Integration of semiconductor membranes with piezoelectric substrates
Piezoelectrically actuated devices constructed from thin semiconductor membranes bonded directly to piezoelectric substrates are provided. Methods for fabricating these devices are also provided. The bonding of the semiconductor to the piezoelectric material does not require the use of any intermediate layers, such as bonding agents.
1. A piezoelectric transducer comprising:
a piezoelectric substrate consisting of a piezoelectric material and having a surface with a surface roughness of no greater than 100 nm RMS;
a semiconductor membrane having a thickness of 5 μm or less bonded directly to the piezoelectric material at the surface, such that no other material is applied or inserted between the piezoelectric material and the semiconductor membrane; and
a set of electrodes in electrical communication with the piezoelectric substrate and configured to apply an electric signal to the piezoelectric substrate.
2. The transducer of claim 1 , wherein the surface has a surface roughness of no greater than 50 nm RMS.
3. The transducer of claim 1 , wherein the semiconductor membrane has a thickness of no greater than 500 nm.
4. The transducer of claim 3 , wherein the semiconductor membrane has a thickness of no greater than 100 nm.
5. The transducer of claim 1 , wherein the semiconductor membrane comprises a Group IV semiconductor.
6. The transducer of claim 5 , wherein the semiconductor membrane is a silicon membrane.
7. The transducer of claim 1 , wherein the piezoelectric material is doped or undoped lead zirconium titanate.
8. The transducer of claim 7 , wherein the semiconductor membrane is a silicon membrane.
9. The transducer of claim 1 further comprising an external voltage source configured to apply a voltage across the piezoelectric substrate.
10. The transducer of claim 1 further comprising one or more electronic devices integrated into the semiconductor membrane.
11. The transducer of claim 1 , wherein an aperture is defined in the piezoelectric substrate and a portion of the semiconductor membrane is suspended over the aperture.
12. The transducer of claim 11 , wherein one or more holes are defined in the portion of the semiconductor membrane that is suspended over the aperture.
13. The transducer of claim 1 , wherein the piezoelectric material is lead zirconium titanate lithium niobate, lead magnesium niobate-lead titanate (PMN-PT), lead zinc niobate lead titanate (PZN-PT), LiNbO 3 , gallium phosphate, quartz, or tourmaline.