Single Band Electronic Conduction in Hafnium Oxide Prepared by Atomic Layer Deposition

Current-voltage and capacitance-voltage measurements on MOS structures with hafnium gate oxide (HfO2) prepared by atomic layer deposition were conducted to determine the dominant current conduction in the Al/HfO2/Si structure. In n-type substrate MOS structures, electron injection from Al into HfO2is observed when the Al electrode is negatively biased. Whereas in p-type MOS capacitors at negative biasing, no hole injection can be detected and the current in the insulator is again due to the electron injection from Al. These results unambiguously indicate that in both p- and n- type substrates and at both biasing polarities only electronic current conduction in the Si/HfO2/Al is significant.