wireless hydrogen sensor networks using gan-based devices
DESCRIPTION
Wireless Hydrogen Sensor Networks Using GaN-based Devices. Travis Anderson 1 , Hung-Ta Wang 1 , Byoung Sam Kang 1 , Fan Ren 1 , Changzhi Li 2 , Zhen Ning Low 2 , Jenshan Lin 2 , Stephen Pearton 3 1 University of Florida, Chemical Engineering - PowerPoint PPT PresentationTRANSCRIPT
University of Florida NHA Hydrogen Conference, March 21, 2007
Wireless Hydrogen Sensor Networks Using GaN-based Devices
Travis Anderson1, Hung-Ta Wang1, Byoung Sam Kang1, Fan Ren1, Changzhi Li2, Zhen Ning Low2,
Jenshan Lin2, Stephen Pearton3
1 University of Florida, Chemical Engineering 2 University of Florida, Electrical and Computer Engineering 3 University of Florida, Materials Science and Engineering
University of Florida NHA Hydrogen Conference, March 21, 2007
NASA Funded Hydrogen Research at UF
• $10M funding over 4 years• 27 Projects• 60 Faculty members, post-docs, and graduate
students combined
UF NASA Funded Hydrogen Research Web Site:
http://www.mae.ufl.edu/NasaHydrogenResearch
University of Florida NHA Hydrogen Conference, March 21, 2007
NASA Funded Hydrogen Research at UF
Research Thrust Areas
• Fuel Cells (PEM and SOFC)
• Hydrogen Production, Storage, and Transport
• Nano Sensors - Hydrogen Leak DetectionGas inlet
H2
Gas outlet Single Crystal NanowiresHydrogen-Selective
Sensing at Room Temperature with ZnO
NanorodsH2 ProductionPEM FC micro grids & Cooling Plate
University of Florida NHA Hydrogen Conference, March 21, 2007
Motivation
Application fields:• Fuel leak detection for
automobile, space shuttle, and aircraft.
• Fire detection (CO, CO2).
• Emission, hydrocarbon, and health monitor.
• Environmental control.
University of Florida NHA Hydrogen Conference, March 21, 2007
Group III Nitride
• Outstanding mechanical and electronic properties
• Controllable wide range band gap(3.4eV-6.2eV AlGaN)
• High thermal stability
• Chemical inertness
• AlGaN/GaN 2DEG for high power and high frequency.
University of Florida NHA Hydrogen Conference, March 21, 2007
Device Fabrication
50 µm
Optical microscopic image
GaN
Sapphire
Al0.28Ga0.72N
Ti/AuPt
SiNx
Ti/Al/Pt/Au
Device Cross-section
2DEG
University of Florida NHA Hydrogen Conference, March 21, 2007
Sensing Mechanism
• H22H(chemisorption on Pt)
• Diffusion of H atom.
H2(gas) 2Hs 2Hb 2Hi
• Creation of a polarized layer at the interface
• Decrease of barrier height. (Schottky diode); increase of channel cross-section. (FET)
H2
Hs
Hb
2DEG
HiPt
AlGaN
GaN
University of Florida NHA Hydrogen Conference, March 21, 2007
Experimental Results
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0
4
8
12
16
20
Cu
rren
t (m
A)
Biased Voltage (V)
Nitorgen
1% Hydrogen
1expexp2**F
nkT
eV
kT
qTAJ B ; ΔФB~ -50 meV @ room T
University of Florida NHA Hydrogen Conference, March 21, 2007
Practical Problem-False Alarm
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0
4
8
12
16
20
Cu
rren
t (m
A)
Biased Voltage (V)
Nitrogen
1% Hydrogen
Room temperature 50 °C
1. Thermal effect to semiconductor and Schottky contact.
2. Voltage drift
University of Florida NHA Hydrogen Conference, March 21, 2007
Differential Diodes
Optical microscopic image
University of Florida NHA Hydrogen Conference, March 21, 2007
1% Hydrogen Test
University of Florida NHA Hydrogen Conference, March 21, 2007
Hardware Design
Warm up: 30 seconds 1s5s
Monitor
Tx data
Monitor
Tx data
Monitor
Tx data
Monitor
Tx data
Power Up
Power Down
1s5s 1s5s 1s5s
University of Florida NHA Hydrogen Conference, March 21, 2007
Wireless Sensor Module
Client can deactivate alarm
University of Florida NHA Hydrogen Conference, March 21, 2007
Field Test
University of Florida NHA Hydrogen Conference, March 21, 2007
Conclusions
GaN-based sensors demonstrate rapid response (<1s) and
reversibility Differential sensor devices eliminate sensitivity to
temperature and voltage drifts TiB2 can be used in ohmic contacts to improve reliability These sensors have been implemented in a wireless
detection circuit Field testing is underway at Greenway Ford, Orlando, FL We are seeking investors for a startup company
University of Florida NHA Hydrogen Conference, March 21, 2007
Acknowledgements
This work at UF is supported by:
1. NSF (CTS-0301178, monitored by Dr. M.
Burka and Dr. D. Senich)
2. NASA Kennedy Space Center Grant NAG
10-316 monitored by Mr. Daniel E. Fitch.
University of Florida NHA Hydrogen Conference, March 21, 2007
Hydrogen Sensing Test
Schematic illustration of gas sensor system
University of Florida NHA Hydrogen Conference, March 21, 2007
Room Temperature Test
University of Florida NHA Hydrogen Conference, March 21, 2007
50 °C Test
University of Florida NHA Hydrogen Conference, March 21, 2007
Comparison of Pd and Pt
Reference:[1] W. Eberhardt, F. Greuter, E. W. Plummer, Phys. Rev. Lett. 46, 1085 (1981).[2] http://www.rebresearch.com/H2sol2.htm[3] http://www.rebresearch.com/H2perm2.htm
[2]
[1][3]
University of Florida NHA Hydrogen Conference, March 21, 2007
Gas Sensing Devices
Resistor[3]Schottky diode [1] HEMT[2][1] B. S. Kang, F. Ren, B. P. Gila, C. R. Abernathy and S. J. Pearton, Appl. Phys. Lett. 84 1123 (2004).
[2] B. S. Kang, R. Mehandru, S. Kim, F. Ren, R. C. Fitch, J. K. Gillespie, N. Moser, G. Jessen, T. Jenkins, R. Dettmer, D. Via, A. Crespo, B.
P. Gila, C. R. Abernathy and S. J. Pearton, Appl. Phys. Lett. 84 4635 (2004).
[3] H. T. Wang, B. S. Kang, F. Ren, L. C. Tien, P. W. Sadik, D. P. Norton, S. J. Pearton, Jenshan Lin, Appl. Phys. Lett. 86 243503 (2005).