The Optical Properties of Europium-doped Zinc Selenide Films

Authors D.M. Jeroh, A.J. Ekpunobi , D.N. Okoli

Nnamdi Azikiwe University, Anambra State, Nigeria

Issue Volume 12, Year 2020, Number 5
Dates Received 01 May 2020; revised manuscript received 15 October 2020; published online 25 October 2020
Citation D.M. Jeroh, A.J. Ekpunobi, D.N. Okoli, J. Nano- Electron. Phys. 12 No 5, 05006 (2020)
PACS Number(s) 78.66.Hf, 73.50.Pz
Keywords Zinc selenide, Europium, Nanofilms (2) , Spray pyrolysis (9) , Optical studies.

Europium-doped ZnSe films were sprayed on glass substrates electrostatically. Keeping other deposition parameters such as flow rate of precursor solution, spray volume, voltage and distance of nozzle to substrate constant, temperature was varied from about 300 C and 400 C with an interval of 25 degrees. Optical studies at different temperatures are presented. Thickness of the films obtained by surface profile indicates nanosizes of 50, 100, 150, 75 and 60 nm in the considered temperature range. Optical studies reveal high transparency, very minimal absorption and reflection characteristics of ZnSe:Eu films in the visible region. Absorption peaks visible at 250 nm suggest the occurrence of defect state near the band edge. Large absorption coefficient suggesting evidence of high density of states for ZnSe:Eu is observed. High transmittance results suggest the films suitability in coating materials that are required to exhibit high transparency for laser applications, while low reflectance values and large refractive index reveal the films could be applicable in solar cell coatings that require high efficiency and in manufacturing optoelectronic devices. Higher optical conductivity at photon energies above 3 eV is evident. Steep increase in extinction coefficient with photon energy indicates the probability of raising the electron transfer across the mobility gap with high photon energy and greater attenuation of light. Band gap investigation of ZnSe:Eu films reveals a strong blue-shift (3.01 eV to 3.12 eV) from the bulk ZnSe (2.72 eV) band gap.

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