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Surface Acoustic Wave Devices on Nitrides

Surface Acoustic Wave Devices on Nitrides. Wu Bin. EE598 Wide Bandgap Semiconductors Instructor: Dr. Huili(Grace) Xing Department of Electrical Engineering University of Notre Dame. Outline. Introduction Surface Acoustic Wave (SAW) device structure SAW devices as filters

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Surface Acoustic Wave Devices on Nitrides

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  1. Surface Acoustic Wave Devices on Nitrides Wu Bin EE598 Wide Bandgap Semiconductors Instructor: Dr. Huili(Grace) Xing Department of Electrical Engineering University of Notre Dame

  2. Outline • Introduction • Surface Acoustic Wave (SAW) device structure • SAW devices as filters • SAW devices as sensors • Wide bandgap material for SAW devices

  3. What Is SAW and How It Works -- A very brief description Surface acoustic waves (SAW) is the general name for the waves that propagate at the surface of solids, whose displacement amplitudes undergo exponential decay beneath this surface, similar to the ones that propagate on the water surface. Typically almost all of the energy is localized within a depth of two wavelengths. The SAW industry uses mainly Rayleigh waves, which are named after Lord Rayleigh. For applications in electronics, the piezoelectric effect is used to convert electrical energy into acoustic wave energy and vice versa. Information carried by the surface acoustic waves along the surface of a crystal substrate may be processed during propagation. The most common processing techniques involve either the time delay of the signal, which depends on the geometry of the device and the acoustic velocity, or the amplitude of the signal which can be varied or "weighted" by controlling the efficiency of the piezoelectric transduction.

  4. The Interdigital Transducer (IDT) The IDT comprises two sets of interpenetrating metallic electrodes fabricated photolithographically on the surface of a piezoelectric substrate. Atypical SAW device contains two such IDTs, one as input transducer, the other as output transducer to convert the SAW back to the electrical domain, e.g. delay or filtering.

  5. Some IDT Designs

  6. Some More IDT Designs

  7. SAW Device As Bandpass Filter

  8. Simple Calculation Considering The Merit of SAW Devices

  9. Small SAW Devices

  10. Small SAW Devices

  11. SAW Device As Sensor m is mass, c is stiffness,  is dielectric constant,  is surface conductivity, T is the temperature, and p is the pressure.

  12. SAW Device As Sensor

  13. Why Nitrides ?

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