Tuning of the Sensitivity of Porous Silicon JFET Gas Sensors

In this work, electrical tuning of the sensitivity of an integrated solid‐state gas sensor is demonstrated. The sensor, namely PSJFET—Porous Silicon Junction Field Effect Transistor, consists of a p‐channel JFET with an additional PS sensing gate on its top. The sensor current value is proportional to the $NO2$ concentration in the environment, that is $IDS = S⋅[NO2],$ at least in the range investigated (between 100 ppb and 500 ppb). Interestingly, and differently from most of gas sensors reported in the literature, the normalized sensor sensitivity $S = dIDS/(IDS0⋅d[NO2])$ can be effectively tuned by changing the voltage value of the electrical gate terminal of the JFET device. This feature allows the fabrication of gas sensors with superior performances: for example, it can be exploited to compensate for aging‐induced degradation of the sensitivity during the sensor life‐time. It is worthy of mentioning that, such an effect can be obtained without any increase of the sensor power dissipation, due to the high impedance of the gate terminal of the PSJFET.