Еволюція структури та оптичних властивостей тонких плівок Ga-легованого ZnO, отриманих методом магнетронного напилення з різною потужністю: експеримент та моделювання DFT + U

• Date: 2025
• Main Authors: Shulyma, S.I., Sukhenko, I.V., Kasyanenko, V.Kh., Karbivskyy, V.L., Kurgan, N.A., Shvachko, N.K., Zaika, V.V., Moskaliuk, V.O., Puzko, O.A.
• Format: Article
• Language: English; Ukrainian
• Published: Publishing house "Academperiodika" 2025
• Subjects: ZnO; радiочастотне магнетронне напилення; DFT; морфологiя; прозорiсть; тонкi плiвки
• Online Access: https://ujp.bitp.kiev.ua/index.php/ujp/article/view/2023674
• Journal Title: Ukrainian Journal of Physics

The effect of radiofrequency magnetron sputtering power on the morphology and optical properties gallium-doped ZnO (GZO) thin films has been investigated. It is found that the sputtering power increasing leads to a decreasing in the size of clusters on the film surface and the thickness of the crystallite columnar structure. It is shown that the optical bandgap decreasing may be due to the appearance of interstitial defects in the crystal lattice. Despite maintaining, a constant weight ratio of ZnO and Ga in the initial target mixture, an Ga concentration increasing in GZO thin films is observed for higher sputtering powers. The formation mechanism for GZO thin films under increasing magnetron sputtering power is proposed. It is associated with the appearance of Zn and O interstitial inclusions in the ZnO crystal lattice. Density functional theory (DFT) calculations (with Hubbard correction, DFT + U) show that the increased Ga concentration does not cause a narrowing of the optical band gap. Instead, an increase in the Ga content leads to the appearance of additional electronic states in the valence band (–5.0 eV), which is associated with Zn 3d and O 2p hybridization with Ga 4s and Ga 4p states, a Zn 3d and O 2p energy levels position changing due to changes in interatomic distances and bond symmetry, and a redistribution of the electron density around Ga atoms.