Hybrid semiconductor-piezoacoustic radiofrequency device
| DWPI Title: Amplifying radio-frequency (RF) device, has piezoelectric film having thickness less than wavelength of acoustic wave, and semiconductor amplifier layer which is distant from piezoelectric film by less than wavelength of acoustic wave |
| Abstract: An amplifying radiofrequency device includes a piezoelectric film and a semiconductor amplifier layer. The piezoelectric film is conformed as an acoustic waveguide. The piezoelectric film has a principal acoustic propagation direction parallel to the principal conduction direction of the amplifier layer. Interdigitated transducers are positioned on the piezoelectric film to respectively launch an acoustic wave in response to an input RF signal, and transduce the acoustic wave back to an output RF signal. There is a distance of less than the acoustic wavelength between the semiconductor amplifier layer and the piezoelectric film. The piezoelectric film has a thickness of less than the acoustic wavelength. According to a method for making such a device, a stack of III-V layers is epitaxially grown on a III-V substrate, wherein the stack comprises a first etch stop layer, a second etch stop layer, an amplifier layer, and a contact layer. The stack is bonded to a lithium niobate film. The III-V substrate is removed by etching down to the first etch stop layer. Deposition windows are opened by etching from the first etch stop layer down to the contact layer. Metal contact electrodes are deposited in the deposition windows. |
| Use: Amplifying radio-frequency (RF) device. |
| Advantage: The density of unwanted modes is reduced by reducing the thickness of the piezoelectric membrane to much less than an acoustic wavelength. The mode density is further reduced by using focusing IDTs to couple RF power into an acoustic waveguide that is not only sub-wavelength in thickness, but also sub-wavelength in width. |
| Novelty: The amplifying RF device includes a piezoelectric film (14) conformed as an acoustic waveguide (16) having a principal acoustic propagation direction and a semiconductor amplifier layer positioned near the piezoelectric film and having a principle conduction direction parallel to the principal acoustic propagation direction. An input interdigitated transducer (IDT) is positioned on the piezoelectric film and conformed to launch an acoustic wave (14) into the piezoelectric film in response to an input RF signal. An output interdigitated transducer (IDT) is positioned on the piezoelectric film and conformed to intercept the launched acoustic wave and convert it to an output RF signal. The semiconductor amplifier layer is distant from the piezoelectric film by less than the wavelength of the acoustic wave. The piezoelectric film has a thickness of less than the wavelength of the acoustic wave. |
| Filed: 9/28/2017 |
| Application Number: US15718817A |
| Tech ID: SD 13698.1 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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