In a piezoelectric device, electrode layers are spaced apart from each other in the direction of the normal thereto. A first piezoelectric layer is interposed between two electrode layers of electrode layers in the direction of the normal. A second piezoelectric layer is provided on an opposite side of the first piezoelectric layer from a base portion. The second piezoelectric layer is interposed between two electrode layers of the electrode layers in the direction of the normal. The half-width of a rocking curve measured by X-ray diffraction for a lattice plane of the first piezoelectric layer substantially parallel to a first main surface is smaller than a half-width for the second piezoelectric layer. The piezoelectric constant of a material defining the first piezoelectric layer is smaller than the piezoelectric constant of a material defining the second piezoelectric layer.

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.

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.

Doped-aluminum nitride (doped-AlN) films and methods of manufacturing doped-AlN films are disclosed. Some methods comprise forming alternating pinning layers and doped-AlN layers including a dopant selected from the group consisting of Sc, Y, Hf, Mg, Zr and Cr, wherein the pinning layers pin the doped-AlN layers to a c-axis orientation. Some methods include forming a conducting layer including a material selected from the group consisting of Mo, Pt, Ta, Ru, LaNiO.sub.3 and SrRuO.sub.3. Some methods include forming a thermal oxide layer having silicon oxide on a silicon substrate. Piezoelectric devices comprising the doped-AlN film are also disclosed.

There is provided a piezoelectric stack, including: a substrate; an output-side bottom electrode film on the substrate; an output-side piezoelectric film, being an oxide film, on the output-side bottom electrode film; an output-side top electrode film on the output-side piezoelectric film; an input-side bottom electrode film on the substrate; an input-side piezoelectric film, being a nitride film, on the input-side bottom electrode film; an input-side top electrode film on the input-side piezoelectric film; and an ultrasonic output part and ultrasonic input part placed in such a manner as not overlapping each other when viewed from a top surface of the substrate, the ultrasonic output part comprising a stacked part of the output-side bottom electrode film, the output-side piezoelectric film, and the output-side top electrode film, the ultrasonic input part comprising a stacked part of the input-side bottom electrode film, the input-side piezoelectric film, and the input-side top electrode film.

There is provided a piezoelectric laminate has, on a substrate in the following order, a lower electrode layer and a piezoelectric film containing a perovskite-type oxide as a main component. The piezoelectric film has an oxygen-deficient region in a region in contact with the lower electrode layer. In a case where an average value of oxygen amounts in a region centrally located among three regions obtained by dividing the piezoelectric film into three equal parts in a thickness direction is denoted as a first average oxygen amount, and an average value of oxygen amounts in the oxygen-deficient region is denoted as a second average oxygen amount, a ratio R of the second average oxygen amount to the first average oxygen amount is less than 0.97. A thickness of the oxygen-deficient region is 120 nm or more and is ⅓ or less of a thickness of the entire piezoelectric film.

A piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film comprising an alkali niobium oxide of a perovskite structure represented by a composition formula of (K.sub.1-xNa.sub.x)NbO.sub.3 (0<x<1), wherein an average light transmittance through the piezoelectric film in a wavelength region of visible light and near-infrared ray is 65% or more.

A piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film comprising an alkali niobium oxide of a perovskite structure represented by a composition formula of (K.sub.1-xNa.sub.x)NbO.sub.3 (0<x<1), wherein an average light transmittance through the piezoelectric film in a wavelength region of visible light and near-infrared ray is 65% or more.

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.

Piezoelectric transducers are provided. The piezoelectric transducer includes a first piezoelectric layer, a second piezoelectric layer disposed on at least a portion of the first piezoelectric layer, and a middle electrode layer disposed between the first and second piezoelectric layers, where the middle electrode layer includes an inner region and an outer region spaced apart from the inner region. Methods of making the piezoelectric transducers are also provided. The piezoelectric transducers and methods find use in a variety of applications, including devices, such as electronics devices having one or more (e.g., an array) of the piezoelectric transducers.