Nonlinear Optical Properties of Cd0.8Zn0.2Te Quantum Dot

Introduction: The size tuneable semiconductor quantum dots have been studied thoroughly by the scientific community over the past few years due to their excellent optical and luminescence properties. The semiconductor quantum dot finds the advantages of size tuneable structural, chemical, optical and non-linear properties. The ternary Cd1-xZnxTe have potential tailored properties and an excellent candidate for the luminescence and electronic applications. This includes bio labelling, solar cells, lasers, light-emitting diodes, and optoelectronic devices (1, 2). In the present work composition depended nonlinear properties of Cd1-xZnxTe (x = 0.2) quantum dots in aqueous medium were investigated. Methods: Quantum dots of alloyed Cd1-xZnxTe (x = 0.2) in aqueous medium have been prepared using 3-MPA as the capping agent and sodium tellurite for the source of tellurium in open air conditions. The optical characterization of the quantum dot carried out in an UV-Visible spectrophotometer. The open aperture Z-scan technique with 532 nm continuous wave laser utilized to analyse the intensity depended nonlinear properties of the alloyed Cd0.8Zn0.2Te quantum dot. Results & Discussions: The absorption spectrum showed an excitonic peak around 501 nm. Tauc plot and Urbach plot were utilized to find the optical band gap energy and urbach energy of the Cd0.8Zn0.2Te compounds. The nanoparticle size was calculated using the energy band gap of the quantum dot obtained from Tauc method and the bulk energy bandgap of the Cd0.8Zn0.2Te. The open aperture Z-scan technique performed to obtain the nonlinear absorption of Cd0.8Zn0.2Te quantum dot (3). The transmittance of the samples decreases as the sample approaches the focal point and it increases after departing from the focus. The sharp reduction in the transmittance at the focal point is due to the reverse saturation absorption. The nonlinear absorption coefficient β were found out using the formulation. Conclusions: The nonlinear absorption coefficient of Cd0.8Zn0.2Te quantum dot was found out. The sharp reduction in the intensity towards the focal point and large values of absorption coefficient indicates that the material is well suitable for optical limiting and nonlinear applications. Keywords: CdZnTe quantum dot, Nonlinear absorption, Open aperture Z-scan Acknowledgment: Author Kiran John U. acknowledge KSCSTE, Kerala for the research fellowship. References 1. Balakrishnan J, Preethi LK, Sreeshma D, Jagtap A, Madapu KK, Dhara S, Rao KK, Temperture and Size-depended Photoluminescenece in Colloidal CdTe and CdxZn1-xTe Quantum dots. Journal of Physics D: Applied Physics 2021; 54(14): 145103 2. Al-Rasheedi A, Wageh S, Al-Zhrani E, Al-Ghamdi A, Structural and Optical Properties of CdZnTe Quantum dots Capped with a Bifunctional Molecule. Journal of Materials Science: Materials in Electronics 2017; 28(12): 9114-9125 3. Tripathi SK, Kaur R, Kaur J, Sharma M, Third-order Nonlinear Optical Response of Ag–CdSe/PVA Hybrid Nanocomposite. Applied Physics A 2015; 120(3): 1047-105