We report on the analysis of nonlinear current-voltage characteristics exhibited by a set of blocking metal/SnO(2)/metal. Schottky barrier heights in both interfaces were independently extracted and their dependence on the metal work function was analyzed. The disorder-induced interface states effectively pinned the Fermi level at the SnO(2) surface, leading to the observed Schottky barriers. The model is useful for any two-terminal device which cannot be described by a conventional diode configuration.

Organic thin-film transistors (OTFTs) are miniaturized devices based upon the electronic responses of organic semiconductors. In comparison to their conventional inorganic counterparts, organic semiconductors are cheaper, can undergo reversible doping processes and may have electronic properties chiefly modulated by molecular engineering approaches. More recently, OTFTs have been designed as gas sensor devices, displaying remarkable performance for the detection of important target analytes, such as ammonia, nitrogen dioxide, hydrogen sulfide and volatile organic compounds (VOCs). The present manuscript provides a comprehensive review on the working principle of OTFTs for gas sensing, with concise descriptions of devices’ architectures and parameter extraction based upon a constant charge carrier mobility model. Then, it moves on with methods of device fabrication and physicochemical descriptions of the main organic semiconductors recently applied to gas sensors (i.e., since 2015 but emphasizing even more recent results). Finally, it describes the achievements of OTFTs in the detection of important gas pollutants alongside an outlook toward the future of this exciting technology.

The current–voltage ( I – V ) characteristics of metal–semiconductor junction (Au–Ni/SnO ₂ /Au–Ni) Schottky barrier in SnO ₂ nanowires were investigated over a wide temperature range. By using the Schottky–Mott model, the zero bias barrier height Φ _B was estimated from I – V characteristics, and it was found to increase with increasing temperature; on the other hand the ideality factor ( n ) was found to decrease with increasing temperature. The variation in the Schottky barrier and n was attributed to the spatial inhomogeneity of the Schottky barrier height. The experimental I – V characteristics exhibited a Gaussian distribution having mean barrier heights Φ ¯ B of 0.30 eV and standard deviation σ _s of 60 meV. Additionally, the Richardson modified constant was obtained to be 70 A cm ⁻² K ⁻² , leading to an effective mass of 0.58 m ₀ . Consequently, the temperature dependence of I – V characteristics of the SnO ₂ nanowire devices can be successfully explained on the Schottky–Mott theory framework taking into account a Gaussian distribution of barrier heights.