Apparatus for transducing a surface acoustic wave
An apparatus including a piezoelectric substrate configured to propagate a surface acoustic wave; and a transducer, coupled to the piezoelectric substrate, including at least one graphene electrode configured to transduce a propagating surface acoustic wave to an electrical signal.
1. An apparatus comprising:
a piezoelectric substrate configured to propagate a surface acoustic wave;
a transducer, coupled to the piezoelectric substrate, comprising at least one graphene electrode configured to transduce a propagating surface acoustic wave to an electrical signal; and
a ground reference potential node configured to provide a ground reference potential that is independent of the surface acoustic wave;
wherein the at least one graphene electrode comprises a two-dimensional graphene ribbon monolayer configured to be a semiconductor with zero band gap;
wherein the transducer is configured to transduce a propagating surface acoustic wave to an output direct current electrical signal;
wherein the propagating surface acoustic wave has a frequency of greater than 1 THz; and
wherein the piezoelectric substrate and the at least one graphene electrode are coupled to form a channel having a variable transconductance that provides an output signal that develops an electric voltage relative to the ground reference potential node.
2. An apparatus as claimed in claim 1 , wherein the graphene electrode is a two-dimensional electrode having an electric field dependent conductivity.
3. An apparatus as claimed in claim 1 , wherein the graphene electrode is coupled to the piezoelectric substrate and has a conductivity that is dependent upon a coupled electric field such that a varying electric field at the piezoelectric substrate, caused by a propagating surface acoustic wave, is coupled to the graphene electrode to vary the conductivity of the graphene electrode.
4. An apparatus as claimed in claim 3 , wherein the varying electric field at the piezoelectric substrate is within a range within which the change in conductivity of the graphene with electric field is monotonic.
5. An apparatus as claimed in claim 1 , wherein the transducer comprises a plurality of parallel graphene electrodes each configured to transduce a propagating surface acoustic wave to an electrical signal.
6. An apparatus as claimed in claim 5 , wherein the plurality of parallel graphene electrodes extend in a second direction that is orthogonal to a first direction in which the surface acoustic wave propagates.
7. An apparatus as claimed in claim 5 , wherein the plurality of parallel graphene electrodes are electrically interconnected.
8. An apparatus as claimed in claim 7 , wherein the plurality of parallel graphene electrodes are electrically interconnected in electrical parallel to provide the output signal that develops the electric voltage.
9. An apparatus as claimed in claim 7 , wherein the plurality of parallel graphene electrodes are electrically interconnected in electrical series to output an electric current.
10. An apparatus as claimed in claim 1 wherein the transducer is configured to transduce surface acoustic waves having a maximum wavelength and wherein the graphene electrode has a width in a direction of propagation of the surface acoustic waves greater than or equal to N times the maximum wavelength, where N is greater than or equal to 1.
11. An apparatus as claimed in claim 10 wherein N is greater than or equal to 2.
12. An apparatus as claimed in claim 1 , wherein the transducer is configured to transduce, at room temperature, a propagating surface acoustic wave to an electrical signal.
13. An apparatus as claimed in claim 1 , configured as a module.
14. An apparatus as claimed in claim 1 , comprised within an analog signal processor, a high-frequency rectifier, an energy harvester, a demodulator, or a receiver.
15. An apparatus comprising:
a piezoelectric substrate configured to propagate a surface acoustic wave;
a transducer, coupled to the piezoelectric substrate, comprising at least one electrode configured to transduce a propagating surface acoustic wave to an output direct current electrical signal; and
a ground potential reference node configured to provide a ground potential reference that is independent of the surface acoustic wave, wherein the electrode is coupled to the piezoelectric substrate and has a conductivity that is dependent upon a coupled electric field such that a varying electric field at the piezoelectric substrate, caused by a propagating surface acoustic wave, is coupled to the electrode and varies the conductivity of the electrode, and wherein the electrode comprises a two-dimensional graphene ribbon monolayer configured to be a semiconductor with zero band gap;
wherein the propagating surface acoustic wave has a frequency of greater than 1 THz; and
wherein the piezoelectric substrate and the at least one electrode are coupled to form a channel having a variable transconductance that provides an output signal that develops an electric voltage relative to the ground potential reference node.
16. An apparatus comprising:
a piezoelectric substrate configured to propagate a surface acoustic wave;
a transducer, coupled to the piezoelectric substrate, and configured to transduce a propagating surface acoustic wave to an output direct current electrical potential, the transducer comprising an electrode comprising a two-dimensional graphene ribbon monolayer configured to be a semiconductor with zero band gap; and
a ground potential node configured to provide a ground potential that is independent of the surface acoustic wave;
wherein the propagating surface acoustic wave has a frequency of greater than 1 THz; and
wherein the piezoelectric substrate and the electrode are coupled to form a channel having a variable transconductance that provides an output signal that develops an electric voltage relative to the ground potential node.
17. An apparatus comprising:
a piezoelectric substrate configured to propagate a surface acoustic wave; and
a transducer, coupled to the piezoelectric substrate, and configured to transduce a propagating surface acoustic wave to an output direct current electrical potential, the transducer comprising an electrode comprising a two-dimensional graphene ribbon monolayer configured to be a semiconductor with zero band gap;
wherein the propagating surface acoustic wave has a frequency of greater than 1 THz; and
wherein the piezoelectric substrate and the electrode are coupled to form a channel having a variable transconductance that provides an output signal that develops an electric voltage relative to a ground potential node.