Room-temperature gas-sensing ability of PtSi/porous Si Schottky junctions

Gas-sensing ability of n-type PtSi/porous Si Schottky junctions is investigated at room temperature. These junctions exhibit a breakdown-type current-voltage (I-V) curve at low reverse bias voltages (5-15 V) due to very large electric fringing fields (10⁵-10⁶ V/cm) developed at the sharp edges and the bottom of the pores. Experimental results for selected gases are presented. Gases with inherent dipole moments tend to decrease the breakdown voltage. Gases without dipole moments do not affect the I-V curve directly, but they can replace gas content inside the pores and decrease the dipole moment of the ambient gas, which results in an increase in breakdown voltage. Based on these experiments, the possible application of this structure as a gas sensor at room temperature is discussed.