Patent ID: 7229662

Claim:
A method of forming a heterolayered thin film, comprising: (a) forming a first precursor layer capable of being crystallized into a rhombohedral structure of a first ferroelectric/piezoelectric material; (b) baking said first precursor layer without crystallizing said first precursor layer; (c) forming a second precursor layer capable of being crystallized into a tetragonal structure of a second ferroelectric/piezoelectric material on said first precursor layer; (d) baking said second precursor layer at a temperature for a period of time sufficient to crystallize said second precursor layer without crystallizing said first precursor layer; (e) after said second precursor layer is crystallized, annealing said first and second precursor layers, thus crystallizing said first precursor layer and forming a crystallized thin film that comprises a first ferroelectric/piezoelectric layer having a rhombohedral crystal structure, and a second ferroelectric/piezoelectric layer on said first ferroelectric/piezoelectric layer and having a tetragonal crystal structure, said first and second ferroelectric/piezoelectric layers having a (100) preferred orientation with α-axis normal to a surface of said thin film.