Rapid Response of Au/Porous-GaAs Humidity Sensor at Room Temperature

The sensitivity of n-type Au/porous-GaAs Schottky junction for humidity sensing at room temperature is presented here. These junctions exhibit a breakdown n-type behavior at their reverse bias I-V curve which depends on the amounts of relative humidity inside the chamber. H₂O is a polar gas, it causes changes in the electric fringing fields of Au/Porous-GaAs sensor affecting changes in it´s reverse I-V characteristics. At room temperature with 15% relative humidity the break down point was about 5.3 V. Which decreased down to 4.5 V when submitted to a relative humidity of 25%. The response time of our sensor is lower than 0.1 s and it´s recovery time is about 10 s. We have deposited Au on porous-GaAs sensor with dc magnetron sputtering in different thicknesses ranging from 10 to 125 nm. The best result was observed with a thickness of about 20 nm. Also Au/Porous-GaAs, Au/GaAs and Ag/porous-GaAs sensors were compared in this experiment.