Piezoelectric thin-film multilayer body
A piezoelectric thin-film multilayer body includes a substrate, an adhesive layer on the substrate, a lower electrode layer on the adhesive layer, and a lead-free piezoelectric thin-film layer on the lower electrode layer. The lead-free piezoelectric thin-film layer is composed of lithium potassium sodium niobate (composition formula (Na x K y Li z )NbO 3 , 0<x<1, 0<y<1, 0≦z≦1, x+y+z=1). The maximum height Rz of a roughness of an adhesive-layer-facing surface of the substrate is 2 nm or less. The adhesive layer is composed of a non-crystalline oxide of a Group 4 element or a non-crystalline oxide of a Group 5 element. The adhesive layer has a thickness of 1 nm or more and 2 nm or less and is equal to or more than the maximum height Rz of the roughness of the surface of the substrate.
1. A piezoelectric thin-film multilayer body comprising:
a substrate;
an adhesive layer on the substrate;
a lower electrode layer on the adhesive layer; and
a lead-free piezoelectric thin-film layer on the lower electrode layer,
wherein the lead-free piezoelectric thin-film layer is composed of lithium potassium sodium niobate (composition formula (Na x K y Li z )NbO 3 , 0<x<1, 0<y<1, 0≦z≦1, x+y+z=1),
wherein a maximum height Rz of a roughness of an adhesive-layer-facing surface of the substrate is 2 nm or less,
wherein the adhesive layer is composed of a non-crystalline oxide of a Group 4 element or a non-crystalline oxide of a Group 5 element, and
wherein the adhesive layer has a thickness of 1 nm or more and 2 nm or less and is equal to or more than the maximum height Rz of the roughness of the surface of the substrate.
2. The piezoelectric thin-film multilayer body according to claim 1 ,
wherein an arithmetic average roughness Ra of the roughness of the surface of the substrate is 0.18 nm or less.
3. The piezoelectric thin-film multilayer body according to claim 1 ,
wherein the lower electrode layer has a (111) preferred orientation.
4. The piezoelectric thin-film multilayer body according to claim 1 ,
wherein the Group 4 element constituting the adhesive layer is titanium (Ti).
5. The piezoelectric thin-film multilayer body according to claim 1 ,
wherein the lower electrode layer is composed of platinum (Pt) or a platinum (Pt) alloy.
6. The piezoelectric thin-film multilayer body according to claim 1 ,
wherein the substrate is any one selected from a silicon (Si) substrate, a silicon-on-insulator (SOI) substrate, a germanium (Ge) substrate, a magnesium oxide (MgO) substrate, a zinc oxide (ZnO) substrate, a strontium titanate (SrTiO 3 ) substrate, a strontium ruthenate (SrRuO 3 ) substrate, a sapphire (Al 2 O 3 ) substrate, a gallium arsenide (GaAs) substrate, a gallium nitride (GaN) substrate, a glass substrate, and a quartz glass substrate.
7. A piezoelectric thin-film device comprising the piezoelectric thin-film multilayer body according to claim 1 .
8. A piezoelectric thin-film multilayer body comprising:
a substrate;
an adhesive layer on the substrate;
a lower electrode layer on the adhesive layer; and
a lead-free piezoelectric thin-film layer on the lower electrode layer,
wherein the lead-free piezoelectric thin-film layer is composed of a ferroelectric having a perovskite structure,
wherein a maximum height Rz of a roughness of an adhesive-layer-facing surface of the substrate is 2 nm or less,
wherein the adhesive layer is composed of a non-crystalline oxide of a Group 4 element or a non-crystalline oxide of a Group 5 element, and
wherein the adhesive layer has a thickness of 1 nm or more and 2 nm or less and is equal to or more than the maximum height Rz of the roughness of the surface of the substrate.
9. The piezoelectric thin-film multilayer body according to claim 8 ,
wherein arithmetic average roughness Ra of the roughness of the surface of the substrate is 0.18 nm or less.