Band gap enhancement and electrical properties of La2 O3 films doped with Y₂ O₃ as high- k gate insulators

In this study, we prepare the well crystallized La₂ O ₃ films by doping Y₂ O₃ with different contents (La2-x Yx O3) and examine the dielectric and electrical properties of La _2-x Yx O₃ films experimentally. It is found that the optical band gap of La_2-x Y_x O₃ film increases with the increase in Y content (x) monotonically. Furthermore, a low leakage current of about 10-5 A/ cm2 (equivalent oxide thickness: 1 nm) when the gate voltage is 1 V larger than the flat band voltage, and good capacitance-voltage characteristics in Au/ La_2-x Y_x O₃ /Si metal-insulator-semiconductor capacitors are observed. Our results also indicate that Pt/ La_2-x Y_x O₃ /Au metal-insulator-metal capacitor shows a low leakage current and a small voltage dependence of the capacitance.