UV-assisted nucleation and growth of oxide films from chemical solutions

Abstract

The fabrication of thin oxide films at low temperatures using simple processes has been a significant challenge associated with expanding the potential applications of these materials. Recent developments have demonstrated that the photo-assisted chemical solution deposition (PACSD) process offers a promising means of solving these difficulties, allowing high volume, on-demand production of variable sample sizes using an advantageous wet process. A better understanding of the crystal growth phenomena associated with this process, however, is required to enable various oxide thin films to be prepared using this new concept. Under pulsed ultraviolet (UV) laser irradiation, crystal growth has been confirmed to proceed by near-instantaneous photothermal heating and photochemical effects at the reaction interface. Vacuum UV lamp irradiation is also a useful means of generating oxide nuclei, since it results in effective chemical bond cleavage and simultaneously produces reactive oxidant (O3/O((1)D)) species. In this review, the nucleation and growth mechanisms which occur during the PACSD process are introduced and discussed and we examine the future possible applications of this process.

Laser Irradiation of Metal Oxide Films and Nanostructures: Applications and Advances

“…These oxide films and nanostructures are traditionally synthesized by deposition methods utilizing liquid, gaseous, ionized vapor, or plasma precursors . Among these options, liquid‐precursor‐based synthesis methods are attractive due to such attributes as speed, low temperature, being vacuum‐free, cost effectiveness, and scaling . Wet‐chemical processes, such as the sol–gel technique and metal–organic deposition (MOD), are commonly used for growth of MO thin films.…”

“…Over the past decade, laser irradiation has also been employed to replace the conventional thermal treatment for the nucleation and growth of functional MO thin films at low temperatures and on short time scales . Absorption of laser radiation results in rapid photothermal and/or photochemical effects, which influences the crystallization and growth kinetics of thin films.…”

“…Absorption of laser radiation results in rapid photothermal and/or photochemical effects, which influences the crystallization and growth kinetics of thin films. Prior studies have demonstrated the evolution of polycrystalline, textured, and epitaxial microstructures of diverse MO films (e.g., tin‐doped indium oxide (ITO), Ga 2 O 3 , ZnO, TiO 2 , VO 2 , WO 3 , BaSrTiO 3 (BST), Pb(Zr,Ti)O 3 (PZT), La 1− x Sr x MnO 3 (LSMO)) deposited by methods such as chemical solution deposition (CSD), pulsed‐laser deposition (PLD), and sputtering . The large temperature gradients and high diffusion rates during laser processing lead to epitaxial growth rates that are orders of magnitude larger and effective heating times much shorter than that for conventional thermal treatment .…”

Integration effect of O2‐plasma to an excimer‐laser‐assisted metal organic deposition process for functionalization of photoelectrodes

“…Recently, there is a progress in low‐temperature coating technologies for metal oxides; for example, high‐crystallinity metal oxides can be now coated at a low temperature using photo‐MOD method in which precursor films are crystallized by excimer laser irradiation . Particularly, we developed a photo‐MOD technique for lamination of photoelectrodes, and demonstrated that crystalline TiO 2 layer can be composited on Cu 2 O photoelectrodes using this technique .…”

“…Recently, there is a progress in low-temperature coating technologies for metal oxides; for example, high-crystallinity metal oxides can be now coated at a low temperature using photo-MOD method in which precursor films are crystallized by excimer laser irradiation. [3][4][5][6][7] Particularly, we developed a photo-MOD technique for lamination of photoelectrodes, and demonstrated that crystalline TiO 2 layer can be composited on Cu 2 O photoelectrodes using this technique. 7 However, when TiO 2 is crystallized by excimer laser irradiation, oxidation of Cu 2 O into CuO occurs at the same time, and it is difficult to fully prevent oxidation of the underlying Cu 2 O by only means of photo-MOD process.…”