Integrated tunable surface acoustic wave technology and sensors provided thereby
First Claim
1. A SAW sensor comprising:
- an R-plane sapphire substrate;
a first and second layers of piezoelectric member comprised of zinc oxide disposed on said substrate;
a quantum well structure comprised of zinc oxide and magnesium zinc oxide heterostructure disposed on said first layer of said piezoelectric member;
input and output IDTs disposed on said second layer of said piezoelectric member;
a metal electrode disposed on said heterostructure and on a SAW path of said piezoelectric member;
a sensing coating disposed on top of said SAW path of the piezoelectric member.
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Abstract
The present invention provides a ZnO based tunable surface acoustic wave (SAW), preferably monolithically integrated tunable SAW (MITSAW) device. The MITSAW comprises a ZnO/MgxZn1−xO quantum well structure and piezoelectric ZnO thin film epitaxially grown on R-plane sapphire ((01{overscore (1)}2)Al2O3) substrate using MOCVD. R-plane sapphire provides in-plane anisotropy in the ZnO layer as the c-axis of ZnO lies in the growth plane. A two-dimensional electron gas (2DEG) is placed in the delay path of the SAW device and interacts with the lateral electric field resulting in ohmic loss which attenuates and slows the surface acoustic wave. This mechanism is used to tune the acoustic velocity. The high coupling coefficients offered by the ZnO/R-(Al2O3) system allows large velocity tuning. ZnO based MITSAW is used for chemical and biochemical sensors, offers excellent manufacturability, high yield and low cost. Such SAW sensors have a “resettable” sensing mechanism. The multiple acoustic wave modes are used for improved sensitivity and simultaneously use UV absorption measurement and SAW sensing mechanisms.
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Citations
21 Claims
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1. A SAW sensor comprising:
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an R-plane sapphire substrate;
a first and second layers of piezoelectric member comprised of zinc oxide disposed on said substrate;
a quantum well structure comprised of zinc oxide and magnesium zinc oxide heterostructure disposed on said first layer of said piezoelectric member;
input and output IDTs disposed on said second layer of said piezoelectric member;
a metal electrode disposed on said heterostructure and on a SAW path of said piezoelectric member;
a sensing coating disposed on top of said SAW path of the piezoelectric member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A SAW sensor comprising:
first and second channels, wherein said first and second channels each comprise;
an R-plane sapphire substrate;
a first and second layers of piezoelectric member comprised of zinc oxide disposed on said substrate;
a quantum well structure comprised of zinc oxide and magnesium zinc oxide heterostructure disposed on said first layer of said piezoelectric member;
input and output IDTs disposed on said second layer of said piezoelectric member;
a metal electrode disposed on said heterostructure and on a SAW path of said piezoelectric member; and
a chemically selective receptor coating being disposed on the quantum well structure of an exclusive one of said first and second channels. - View Dependent Claims (20, 21)
Specification