Experimental determination of the electro-acoustic properties of thin film AlScN using surface acoustic wave resonators
Experimental determination of the electro-acoustic properties of thin film AlScN using surface acoustic wave resonators
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DOI：
10.1063/1.5094611
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发表时间：
2019-08-21
影响因子：
3.2
通讯作者：
Ambacher, Oliver
中科院分区：
文献类型：
--
作者：
Kurz, Nicolas;Ding, Anli;Ambacher, Oliver
在这项工作中，所有电声材料参数，即，弹性，压电，和介电系数，以及质量密度，实验确定为纤锌矿氮化铝钪（Al 1-xScxN）的Sc浓度高达x = 0.32的宽范围内从相同的材料源的第一次。此外，即使在x = 0.42时，也确定了质量密度和压电系数。采用反应脉冲直流磁控共溅射法在Si（001）衬底上制备了两组1 μ m厚的AlScN（0001）薄膜。一组薄膜被用来确定的a-和c-晶格参数和有效的相对介电系数ε（33，f），分别使用X射线衍射和电容测量。晶格参数，然后用于提取平均内部参数u，键长，键角，以及质量密度，作为Sc浓度的函数。进行密度泛函理论计算，以提供平衡晶格参数a，c和u，以及键角和键长的纤锌矿-AlN和层状六方-ScN。第二组膜用于制造具有从2到24 μ m的波长λ的表面声波（SAW）谐振器。SAW色散结合有限元建模拟合被用来提取弹性刚度以及压电系数。讨论了作为Sc浓度的函数的材料参数和晶体结构的变化的整体演变，以提供所观察到的行为的可能的解释。由AIP Publishing授权出版。
In this work, all electroacoustic material parameters, i.e., the elastic, piezoelectric, and dielectric coefficients, as well as the mass density, were determined experimentally for wurtzite aluminum scandium nitride (Al1-xScxN) for a wide range of Sc concentrations of up to x = 0.32 from the same material source for the first time. Additionally, the mass density and piezoelectric coefficient were determined even up to x = 0.42. Two sets of 1 mu m-thick AlScN(0001) thin films were deposited on Si(001) using reactive pulsed-DC magnetron cosputtering. One set of thin films was used to determine the a- and c-lattice parameters and the effective relative dielectric coefficient epsilon(33,f), using X-ray diffraction and capacitive measurements, respectively. Lattice parameters were then used to extract average internal parameter u, bond length, and bond angle, as well as mass density, as a function of Sc concentration. Density functional theory calculations were performed to provide the equilibrium lattice parameters a, c, and u, as well as the bond angle and the bond lengths for wurtzite-AlN and layered hexagonal-ScN. The second set of films was used to fabricate surface acoustic wave (SAW) resonators with wavelengths lambda from 2 up to 24 mu m. The SAW dispersion in conjunction with finite element modeling fitting was used to extract the elastic stiffness as well as the piezoelectric coefficients. The overall evolution of the material parameters and the change of the crystal structure as a function of Sc concentration is discussed in order to provide a possible explanation of the observed behavior. Published under license by AIP Publishing.