In this paper a new C-MOS compatible fabrication process is presented for a
nitrogen dioxide porous silicon (PS) sensor. Electrically insulated PS sen
sing layers and even free-standing PS membranes have been obtained by front
side electrochemical micromachining, reducing in this way electrical leaka
ge towards the crystalline substrate. The electrical behavior of the device
in a controlled environment was measured by means of a volt-amperometric t
echnique at constant bias. A huge variation of the current was detected at
RT for NO2 concentrations as low as 200 ppb (DeltaG/G = 111). The interfere
nce of humidity, ethanol, methanol, CO and ozone is also discussed. (C) 200
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