Study of porous silicon gas sensor

Porous silicon (Si) and porous poly-Si organic and humidity vapor sensors have been studied. For aluminum (Al)/porous Si/p-Si/Al Schottky diode sensor, the sensitivity compared to air at room temperature in 2600 ppm acetone, methanol, 2-propanol and ethanol vapor are about 400, 500, 1000 and 4000% respectively. Sensitivity for 800-2600 ppm ethanol is 200 to 4000%. The sensor can be converted into an Al/porous Si/Al resistor sensor with sensitivity of about 500 times for a humidity change of 43-75%. Both sensors have response time of about 0.5 min and sensitivity is repeatable and stable with time. The porous Si sensor can be integrated into other VLSI Si devices to form novel microelectronic systems.