Mathematical modelling of tri-layer dielectric OTFT based on pentacene semiconductor for enhancing the electrical characteristics

Organic thin film transistors (OTFTs) are significant for several reasons because their design processes are less complicated than those of conventional silicon technology which requires complex photolithographic patterning techniques and high-temperature and high-vacuum deposition processes. The more complex procedures used in traditional Si technology can be replaced by low-temperature deposition and solution processing. OTFTs based on the single-layer dielectric medium are poor in reducing the leakage current among the source and drain channel due to the incompatible resistance of dielectric medium. The paper presents a model of a tri-layer dielectric medium based on the organic semiconductor pentacene. In this tri-layer OTFT, three different dielectric mediums are used, such as SiO₂, POM-H (PolyOxyMethylene-Homopolymer) and PEI-EP (PolyEthyleneImine–Epoxy resin), for reducing the leakage current and enhancing the mobility among the source and drain channel. The parameter values, such as drain current I_DS, threshold voltage V_t and mobility for the designed tri-layer dielectric OTFT, are evaluated and compared with the single layer and bi-layer OTFT models. Thus, the attained mobility, drain current and threshold voltage for the proposed OTFT model are 0.0215 cm²/(V·s), –4.44 mA for –10 V gate and –2.5 V drain voltage (V_DS) and threshold value 0.2445 V (V_t) for gate voltage –10 V (V_G). These attained parameter values are greater than the single- and bi-layer dielectric OTFT models. Thus, the mathematical modeling of the designed tri-layer dielectric OTFT model enhances the electrical characteristics of the other OTFT models.

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