Low temperature and rapid formation of high quality metal oxide thin film via a hydroxide-assisted energy conservation strategy

Abstract

Metal oxide thin films made from a sol–gel solution process are promising candidates for stable, low cost, and high performance electronic devices. Reducing the thermal budget required for their crystallization process can relax the fabrication limitation and expand their possible applications. We show that with the addition of an adequate amount of tetramethylammonium hydroxide (TMAOH) in the precursor solution, the activation energy of the sol–gel reaction can be reduced by about 50%. Using this strategy, not only can the required thermal treatment time and temperature of the sol–gel reaction be significantly reduced but also the quality of the film can be improved. The enhanced reaction rate can be ascribed to the presence of hydroxyl anions, which facilitate the formation of the metal hydroxide and the subsequent metal oxide. Additionally, the strategy developed here can be applied to multiple kinds of metal oxides. By this method, the processing temperature can be lowered by at least 50 °C and the time can be shortened by half for the fabrication of electronic devices such as thin film transistors and photovoltaics. Our results open up a new paradigm to fabricate highly crystalline metal oxide thin films quickly at an energy saving low temperature using the solution process.