Solution Combustion Synthesis: Low-Temperature Processing for p-Type Cu:NiO Thin Films for Transparent Electronics.

Abstract

Low-temperature solution processing opens a new window for the fabrication of oxide semiconductors due to its simple, low cost, and large-area uniformity. Herein, by using solution combustion synthesis (SCS), p-type Cu-doped NiO (Cu:NiO) thin films are fabricated at a temperature lower than 150 °C. The light doping of Cu substitutes the Ni site and disperses the valence band of the NiO matrix, leading to an enhanced p-type conductivity. Their integration into thin-film transistors (TFTs) demonstrates typical p-type semiconducting behavior. The optimized Cu_5% NiO TFT exhibits outstanding electrical performance with a hole mobility of 1.5 cm² V^-1 s^-1 , a large on/off current ratio of ≈10⁴ , and clear switching characteristics under dynamic measurements. The employment of a high-k ZrO₂ gate dielectric enables a low operating voltage (≤2 V) of the TFTs, which is critical for portable and battery-driven devices. The construction of a light-emitting-diode driving circuit demonstrates the high current control capability of the resultant TFTs. The achievement of the low-temperature-processed Cu:NiO thin films via SCS not only provides a feasible approach for low-cost flexible p-type oxide electronics but also represents a significant step toward the development of complementary metal-oxide semiconductor circuits.