Detecting Volatile Organic Compounds in the ppb range with platinum-gate SiC-Field Effect Transistors

In this work, the use of a platinum gate gas-sensitive SiC Field Effect Transistor (SiC-FET) was studied for the detection of low concentrations of hazardous Volatile Organic Compounds (VOC). For this purpose, a new gas mixing system was built providing VOCs down to sub-ppb levels by permeation ovens and gas pre-dilution. Measurements have shown that benzene, naphthalene and formaldehyde can be detected in the ppb range and indicate a detection limit of 1-2 ppb for benzene and naphthalene. The sensitivity is high with a response of 5.5 mV for 10 ppb naphthalene in a humid atmosphere (at 20% relative humidity) and with additional 2 ppm ethanol the response to naphthalene was still 1.3 mV. Formaldehyde can be detected down to approximately 100 ppb under humid conditions. This is the first time that a metal gated SiC-FET was used to detect hazardous VOCs in the low ppb range making SiC-FETs suitable candidates for indoor air quality applications.