Electrical conduction mechanism in high-dielectric-constant ZrO 2 thin films

Abstract

The electrical conduction mechanism in zirconium oxide (ZrO 2) thin films as a function of temperature T and electric field E was studied. Al/ZrO 2/p-Si metal–insulator–semiconductor (MIS) capacitors were fabricated. With the Al electrode biased negative, the conduction mechanism in the electrical field of 0.81 MV/cm < E < 1.40 MV/cm and in the temperature range of 375 K < T < 450 K is found to be modified Schottky emission. The intrinsic barrier height between Al and ZrO 2 is 1.06 eV. At higher electrical fields of 1.50 MV/cm < E < 2.25 MV/cm and higher temperatures of 375 K < T < 450 K, the electrical conduction is dominated by modified Poole–Frenkel emission. The extracted trap barrier is 0.83 eV. With the Al electrode biased positive, the conduction mechanism is found to be Schottky emission at the electrical field 0.20 MV/cm < E < 0.60 MV/cm and higher temperature range of 425 K < T< 450 K. The barrier height between Si and ZrO 2 is 1.0 eV. Based on these results, an energy band diagram of the Al/ZrO 2/p-Si system is proposed.