for_Se065Te035_High_Reflectance_Thin_Films
 H. Singh, “Effects of additives on structural and optical properties of selenium thin films,” Int. J. Comput. Sci. Eng., vol. 7, no. 2, pp. 549–552, 2019. Available: https://doi.org/10.26438/ijcse/v7i2.549552
 S. Sinha, S. K. Chatterjee, J. Ghosh, and A. K. Meikap, “Semiconducting selenium nanoparticles: Structural, electrical characterization, and formation of a back-to-back Schottky diode device,” J. Appl. Phys., vol. 113, no. 12, p. 123704, 2013. Available: https://aip.scitation.org/doi/10.1063/1.4796106
 M. Singh, K. C. Bhahada, and Y. K. Vijay, “Variation of optical band gap in obliquely deposited selenium thin films,” Indian J. Pure Appl. Phys., vol. 43, no. 2, pp. 129–131, 2005. Available: http://nopr.niscair.res.in/handle/123456789/8719
 R. S. Abed, H. S. Sabaa, and M. A. Muhsien, “Effect of deposition angle on optical properties of Selenium thin films,” Int. J. Appl. Innovat. Eng. Man., vol. 2, no. 5, pp. 189–192, 2013. Available: https://www.ijaiem.org/Volume2Issue5/IJAIEM-2013-01-20-036.pdf
 S. A. J. Jassim, A. A. R. A. Zumaila, and G. A. A. A. Waly, “Influence of substrate temperature on the structural, optical and electrical properties of CdS thin films deposited by thermal evaporation,” Results Phys., vol. 3, pp. 173–178, 2013. Available: http://dx.doi.org/10.1016/j.rinp.2013.08.003
 H. S. Shaaker, W. A. Hussain, and H. A. Badran, “Determination of the optical constants and optical limiting of doped malachite green thin films by the spray method,” Adv. Appl. Sci. Res., vol. 3, no. 5, pp. 2940–2946, 2012. Available: https://www.imedpub.com/articles/determination-of-the-optical-constants-and-optical-limiting-of-doped-malachitegreen-thin-films-by-the-spray-method.pdf
 P. H. Soni, J. R. Otia, and C. F. Desai, “Optical band gap of Bi2Te2.8Se0.2 thin films,” Indian J. Eng. Mater. Sci., vol. 11, no. 3, pp. 221–223, 2004. Available: http://nopr.niscair.res.in/handle/123456789/9280
 N. Cicek Bezir, A. Evcin, R. Kayali, M. K. Ozen, and G. Balyaci, “Comparison of pure and doped TiO2 thin films prepared by Sol-Gel Spin-Coating Method,” Acta Physica Polonica A, vol. 132, pp. 620–624, 2017. http://przyrbwn.icm.edu.pl/APP/PDF/132/app132z3p059.pdf
 B. Joseph, K. G. Gopchandran, P. K. Manoj, P. Koshy, and V. K. Vaidyan, “Optical and electrical properties of zinc oxide films prepared by spray pyrolysis,” Bull. Mater. Sci., vol. 22, no. 5, pp. 921–926, Aug. 1999. Available: https://doi.org/10.1007/BF02745554
 A. A. Abdul-Hamead, “Fabrication and AFM characterization of selenium recycled nano-particles by pulse laser evaporation and thermal evaporation,” Mater. Res. Express, vol. 6, no. 12, Mar. 2020. Available: https://iopscience.iop.org/article/10.1088/2053-1591/ab6a50/meta
 N. M. Tashtoush and O. Alkasassbeh, “Determining optical constants of selenium thin films using the envelope method,” Am. J. Appl. Sci., vol. 10, no. 2, pp. 164–171, 2013. Available: https://doi.org/10.3844/ajassp.2013.164.171
 F. Mutar and A. Hemed, “Effect of Thermal Annealing on the Structural, Optical, and Electrical Properties of a-Se Thin Films,” Adv. Phys. Theories Appl., vol. 31, pp. 16–24, 2014. Available: https://www.iiste.org/Journals/index.php/APTA/article/view/12801
 S. A. Jesuraj, S. Devadason, and M. M. D. Kumarc, “Effect of quantum confinement in CdSe/Se multilayer thin films prepared by PVD technique”, Mater. Sci. Semiconduct. Proc., vol. 64, no. 15, pp. 109–114, 2017. Available: https://doi.org/10.1016/j.mssp.2017.03.019
 S. Baco, A. Chik, and F. Md. Yassin, “Study on optical properties of tin oxide thin film at different annealing temperature,” J. Sci. Tech., vol. 4, no. 1, 2012. Available: https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/468
 D.Singh, S. Kumar, R. Thangaraj, and T. S. Sathiaraj, “Influence of thickness on optical properties of a-(Se80Te20)96Ag4 thin films,” Physica B: Condensed Matter, vol. 408, no. 1, pp. 119–125, 2013. Available: https://doi.org/10.1016/j.physb.2012.09.034
 S. Victor Vedanayakam and D. Punyaseshudu, “1/f noise studies on thin films of cadmium oxide”, Mater. Phys. Mech., vol.18, pp. 1–10, 2013. Available: http://www.ipme.ru/e-journals/MPM/no_11813/MPM118_01_vedanayakam.html
 L. C. Nehru, M. Umadevi, and C. Sanjeeviraja, “Studies on Structural, Optical and Electrical Properties of ZnO Thin Films Prepared by the Spray Pyrolysis Method,” Int. J. Mater. Eng., vol. 2, no. 1, pp. 12–17, 2012. Available: http://article.sapub.org/10.5923.j.ijme.20120201.03.html
 N. Kumar, U. Parihar, R. Kumar, K. J. Patel, C. J. Panchal, and N. Padha, “Effect of film thickness on optical properties of tin selenide thin films prepared by thermal evaporation for photovoltaic applications,” Am. J. Mater. Sci., vol. 2, no. 1, pp. 41–45, 2012. Available: http://article.sapub.org/10.5923.j.materials.20120201.08.html
 S. M. Vyas, M. Patel, S. Thakor, and V. Patel, “Optical Properties of Thin Film of Bi2Te3-XSeX (X=0.1&0.5) Compounds,” IJLTEMAS, vol. III, no. V, pp. 166–168, May 2014. Available: https://www.ijltemas.in/DigitalLibrary/Vol.3Issue5/166-168.pdf
 A. M. Karguppikar, and A. G. Vedeshwar, “Thickness dependence of the forbidden energy gap in stibnite (Sb2S3) thin films,” Phys. Lett. A, vol. 126, no. 2, pp. 123–126, 1987. Available: https://doi.org/10.1016/0375-9601(87)90570-6
 M. H. Suhail, “Structural and optical properties of ZnS, PbS, Zn1-xPbxS, ZnxPb1-xS and PbZnxS1-x thin films,” Indian J. Pure Appl. Phys., vol. 50, n. 06, pp. 380–386. 2012. Available: http://nopr.niscair.res.in/handle/123456789/14180
 A. Tumuluri, K. Lakshun Naidu, and K. C. James Raju, “Band gap determination using Tauc’s plot for LiNbO3 thin films,” Int. J.ChemTech Res., vol. 6, no. 6, pp. 3353–3356, 2014. Available: http://sphinxsai.com/2014/vol6_6_ICMCT/4/(3353-3356)ICMCT14.pdf.
 E. I. Rogacheva, S. I. Menshikova, A. Yu Sipatov, and O. N. Nashchekina, “Thickness-dependent quantum oscillations of the transport properties in bismuth selenide thin films,” Thin Solid Films, vol. 684, pp. 31–35, 2019. Available: https://doi.org/10.1016/j.tsf.2019.05.046
 P. H, Soni, S. R. Bhavsar, G. R. Pandya, and C. F. Desai, “Optical band gap of In 0.1Bi 1.9Te 3 thin films,” Indian J. Pure Appl. Phys., vol. 46, no. 11, pp. 806–808, 2008.
 A. S. Hassanien and A. A. Akl, “Influence of composition on optical and dispersion parameters of thermally evaporated non-crystalline Cd50S50−xSex thin films,” J. Alloys Compd., vol. 648, pp. 280–290, 2015. Available: https://doi.org/10.1016/j.jallcom.2015.06.231
 L. Shiva, N. Ayachit, L. Udachan, A. Banagar, S. Kolkundi, and S. Bhairamadagi, “A study on nucleation, growth and grain boundary reflection in thin tin nanofilms,” J. Phys. Conf. Ser., vol. 1186, no. 1, pp. 012006, 2018. Available: https://doi.org/10.1088/1742-6596/1186/1/012006
 F. Gode, S. Guneri, A. Kariper, C. Ulutas, F. Kirmizigul and C. Gumus, “Influence of annealing temperature on the structural, optical and electrical properties of amorphous Zinc Sulphide thin films,” J. Phys. Conf. Ser., vol. 326, p. 012020, 2011. Available: https://doi.org/10.1088/1742-6596/326/1/012020
 S. Elmas, S. Ozcan, S. Ozder, and V. Bilgin, “Influence of annealing temperature on the electrical and optical properties of CdS thin films,” Acta Physica Polonica A, vol. 121, no. 1, pp. 56–58, 2012. Available: https://pdfs.semanticscholar.org/ba52/81dc06023b8b0e5e29f4af58f43de12da5bc.pdf
 A. C. Scheid et al., “Silver nanoparticle thin films deposited on glass surface using an ionic silsesquioxane as stabilizer and as crosslinking agent,” J. Braz. Chem. Soc., vol. 26, no. 5, pp. 1004–1012, 2015. Available: https://doi.org/10.5935/0103-5053.20150066.
 A. Taabouche et al., “Effect of substrates on the properties of ZnO thin films grown by pulsed laser deposition,” Adv, Mater. Phys. Chem., vol. 3, no. 4, pp. 209–213, 2013. Available: https://www.scirp.org/journal/PaperInforCitation.aspx?PaperID=36086
 B. D. Ngom et al., “Structural and optical properties of nano-structured tungsten-doped ZnO thin films grown by pulsed laser deposition,” Appl. Surface Sci., vol. 255, no. 7, pp. 4153–4158, 2009. Available: https://doi.org/10.1016/j.apsusc.2008.10.122
 H. Metin, F. Sat, S. Erat, and M. Ari. “Cadmium Sulphide Thin films grown by CBD: The effect of thermal annealing on the structural, electrical and optical properties,” J. Optoelectron. Adv. Mater., vol. 10, no. 10, pp. 2622–2630, 2008. Available: https://www.researchgate.net/publication/286302595_Cadmium_sulphide_thin_films_grown_by_CBD_The_effect_of_thermal_annealing_on_the_structural_electrical_and_optical_properties
 C. K. Senthil Kumaran et al., “Synthesis and Characterization of Selenium Nanowires,” Int. Schol. Res. Net. Nanotechn., pp.1–4, 2011. Available: https://doi.org/10.5402/2011/589073
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