Interaction of acoustic waves in a piezoelectric-semiconductor resonant cavity with the charge carriers in the semiconductor layer can be directed toward amplification of the acoustic waves; such amplification scheme can be applied in building unilateral amplifiers, zero loss filters, oscillators, high detection range circuit-less wireless sensors, isolators, duplexers, circulators and other acoustic devices. An apparatus for acoustoelectric amplification is described. The apparatus includes a semiconductor layer and a thin piezoelectric layer bonded (or deposited) onto the semiconductor layer forming an acoustic cavity. Two or more tethers forming a current conduction path through the semiconductor layer and two or more access pads to silicon are positioned on two ends of the acoustic cavity and configured to inject a DC current in the semiconductor layer.

Devices and methods related to stack assembly. In some embodiments, a radio-frequency (RF) module can include a packaging substrate configured to receive a plurality of components, and an electro-acoustic device mounted on the packaging substrate. The RF module can further include a die having an integrated circuit and mounted over the electro-acoustic device to form a stack assembly. The electro-acoustic device can be, for example, a filter device such as a surface acoustic wave filter. The die can be, for example an amplifier die such as a low-noise amplifier implemented on a silicon die.

A surface acoustic wave (SAW) device comprises a substrate and composite electrodes. The composite electrodes comprise a metal layer and a graphene layer. The SAW device may be used to satisfy requirements for the fifth generation (5G) mobile communication.

A structure with a photodiode, an HEMT and an SAW device includes a photodiode and an HEMT. The photodiode includes a first electrode and a second electrode. The first electrode contacts a P-type III-V semiconductor layer. The second electrode contacts an N-type III-V semiconductor layer. The HEMT includes a P-type gate disposed on an active layer. A gate electrode is disposed on the P-type gate. Two source/drain electrodes are respectively disposed at two sides of the P-type gate. Schottky contact is between the first electrode and the P-type III-V semiconductor layer, and between the gate electrode and the P-type gate. Ohmic contact is between the second electrode and the first N-type III-V semiconductor layer, and between one of the two source/drain electrodes and the active layer and between the other one of two source/drain electrodes and the active layer.

Stack assembly having electro-acoustic device. In some embodiments, a radio-frequency (RF) module can include a packaging substrate configured to receive a plurality of components, and an electro-acoustic device mounted on the packaging substrate. The RF module can further include a die having an integrated circuit and mounted over the electro-acoustic device to form a stack assembly. The electro-acoustic device can be, for example, a filter device such as a surface acoustic wave filter. The die can be, for example an amplifier die such as a low-noise amplifier implemented on a silicon die.

An ultraviolet-ray (UV) sensor is disclosed. In one embodiment, the UV sensor includes a piezoelectric material, a sensing film arranged on the piezoelectric material and senses ultraviolet rays, an elastic wave input unit arranged on one end of the sensing film on the piezoelectric material and provides the sensing film with an elastic wave generated based on an electrical signal and an elastic wave output unit arranged on the other end of the sensing film on the piezoelectric material and senses a change in frequency of the electrical signal generated based on the provided elastic wave. The UV sensor improves sensitivity of the sensor by enabling the particles having large surface areas due to their characteristics to react with a larger amount of ultraviolet rays. the UV sensor can secure price competitiveness since the UV sensor measures a change in frequency of the elastic wave using zinc oxide (ZnO) nanoparticles.

A vibrator device includes a circuit element, which has a first terminal and is a quadrangle in plan view, a vibrator, which is disposed on an active surface and is a quadrangle in plan view, a base, on which the circuit element is disposed and which has a second terminal, and a wire which connects the first terminal and the second terminal together. In plan view of the circuit element, at least one side of the vibrator is disposed along a direction where the one side intersects each of two adjacent sides of the circuit element, and the vibrator does not overlap the first terminal.

An ultraviolet-ray (UV) sensor is disclosed. In one embodiment, the UV sensor includes a piezoelectric material, a sensing film arranged on the piezoelectric material and senses ultraviolet rays, an elastic wave input unit arranged on one end of the sensing film on the piezoelectric material and provides the sensing film with an elastic wave generated based on an electrical signal and an elastic wave output unit arranged on the other end of the sensing film on the piezoelectric material and senses a change in frequency of the electrical signal generated based on the provided elastic wave. The UV sensor improves sensitivity of the sensor by enabling the particles having large surface areas due to their characteristics to react with a larger amount of ultraviolet rays. the UV sensor can secure price competitiveness since the UV sensor measures a change in frequency of the elastic wave using zinc oxide (ZnO) nanoparticles.

A surface acoustic wave resonator device comprises a substrate supporting: a gateable, electrically conducting layer; an interdigital transducer (IDT); a reflector grating that comprises a plurality of electrically separated fingers; a main ohmic contact; and a gate element. The IDT is configured to be connectable to a ground. The conducting layer is configured to be connectable to the ground via the main ohmic contact, while each of said fingers is electrically connected to a lateral side of the conducting layer. This defines a gateable channel, which extends from the fingers to the ground via the conducting layer and the main ohmic contact. The gate element is electrically insulated from the conducting layer. The gate element is configured to allow an electrical impedance of the gateable channel to be continuously tuned by applying a voltage bias to this gate element with respect to the ground, in operation of the device.

Due to strong needs to reduce the dimensions and the cost of the RF filters and to reduce the number of filters required in an mobile handsets and wireless system covering numbers of operation bands, tunable RF filters which can cover as many bands or frequency ranges as possible are needed so that the number of filters can be reduced in the mobile handsets and wireless systems. This invention provides tunable surface acoustic wave resonators and filters utilizing semiconducting piezoelectric layers having embedded or elevated electrode doped regions. Both metallization ratio and loading mass are changed by varying a DC biasing voltage to effect a change in the resonant frequency of the tunable SAW devices.