Influence of Dielectric and Semiconductor Thickness on Performance Parameters in Organic Field-Effect Transistors

The mobility and current-handling capabilities of Organic Field-Effect Transistors (OFETs) are critical parameters that determine their electrical performance, significantly influenced by material properties and layer thicknesses. In this study, we present a simulation-based analysis of an OFET structure, employing pentacene as the active layer and hafnium dioxide (HfO₂) as the dielectric material. The electrical characteristics of the OFET are investigated by systematically varying the thickness of the dielectric layer (from 5 nm to 7 nm) and the pentacene layer (from 10 nm to 30 nm), while keeping one parameter constant at a time. Key performance metrics such as drain current, transconductance, and charge carrier mobility are analyzed. Our findings reveal that while a thinner dielectric layer enhances capacitance, the transconductance effect has a more pronounced impact on mobility, likely due to changes in the transverse electric field. Additionally, increasing the pentacene layer thickness leads to a reduction in mobility. The highest mobility values obtained are 0.0708 cm²/Vs for a 7 nm dielectric thickness and 0.0655 cm²/Vs for a 10 nm pentacene thickness. These results provide valuable insights into the optimization of OFET performance through structural parameter tuning.