A novel reduction approach for fabrication of transparent conducting fluorine and tin doped indium oxide thin film with low sheet resistance

Abstract

Surface and interface engineering of fluorine and tin doped indium oxide thin film at mild conditions to modulate optoelectronic properties is of great significance. Herein, a simple, low-cost solgel-spin-coating method was used to create a reproducible, scalable, stable, transparent, and conducting tin fluorine doped indium oxide thin film (FTIO thin film). To improve the electrical and optical properties of the thin film, a novel chemical reduction process was developed that did not require any reducing gas, inert atmosphere, and high temperature annealing. The chemical reduction time and concentration of NaBH4-dependent analysis shows a big drop (similar to 83%) in sheet resistance, due to increased oxygen vacancy in thin film. This increased oxygen vacancy was confirmed from XPS analysis. The treated FTIO thin film show lower resistivity (rho = 0.95 x 10(-3) Omega cm), highest figure of merit (0.001 Omega(-1)), roughness of 19.53 angstrom, and sheet resistance of 193 +/- 3 Omega/sq, when compared to all other the solgel-spin-coating thin film process testified to date. To test the general applicability of the proposed reduction technique, it was applied to commercially available ITO thin film, and found to reduce sheet resistance by more than 53% (<= 7 +/- 1 Omega/sq) of the initial sheet resistance. Compared to other common post-treatment approaches, the proposed methodology reduces sheet resistance and could satisfy the demands of most real applications.