Effect of Lanthanum Doping on the Structural, Morphological, and Optical Properties of Spray-Coated ZnO Thin Films †

Document Type

Article

Publication Title

Engineering Proceedings

Abstract

In recent years, transparent conducting oxide semiconductor materials have found applications in both science and technology, especially in the areas of semiconductors, optoelectronics, and a wide range of energy efficiency devices. These TCO materials are the building blocks of various optoelectronic devices, such as transparent thin-film transistors, solar cells, and light-emitting diodes. This work concentrates on the structure, morphology, and optical properties of ZnO and Zn0.95La0.05O thin films at 673 K using a chemical spray technique. The polycrystalline nature and wurtzite structure of ZnO were confirmed by using XRD analysis with preferred growth along the (1 0 1) plane. The Zn0.95La0.05O deposits showed maximum crystallinity of 15.4 nm and a strain value of 2.4 × 10−3. The lattice constants increased for lanthanum-doped ZnO thin films due to the ionic radii mismatch of the doping material, which causes lattice expansion. Fibrous morphology was observed for ZnO, and a mixed structure of grains and fibers was observed for Zn0.95La0.05O films, which confirms the insertion of La3+ into the Zn2+ position. The Zn0.95La0.05O deposits showed transmittance above 80% due to the increased crystalline quality and a bandgap of 3.32 eV. The photoluminescence spectra showed peaks corresponding to e-h recombination, zinc defects (Zni and Ozn), and oxygen vacancy (Oi and Vo). The lanthanum-doped ZnO films showed increased band-edge emission and decreased defect-related peaks due to the increased crystalline quality. Hence, the doping of La3+ ions into a ZnO lattice enhances the crystalline quality and increases the transparency of the host ZnO matrix, which is suitable for optoelectric device applications.

DOI

10.3390/engproc2023059032

Publication Date

1-1-2023

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