Observation of oxygen gas effect on porous silicon-based sensors

Electrical Properties of Porous Silicon for N2 Gas Sensor

“…The developed surface of our layer is on the order of 200 m 2 /cm 3 . Since the initial doping density of the Si is of the order of 6 × 10 15 cm -2 , there is enough density of dangling bonds to passivate the free carriers (only a few percent of the density of dangling bonds are necessary) [9]. The integration of Poisson's equation leads to a simple relation between depleted region (W) and density (σ), given by:…”

“…This mechanism includes the dipole moment of the adsorbed species, promoting an enhancement of the total current through the porous layer. The latter [9] is the chemical reactions between dangling bonds and adsorbed molecules occur inside pores, due to the adsorbed species, when they are oxidized; therefore, there is an improved passivation of dangling bonds, which enhances the conductivity [29]. And in turn change the behavior of PSi gas sensors, such as the sensitivity, etc.…”

“…The involved sensing mechanisms are generally associated with a change in the free carrier concentration in the porous layer due to adsorbed molecules, or changes in the dielectric constant due to gas condensation inside the pores; the sensed quantity is generally a conductance/current or capacitance [1,9].…”

“…In these studies, the electrical and optical response of PSi-based sensors has been investigated in the gas medium by performing conductance, capacitance [9][10][11][12] and photoluminescence (PL) measurements [13,14]. Both capacitive and ionic sensing modes in PSi are described by Anderson et al [10], Motohashi et al [15] expressed gas identification by a single gas sensor using PSi as the sensitive material; Stievenard and Deresmes [3] proposed a simple model based on dangling bonds to explain quantitatively the electrical behavior of Au-porous Si junction in the presence of various gases.…”

“…In this study, we probe the effects of anodization parameters on PSi sensor response. The most appealing features of PSi sensors are their low cost and the simplicity of fabrication [9].…”