Photoluminescence from Undoped SnO₂ Thin Films by Chemical Vapor Deposition

Tin dioxide (SnO₂), as a direct band gap semiconductor with the reported bandgap value of 3.6 eV, has been widely applied in various applications, such as optoelectronics, photocatalysis, gas sensing and energy conversion devices (for example perovskite solar cells) [1]. Due to the high electron mobility, SnO₂ thin film manufactured by deposition methods is usually used as electron transport layer in optoelectronics, making it a curial role in these devices. Therefore, the understanding of fundamental properties of SnO₂ thin film is important to further promote its functions. In our previous studies, we have reported the possibility to conduct nanoscale engineering to deposit unique Sn-based nanostructures by using nanostructured/planar silicon surfaces [2-3]. Here, we report a strong photoluminescence effect was observed by a metal organic chemical vapor deposition (MOCVD) process. Under ultraviolet radiation in the wavelength range between 250-325 nm, the deposited SnO₂ thin film exhibited a broad orange photoluminescence near 600 nm or blue plotoluminescenc near 400 nm by different excitation source. Extensive surface and bulk characterization techniques such as electron microscopy, XRD, and synchrotron radiation based XPS and NEXAFS techniques were applied to study the atomic and electronic structure features of the deposited SnO₂ thin film. Furthermore, low-temperature photoluminescence and grazing-incidence small-angle scattering techniques were applied to understanding the origins of the observed photoluminescence. This study revealed deep fundamental understanding about the relationship between the structural features of SnO₂ thin film and its optoelectronic properties, providing theoretical basis for the further applications of SnO₂ in various devices.<br/>[1] P. Liu and V. Sivakov, <i>Tin/Tin Oxide Nanostructures: Formation, Application, and Atomic and Electronic Structure Peculiarities, <b>Nanomaterials</b> </i>13(17), 2391 (2023).<br/>[2] P. Liu, A. Schleusener, G. Zieger, A. Bochmann, M. A. van Spronsen, and V. Sivakov, <i>Nanostructured Silicon Matrix for Materials Engineering,</i> <b><i>Small</i> </b>19, 2206318 (2023).<br/>[3] S. Turishchev, A. Schleusener, O. Chuvenkova, E. Parinova, P. Liu, Maxim Manyakin, S. Kurganskii, and V. Sivakov, <i>Spectromicroscopy Studies of Silicon Nanowires Array Covered by Tin Oxide Layers</i>, <b><i>Small</i></b><i> </i>19, 2206322 (2023).