Soluble oxide gate dielectrics prepared using the self-combustion reaction for high-performance thin-film transistors

We report the fabrication of high-performance metal oxide thin-film transistors (TFTs) with AlOx gate dielectrics using combustion chemistry in a solution process to provide energy to convert oxide precursors into oxides at low temperatures. Our self-combustion system utilizing two Al precursors as a fuel and an oxidizer is systematically compared with conventional combustive Al precursors with urea in terms of combustion efficiency and dielectric properties. AlOx gate dielectric layers are spin-coated from a solution of combustive AlOx precursors in 2-methoxyethanol and annealed at 250 degrees C. In this process, organic compounds can be introduced to improve the resulting layer morphology. The thermal behaviors of the self-combustive AlOx precursors are investigated and compared with those of noncombustive AlOx precursors and combustive urea-AlOx precursors to evaluate the generation of exothermic heat at a relatively low annealing temperature. The AlOx dielectrics prepared from selfcombustive precursors have uniform and smooth surfaces, low leakage current densities, and high dielectric constants above 8.7. They also exhibit excellent insulating properties and no breakdown at high electric fields. Furthermore, the ZnO TFTs prepared to confirm the operation of the AlOx gate dielectrics show a good mobility of 24.7 cm(2) V-1 s(-1) and an on/off ratio of 10(5). It is believed that the AlOx dielectrics prepared using the self-combustion reaction at a low temperature can form a good interface facilitating the growth of desirable ZnO crystal structures, which leads to a considerable improvement in ZnO TFT performance.