Reactively sputtered In xV yO z films for detection of NO x, D 2, and O 2

Abstract

Depletion-mode 4H-SiC field effect transistors (FETs) responding down to 0.002 mbar of NO x gas at a temperature of 300 °C were realized. A mixture of indium oxide (InO x ) and vanadium oxide (VO x ) was deposited by RF magnetron reactive sputtering as a gate material. The responses to NO x , 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 NO x 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 °C for NO x 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 NO x . The optimum temperature of operation for detection of D 2 is determined to be between 25 and 100 °C. In this range no significant responses to O 2 and NO x are observed, indicating that the sensor is very suitable for D 2 detection at very low temperatures.