Thermal stability of interface dipole modulation in atomic layer-deposited HfO2/SiO2 multi-stack structures

In this paper, we report on an interface dipole modulation (IDM) loss occurring in HfO2/atomically thin TiO2/SiO2 stack structures prepared by atomic layer deposition (ALD). The IDM characteristic, which is observed as a capacitance–voltage (C–V) hysteresis curve, disappears when the temperature during ALD or post-deposition annealing exceeds its respective critical temperatures, even though the HfO2/SiO2 stack structure is maintained. We found a correlation between Ti suboxide formation and IDM loss and speculated the effect of impurities and defects introduced during the ALD process on IDM operation.