Piezoelectric device

A piezoelectric device comprising:

• a base portion;
• and
• a membrane portion indirectly supported by the base portion, positioned above the base portion, and including a plurality of layers;
• wherein
• the membrane portion does not overlap the base portion and includes a single-crystal piezoelectric layer including a first surface facing upward and a second surface on a side opposite to the first surface in a vertical direction, an upper electrode layer on the first surface, and a lower electrode layer on the second surface so as to face at least a portion of the upper electrode layer sandwiching the single-crystal piezoelectric layer in between;
• the single-crystal piezoelectric layer is made of lithium tantalate or lithium niobate and includes a plurality of piezoelectric body cleavage directions extending along a boundary line between a cleavage plane occurring when the single-crystal piezoelectric layer is cleaved and the first surface;
• at least one of the base portion and the membrane portion includes a single-crystal silicon layer;
• the single-crystal silicon layer includes an upper surface facing upward and a plurality of silicon cleavage directions extending along a boundary line between a cleavage plane occurring when the single-crystal silicon layer is cleaved and the upper surface;
• and
• at least one direction of the plurality of piezoelectric body cleavage directions is non-parallel to each of the plurality of silicon cleavage directions.