Zirconium oxide (ZrO2) is considered as a potential replacement for SiO2 due to its high dielectric constant. The Al/ZrO2/p-Si metal-insulator-semiconductor capacitors were fabricated. The electrical conduction mechanism in zirconium oxide (ZrO2) thin films as a function of temperature T and electric field E was studied. The temperatures measured were 77 K and from 300 to 450 K. With the Al electrode under negative bias, the conduction mechanism in the electric field of 2.3 MV/cm < E < 5 MV/cm and at the temperature 77 K is found to be Fowler-Nordheim tunneling emission. The extracted barrier height between Al and ZrO2 is 1.12 eV. At the electric field of 1.5 MV/cm < E < 4 MV/cm and temperatures of 300 K < T < 450 K, the electrical conduction is dominated by tunnel emission of trapped electrons with an extracted trap barrier height of 0.19 eV at 300 K. The trap barrier height decreases as the temperature increases. This Al/ZrO2 barrier height decreases linearly with temperature with a slope of about -7.0 x 10(-4) eV/K. The lowering of the barrier height is explained by bandgap reduced with increasing temperature. (c) 2005 The Electrochemical Society.