Piezoelectric Coefficient Measurement of AIN Thin Films at the NanometerScale by Using Piezoresponse Force Microscopy

摘要

In this research, aluminum nitride (AlN) thin films were fabricated on Au/Si_3N_4/Si structure by using a radio-frequency sputtering system. The film's properties were measured using high-resolution X-ray diffraction, atomic force microscopy, and piezoresponse force microscopy (PFM) with a lock-in-amplifier. The value of the full width at half maximum indicated that the AlN thin film was well formed along the c-direction and had a highly (002) preferred orientation. Through the PFM measurements, the images of the piezoelectric dynamics were confirmed, and the strain-electric field hysteresis loops for each indexed grain was measured using the conductive tip of the PFM without a top metallic electrode layer. From these loops and for each grain, the strain behavior and the effective piezoelectric coefficient d_(33eff) were measured at the nanometer scale, and the real piezoelectric coefficient d_(33) was calculated from the d_(33eff). The d_(33) value wasfound to lie in the range 1.33 to 8.93 pm/V along the grain positions, and the average d_(33) value was calculated as 4.81 pm/V.