Mitigating wakeup effect and improving endurance of ferroelectric HfO_2-ZrO_2 thin films by careful La-doping

摘要

The crystalline structure and electrical response of La-doped HfO2-ZrO2 thin films of which processing temperature did not exceed 400 degrees C were examined, where the La-doping concentration was varied from zero to mol. %. The film structure and associated properties were found to vary sensitively with the minute variation in the La-concentration, where the ferroelectric response at low La-concentration (approximate to 1 mol. %) gradually became antiferroelectric-like for La-concentration approximate to 1. mol. %, which was accompanied by a significant increase in dielectric permittivity. La-doping was found to be very effective in inhibiting the monoclinic phase formation and in decreasing the leakage current. Notably, the high coercive field, which was one of the most significant problems in this material system, could be decreased by similar to 35% at the most promising La-concentration of 0.7 mol. %. As a result, a highly promising field cycling endurance up to 10(11) cycles could be secured while maintaining a high remnant polarization value (= 25 mu/C/cm(2)). This is one of the best results in this field of the authors' knowledge. Published under license by AIP Publishing.