Ta-doped modified Gd2O3 film for a novel high dielectric constant k gate dielectric

Gadolinium oxide (Gd2O3) film has potential as a candidate gate dielectric to replace HfO2. In this work, we provide a simple method by trace Ta (∼1%) doping to significantly improve the dielectric properties of Gd2O3 film. And effects of annealing temperatures of Ta-doped Gd2O3 (GTO) films are investigated in detail. Results show that GTO film annealed at 500 °C exhibits excellent performance as a novel gate dielectric material for integrated circuit, showing a small surface roughness of 0.199 nm, a large band gap of 5.45 eV, a high dielectric constant (k) of 21.2 and a low leakage current density (Jg) of 2.10 × 10−3 A/cm2. All properties of GTO films are superior to pure Gd2O3 films and these GTO films meet the requirements for next-generation gate dielectrics. In addition, impedance spectrum is first used to analyze the equivalent circuit of GTO based metal-oxide-semiconductor (MOS) capacitors, which represents a new insight to understand observed electrical behaviors.