Reactively sputtered InxVyOz films for detection of NOx, D2, and O2

Depletion-mode 4H-SiC field effect transistors (FETs) responding down to 0.002 mbar of NOx gas at a temperature of 300 degrees C were realized. A mixture of indium oxide (InOx) and vanadium oxide (VOx) was deposited by RF magnetron reactive sputtering as a gate material. The responses to NOx D-2 and O-2 gases were investigated as a function of the operating temperature for different partial pressures of the test gases. The sensor is very sensitive to NOx and its performance is strongly dependent on the gas concentrations and operating temperature. The response to D-2 has been found to be maximal at room temperature. The optimum detection temperatures occur in the range 275-325 degrees C for NOx with these catalysts. The response to both O-2 and D-2 is very low in this temperature range, suggesting that the sensor is very suitable for selective detection of NOx The optimum temperature of operation for detection of D-2 is determined to be between 25 and 100 degrees C. In this range no significant responses to O-2 and NOx are observed, indicating that the sensor is very suitable for D-2 detection at very low temperatures. (C) 2006 Published by Elsevier B.V.