Sol-Gel Derived Thin-Film Semiconductor Hydrogen Gas Sensor

We present the results of investigations of thin-film hydrogen sensors that show high sensitivity at low operating temperatures. These hydrogen sensors are manufactured using the sol-gel technique which ensures high temperature stability of nanocrystalline grains in the SnO₂ films. It was established that the highest sensitivity of the sensors occurred at 100 - 130 ^{{ring operator}} C. The hydrogen sensitivity depends on the hydrogen concentration linearly starting at 50 ppm, and reaches 10⁴ at 5000 ppm. The response time was measured at 1-2 s and the times were less than 10 s. We show that compared to constant power supply, pulse heating of the sensor improves the stability of the sensor, reduces the sensitivity to humidity, and reduces performance drift. We consider the effects of the material substrates, technology of the comb-like electrodes, and catalyst preparations. Various possibilities of reducing CO gas cross sensitivity are also presented.