Extraction of kt2 of piezoelectric film/substrate structure by conversion loss derived by electromagnetic signal including no acoustic losses

Electromechanical coupling coefficient (k
_t
²
) is an important parameter for determining the performances of RF BAW filters. According to the IEEE standard, the resonance-antiresonance method for a self-standing film structure is recommended to determine k
_t
²
of the piezoelectric film. It is convenient and cost-effective to determine the k
_t
²
from the film/wafer structure or epitaxial wafers. However, k
_t
²
is underestimated due to the acoustic losses in the substrate in the conventional conversion loss method, which is powerful tool to extract the k
_t
²
from HBAR. In this study, we introduce the conversion loss using electromagnetic signal including no acoustic losses.