A multilayer structure and a piezoelectric device using the same, which have satisfactory crystal orientation even in the submicron region of the thickness of a piezoelectric layer, are provided. The multilayer structure includes a first wurtzite thin film, a first hexagonal metal layer, a first electrode layer, a second hexagonal metal layer, and a second wurtzite thin film stacked in this order. The first electrode layer is formed of a metallic material having an acoustic impedance higher than that of the second wurtzite thin film.

Disclosed is a method of manufacturing an epitaxy oxide thin film of enhanced crystalline quality, and an epitaxy oxide thin film manufactured thereby according to the present invention. With respect to the manufacturing method of the epitaxy oxide thin film, which epitaxially grows an orientation film with an oxide capable of being oriented to (001), (110), and (111) on a single crystal Si substrate, because time required for raising a temperature of the orientation film up to an annealing temperature at room temperature is extremely minimized, thermal stress arising from the large difference in thermal expansion coefficients between the substrate and the orientation film is controlled, so crystalline quality of the epitaxy oxide thin film can be enhanced. Moreover, various epitaxial functional oxides are integrated into the thin film of enhanced crystalline quality so that a novel electronic device can be embodied.

A piezoelectric device includes a base member, a first conductive film arranged above the base member in contact with an upper surface of the base member, a piezoelectric film arranged above the first conductive film in contact with an upper surface of the first conductive film, a second conductive film arranged on the piezoelectric film, and an insulating portion provided inside a trench penetrating through the piezoelectric film and the first conductive film. The insulating portion has a higher electrical resistivity than the piezoelectric film.

A piezoelectric element includes, on a base, an underlying layer for controlling crystallinity of a piezoelectric layer, and the piezoelectric layer. The piezoelectric layer includes a crystal with an ABO.sub.3-type structure having at least Pb at A sites. In the underlying layer, an interface-with-the-base side is configured including at least Pb and another substance with a different composition rate from that of the piezoelectric layer at the A sites, and a substance with a different composition ratio from that of the piezoelectric layer at B sites. In a layer above the interface-with-the-base side in the underlying layer, the composition rate of the other substance included at the A sites of the underlying layer progressively changes and also the composition ratio of the substance included at the B sites progressively changes, from the interface-with-the-base side toward the interface-with-the-piezoelectric-layer side to approach the composition of the piezoelectric layer.

Disclosed is a method of manufacturing a piezoelectric substrate, the method including: forming an intermediate layer of Ti and a lower electrode of Pt oriented in a (111) axis direction on a substrate without heating the substrate; applying a coating liquid for forming an orientation control layer made of lead titanate onto the lower electrode; drying the coating liquid at a predetermined temperature to form an orientation control layer precursor made of lead titanate; applying a coating liquid for forming a piezoelectric thin film made of lead zirconate titanate; drying the coating liquid at a predetermined temperature to form a piezoelectric precursor made of a lead zirconate titanate precursor; and collectively firing the orientation control layer precursor and the piezoelectric precursor to crystallize both the precursors, to thereby form a piezoelectric thin film made of lead zirconate titanate preferentially oriented in a (110) plane.

A layered solid element includes a ferroelectric layer of a crystalline material Li.sub.1−x(Nb.sub.1−yTa.sub.y).sub.1+xO.sub.3+2x−z which has X- or 33° Y-orientation with respect to a substrate of the layered solid element. The ferroelectric layer is grown epitaxially from a buffer layer having of one of the chemical formulae L.sub.kNi.sub.rO.sub.1.5.Math.(k+r)+w or L.sub.n+1Ni.sub.nO.sub.3n+1+δ, where L is a lanthanide element. Such layered solid element may form a thin-film bulk acoustic resonator and be useful for integrated electronic circuits such as RF-filters, or guided optical devices such as integrated optical modulators.

A layered solid element includes a ferroelectric layer of a crystalline material Li.sub.1−x(Nb.sub.1−yTa.sub.y).sub.1+xO.sub.3+2x−z which has X- or 33° Y-orientation with respect to a substrate of the layered solid element. The ferroelectric layer is grown epitaxially from a buffer layer having of one of the chemical formulae L.sub.kNi.sub.rO.sub.1.5.Math.(k+r)+w or L.sub.n+1Ni.sub.nO.sub.3n+1+δ, where L is a lanthanide element. Such layered solid element may form a thin-film bulk acoustic resonator and be useful for integrated electronic circuits such as RF-filters, or guided optical devices such as integrated optical modulators.

A stacked film is a stacked film including an oxide film, and a metal film provided on the oxide film, in which the oxide film includes a ZrO.sub.2 film of which a main surface is a (001) plane, the metal film includes a Pt film or a Pd film that has a single orientation and of which a main surface is a (001) plane, and a [100] axis of the ZrO.sub.2 film and a [100] axis of the metal film are parallel to an interface between the oxide film and the metal film, and the axes of both are parallel to each other.

A method for forming a lithium niobate- or lithium tantalum-based (LN/LT) layer includes providing a silicon-based substrate, forming nucleation layer on the substrate, and forming the LN/LT layer by epitaxy on the nucleation layer. The nucleation layer is chosen based upon a III-N material. The nucleation layer may be used in a surface acoustic wave device.

Provided is an ultrasonic sensor including a piezoelectric elements arranged along a first direction and a second direction on a vibration plate, an insulation layer, and conductive lines. Each piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode. The first electrode is partially removed in a regions between the piezoelectric elements. The second electrode is a separate electrode provided for each piezoelectric element. The insulation layer covers the second electrodes and has holes through which portions at opposite ends of the second electrodes along the first direction are partially exposed. Each conductive line is provided between adjacent ones of the second electrodes along the first direction and electrically connects, via the holes, the adjacent ones of the second electrodes.