Multispecies Automotive Gas Sensors Based on Gallium Nitride – CLEANING

Introduction:
The use of real-time knowledge of the concentration of NO, NO2, and NH3 three gases would allow car manufacturers to meet the upcoming stringent EURO 7 anti-pollution measures for diesel engines. Knowledge of the concentration of each of these species will also enable engines to run leaner (i.e. more fuel efficient) while still meeting the anti-pollution requirements. The current market is dominated by a technology that makes use of an electrochemical fuel cell called the Nernst cell. Our proposed technology has the potential to revolutionize the field of automotive sensors. It consists of nano-structured semiconductors based on gallium nitride. the development of new technologies for selective detection of NH3, NO, and NO2 would be a critical enabler of superior depollution and control systems and thus create decisive advantages in the more regulated markets (EU, US, Japan, China). The control of intellectual property related to this superior pollution control system would allow extraction of value not only for the chemical sensor itself (which could be produced with a price near 1 to 5 €), but also for the whole system.

Objectives:
The primary objective of CLEANING is to demonstrate a gas sensor making use of nanotechnology that can simultaneously and selectively detect NO, NO2, and NH3 concentrations while meeting the expected Euro 7 stability, temperature, and response time requirements. The sensor will be based the high eletron mobility transistor (HEMT) and will make use of intellecutally property regarding BGaN materials in sensing and in HEMT sensor design, which is based on two French patents applied for in Feb. 2016 by PSA. Additionally, we will perform experiments in order to estimate the reliability of sensors in a package compatible with exisiting sensor form factors.

Preliminary work:
Perhaps the best indicator of the capacity of the consortium to produce results is our strong experimental validation of the basic semiconductor sensors. These initial efforts have demonstrated the excellent performance of both Schottky diode sensors and AlGaN/GaN HEMT gas sensors making use of new materials and associated nanostructuring of semiconductor and metal. These sensors show a strong change in current in response to NO2, NO, and NH3, with a detection limit of 20 parts per billion. We have also demonstrated repeatability to within 1.2 ppm in the laboratory while operating in a linear regime across the 1 to 500 ppm concentration range. With the packaging expertise included in this project, we should be able to package these laboratory results and to demonstrate that one can meet the requirements of Euro 7 while operating in a linear regime. We have demonstrated total selectivity between NO2 and NO or NH3. We also see weak cross-sensitivity to 21% oxygen. This work has led to a paper submitted to Applied Physics Letters and two more in preparation for submission. Two patents were applied for in February 2015. The inventions make use of innovative materials and processing techniques that can be achieved in standard semiconductor manufacturing environments, not requiring the addition of costly fabrication chemistries to standard GaN production lines. These initial results have been obtained over several years on very limited funding. The fact that the partners have been working together nonetheless shows the strong commitment to the project by the industrial partner.

Consortium and work plan: The experienced team has formed a clear and balanced work plan. The industrial is Peugeot-Citroen PSA, who has already contributed a PhD student, a car for testing, equipment funding, and legal services for two patent filings. The academic partners are leaders in their field, including GT-CNRS UMI (Metz, France), IEMN (Lille), and LN2 UMI (Sherbrooke, Canada).