AlN压电薄膜微晶择优取向对其介电常数的影响

本文从声场理论出发,将各晶粒的电位移矢量D视作对有效介电常数有独立贡献的矢量,采用Bond矩阵法进行张量变换,并对各晶粒的贡献进行空间平均,得出AlN压电薄膜微晶择优取向对其介电常数影响的分析结果。

The Effect of Microcrystal Preferred Orientation of AlN Piezoelectric Thin Film on Its Dielectric Constant

It has occasionally been found by the author during experiment that the dielectric constant of the specimen of AlN thin film with c-axis preferred orientation of microcrystal is higher than that of the specimen with poor preferred orientation. The following results have been obtained by using the theory of the acoustic field, taking the electric displacement vector D of each crystal grain as one with independent contribution to the effective dielectric constant, carrying out tensor transformation with the bond matrix method and averaging the contribution of each crystal grain over space:(1) When all the crystal grains are disoriented, (2) When the c-axis of every crystal grain is perpendicular to the film surface,(3) When the c-axis of every crystal grain is parallel to the film surface,If the stress in the film is so small that it can be neglected, the difference between D'3 and D'3 is insignificant. The phenomenon found during experiment that the dielectric constant of the specimen with good microcrystal preferred c-axis orientation is higher can be interpreted as a special case where the internal stress satisfies certain conditions.