Impacts of nitric acid oxidation on low-temperature polycrystalline silicon TFTs with high-k gate dielectric

Abstract

In this paper, low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFrs) with HfO2 gate dielectric and nitric acid oxidation pre-treatment is investigated. Significant improvement on on/off current ratio and field effect mobility is observed due to the nitric acid oxidation pre-treatment. An excellent on/off current ratio and subthreshold swing, as well as low threshold voltage and I-off can be achieved without any other hydrogen passivation treatments. These improved performances can be attributed to both the high gate capacitance density using high-k gate dielectric and the good interface quality by nitric acid oxidation of poly-silicon.