Polarity inversion in aluminum nitride thin films under high sputtering power

The authors have investigated the influence of sputtering power on the piezoelectric response of aluminum nitride (AlN) thin films prepared on titanium nitride bottom electrodes. The piezoelectric response strongly depends on the sputtering power. The polar inversion was found by piezoresponse force microscopy. The polarity gradually changes from the N polarity to Al polarity with increasing sputtering power. The piezoelectric response of the films changes from −2.7to+4.3pC∕N with increasing sputtering power from 100to500W. Furthermore, the polarity inversion from the N polarity to Al polarity is observed by increasing sputtering power during growth.

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