Piezoelectric element

Patent Pending PROBLEM TO BE SOLVED: To provide an optical branching filter comprising a piezoelectric element of a cantilever beam structure formed with zinc oxide (ZnO). ; SOLUTION: A Ge layer 120 is used as a sacrificing layer, oxygenated water is used as an etching solution to make a cantilever beam structure (a, b). An n type ZnO layer (low resistance layer) 140- a ZnO layer (piezoelectric conductive film) 150- an n type ZnO layer (low resistance layer) 160 is formed as a piezoelectric element (c, d).