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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
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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
$10M funding over 4 years 27 Projects 60 Faculty members, post-docs, and graduate students combined NASA Funded Hydrogen Research at UF UF NASA Funded Hydrogen Research Web Site: http://www.mae.ufl.edu/NasaHydrogenResearch
Research Thrust Areas Fuel Cells (PEM and SOFC) Hydrogen Production, Storage, and Transport Nano Sensors - Hydrogen Leak Detection Gas inlet H2 Gas outlet NASA Funded Hydrogen Research at UF Hydrogen-Selective Sensing at Room Temperature with ZnO Nanorods Single Crystal Nanowires H2 Production PEM FC micro grids & Cooling Plate
Application fields: Fuel leak detection for automobile, space shuttle, and aircraft. Fire detection (CO, CO2). Emission, hydrocarbon, and health monitor. Environmental control. Motivation
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. Group III Nitride
Ti/Al/Pt/Au Pt Ti/Au SiNx Al0.28Ga0.72N GaN Sapphire 50 µm Device Fabrication 2DEG Device Cross-section Optical microscopic image
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 Pt AlGaN GaN Hb Hi 2DEG Sensing Mechanism
20 Nitorgen 16 1% Hydrogen 12 Current(mA) 8 4 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Biased Voltage(V) Experimental Results ; ΔФB~ -50 meV @ room T
Room temperature Nitrogen 20 1% Hydrogen 16 12 Current(mA) 8 4 0 Biased Voltage(V) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Practical Problem-False Alarm 50 °C 1. Thermal effect to semiconductor and Schottky contact. 2. Voltage drift
Differential Diodes Optical microscopic image
Wireless Sensor Module Client can deactivate alarm
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 Conclusions
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. Acknowledgements
Hydrogen Sensing Test Schematic illustration of gas sensor system
Comparison of Pd and Pt [1] [3] [2] 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
Gas Sensing Devices Schottky diode [1] HEMT[2] Resistor[3] [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).