Surface Acoustic Surface Acoustic Wave Devices on Wave Devices on Nitrides Nitrides Wu Bin Wu Bin EE598 Wide Bandgap Semiconductor s Instructor: Dr. Huili(Grace) Xin g Department of Electrical Enginee ring
Feb 05, 2016
Surface Acoustic Surface Acoustic Wave Devices on Wave Devices on
NitridesNitridesWu BinWu Bin
EE598 Wide Bandgap SemiconductorsInstructor: Dr. Huili(Grace) XingDepartment of Electrical EngineeringUniversity of Notre Dame
OutlineOutline
IntroductionIntroduction Surface Acoustic Wave (SAW) deSurface Acoustic Wave (SAW) de
vice structurevice structure SAW devices as filtersSAW devices as filters SAW devices as sensorsSAW devices as sensors Wide bandgap material for SAW Wide bandgap material for SAW
devicesdevices
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.
What Is SAW and How It Works-- A very brief description
The Interdigital Transducer (IDT)The IDT comprises two sets of interpenetrating metallic electrodes fabricated photolithographically on the surface of a piezoelectric substrate.A typical 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.
Some IDT Designs
Some More IDT Designs
SAW Device As Bandpass FilterSAW Device As Bandpass Filter
mms
sm
SAW
ms
sm
EM
GHzf
f
f
3103101
3000
3.0101
103
1
69
9
8
0
00
00
Simple Calculation Simple Calculation Considering The Merit of Considering The Merit of
SAW DevicesSAW Devices
Small SAW DevicesSmall SAW Devices
Small SAW DevicesSmall SAW Devices
SAW Device As SensorSAW Device As Sensor
pp
TT
cc
mm
0
1
00 f
m is mass, c is stiffness, is dielectric constant, is surface conductivity, T is the temperature, and p is the pressure.
SAW Device As SensorSAW Device As Sensor
Why Nitrides ?Why Nitrides ?