Experimental and theoretical investigation of kt2and mechanical quality factor Qm in YbAlN films using DFT

In the RF filter, both high k
_t
²
and high Q
_m
are required. Now AlN films are used in the BAW filters because of high Q
_m
, but AlN has low k
_t
²
. Our group previously found the enhancement of k
_t
²
in YbAlN films [1] and reported theoretical prediction of k
₃₃
²
in Yb
_x
Al
_1-x
N for the range of x=0 to 11 % [2]. In this study, we report the theoretical prediction of characteristic in Yb
_x
Al
_1-x
N for the range of x=16.7 to 33% Furthermore, we estimate the experimental mechanical quality factor Q
_m
of the YbAlN thin film. As a result, when Yb atomic concentration is 33%, the k
₃₃
²
of YbAlN is predicted to be 22%. It is approximately 3 times that of pure AlN. It was also confirmed that the Q
_m
decreased with doping Yb.