Abstract: A bulk-acoustic wave resonator comprises a substrate, a resonant portion comprising a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on the substrate, and further comprising a center portion and an extension portion that is disposed along a periphery of the center portion, and an insertion layer that is disposed in the extension portion between the first electrode and the piezoelectric layer, and the insertion layer is formed of an aluminum alloy containing scandium (Sc).

Abstract: A bulk-acoustic wave resonator comprises a substrate, a resonant portion comprising a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on the substrate, and further comprising a center portion and an extension portion that is disposed along a periphery of the center portion, and an insertion layer that is disposed in the extension portion between the first electrode and the piezoelectric layer, and the insertion layer is formed of an aluminum alloy containing scandium (Sc).

Abstract: A bulk-acoustic wave resonator includes a substrate, a first electrode disposed on the substrate, a piezoelectric layer, of which at least a portion is disposed on the first electrode, a second electrode disposed on the piezoelectric layer, and a passivation layer disposed to cover the first electrode and the second electrode. Either one or both of the first electrode and the second electrode includes an aluminum alloy layer. Either one or both of the piezoelectric layer and the passivation layer has aluminum nitride, or aluminum nitride added with a doping material, having a ratio of an out-of-plane lattice constant “c” to an in-plane lattice constant “a” (c/a) of less than 1.58.

Abstract: A bulk-acoustic wave resonator includes: a substrate; a seed layer disposed on the substrate, and having a hexagonal crystal structure; a bottom electrode disposed on the seed layer; a piezoelectric layer at least partially disposed on the bottom electrode; and a top electrode disposed on the piezoelectric layer, wherein either one or both of the bottom electrode and the top electrode includes a scandium (Sc)-containing aluminum alloy layer.

Abstract: A film bulk acoustic resonator includes: a first electrode disposed on a substrate; a piezoelectric body disposed on the first electrode and including AlN to which a dopant is added; and a second electrode disposed on the piezoelectric body and facing the first electrode such that the piezoelectric body is interposed between the second electrode and the first electrode, wherein the dopant includes either one of 0.1 to 24 at % of Ta and 0.1 to 23 at % of Nb.

Abstract: A bulk-acoustic wave resonator may include: a substrate; a resonance portion; a first electrode disposed on the substrate; a piezoelectric layer disposed on the first electrode in the resonance portion; a second electrode disposed on the piezoelectric portion in the resonance portion; and a seed layer disposed in a lower portion of the first electrode. The seed layer may be formed of titanium (Ti) having a hexagonal close packed (HCP) structure, or an alloy of Ti having the HCP structure. The seed layer may have a thickness greater than or equal to 300 ? and less than or equal to 1000 ?, or may be thinner than the first electrode.

Abstract: A bulk acoustic wave resonator includes: a first electrode; a piezoelectric layer disposed on at least a portion of the first electrode; and a second electrode disposed on the piezoelectric layer. The piezoelectric layer contains a dopant, and a value of [a thickness (nm) of the piezoelectric layer×a concentration (at %) of the dopant]/100 is less than or equal to 80.

Abstract: An acoustic resonator includes a membrane layer disposed on an insulating layer; a cavity formed by the insulating layer and the membrane layer and having a hydrophobic layer disposed on at least one of a portion of an upper surface of the cavity and a portion of a lower surface of the cavity; and a resonating portion disposed on the cavity and having a second electrode on a piezoelectric layer on a first electrode.

Abstract: A bulk-acoustic wave resonator is provided. The bulk-acoustic wave resonator comprises a substrate comprising an external connection electrode; a connection layer connected to the external connection electrode and disposed on the substrate; a first electrode disposed to cover at least a portion of the connection layer; a piezoelectric layer disposed to cover at least a portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The connection layer may be disposed to surround a cavity and may be connected to the first electrode and the second electrode.

Abstract: An acoustic resonator includes a substrate, a center portion, an extending portion, and a barrier layer. A first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on the substrate in the central portion. The extending portion is configured to extend from the center portion, and includes an insertion layer disposed below the piezoelectric layer. The barrier layer is disposed between the first electrode and the piezoelectric layer.

Abstract: A bulk acoustic wave resonator includes a substrate, a seed layer disposed on the substrate, a first electrode disposed on the seed layer and including an aluminum alloy layer containing scandium (Sc), a piezoelectric layer disposed on the first electrode and including a layer having a cation (Al) polarity, and a second electrode disposed on the piezoelectric layer.

Abstract: A bulk acoustic wave resonator includes: a first electrode; a piezoelectric layer disposed on at least a portion of the first electrode; and a second electrode disposed on the piezoelectric layer. The piezoelectric layer contains a dopant, and a value of [a thickness (nm) of the piezoelectric layer x a concentration (at %) of the dopant]/100 is less than or equal to 80.

Abstract: A fine dust concentration sensor includes a bulk acoustic resonator and a cap including an upper portion with holes therein and a lateral portion connected to the upper portion to accommodate the bulk acoustic resonator. An upper surface of the upper portion of the cap is coated with a hydrophobic material.

Abstract: A bulk-acoustic wave resonator may include: a substrate; a resonance portion; a first electrode disposed on the substrate; a piezoelectric layer disposed on the first electrode in the resonance portion; a second electrode disposed on the piezoelectric portion in the resonance portion; and a seed layer disposed in a lower portion of the first electrode. The seed layer may be formed of titanium (Ti) having a hexagonal close packed (HCP) structure, or an alloy of Ti having the HCP structure. The seed layer may have a thickness greater than or equal to 300 ? and less than or equal to 1000 ?, or may be thinner than the first electrode.

Abstract: A bulk-acoustic wave resonator is provided. The bulk-acoustic wave resonator comprises a substrate comprising an external connection electrode; a connection layer connected to the external connection electrode and disposed on the substrate; a first electrode disposed to cover at least a portion of the connection layer; a piezoelectric layer disposed to cover at least a portion of the first electrode; and a second electrode disposed to cover at least a portion of the piezoelectric layer. The connection layer may be disposed to surround a cavity and may be connected to the first electrode and the second electrode.

Abstract: A bulk acoustic wave resonator includes: a substrate; a first electrode disposed on the substrate; a piezoelectric layer at least partially disposed on the first electrode; and a second electrode disposed on the piezoelectric layer; wherein the first electrode includes an aluminum alloy layer containing scandium (Sc), and has a surface roughness of 2.4 nm or less, based on an arithmetic mean roughness.

Abstract: A bulk acoustic wave resonator includes: a substrate; a lower electrode disposed on the substrate; a piezoelectric layer at least partially disposed on the lower electrode; and an upper electrode disposed on the piezoelectric layer, wherein either one or both of the lower electrode and the upper electrode includes a layer of aluminum alloy including scandium (Sc).

Abstract: A bulk-acoustic wave resonator comprises a substrate, a resonant portion comprising a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on the substrate, and further comprising a center portion and an extension portion that is disposed along a periphery of the center portion, and an insertion layer that is disposed in the extension portion between the first electrode and the piezoelectric layer, and the insertion layer is formed of an aluminum alloy containing scandium (Sc).

Abstract: A bulk acoustic wave resonator includes a substrate, a seed layer disposed on the substrate, a first electrode disposed on the seed layer and including an aluminum alloy layer containing scandium (Sc), a piezoelectric layer disposed on the first electrode and including a layer having a cation (Al) polarity, and a second electrode disposed on the piezoelectric layer.

Abstract: A bulk acoustic wave resonator includes a substrate protective layer disposed on a top surface of a substrate, a cavity defined by a membrane layer and the substrate, and a resonating part disposed on the membrane layer. The membrane layer includes a first layer and a second layer, the second layer having the same material as the first layer and having a density greater than that of the first layer.