Metal-oxide-semiconductor capacitors with Tm2O3 high-k gate dielectrics were fabricated. Based on the I-V measurements of Al/Tm2O3/Si devices at different temperatures, the leakage current mechanisms for Al/Tm2O3/Si stack structures have been extracted. The results reveal that the dominant conduction mechanisms under substrate injection and gate injection are Schottky emission and Frenkel-Poole conduction, respectively. The determined Schottky barrier height between Tm2O3 and Si is 1.68 +/- 0.2 eV. The further I-V measurements of Fowler-Nordheim tunneling characteristics at 77 K is conducted to the conduction-band offset at the interfaces of Al/Tm2O3 and Pt/Tm2O3, which are 2.95 eV and 1.75 eV, respectively. The energy band diagrams of the Al (Pt)/Tm2O3/Si stack structures were obtained from the above results, which show that Tm2O3 is a promising candidate for use as high-k gate dielectric on high-performance substrates. (C) 2016 Elsevier B.V. All rights reserved.