Subthreshold slope optimization for pentacene based organic tunnel field effect transistor

Abstract

Conventional Organic Thin Film Transistors (OTFTs) face significant challenges. Short-channel effects prevent current saturation when scaled to the nanoscale, while the thermionic transport mechanism limits the subthreshold swing to values above 60 mV/dec. To overcome these limitations, a Doped Lateral Organic Tunnel Field Effect Transistor (DL O-TuFET) is proposed. This work examines the influence of source and drain doping on device performance. The higher source doping enhances tunneling probability, while moderate drain doping reduces OFF-current and improves subthreshold swing. Furthermore, the impact of trap density in the active material on device characteristics is investigated. Key performance metrics, including threshold voltage, subthreshold swing, ON/OFF ratio, and RF parameters, are quantitatively analyzed. Simulations using Silvaco TCAD reveal that an optimized source and drain doping of 1 x 10²¹ cm⁻³ and 1 x 10¹⁹ cm⁻³, respectively, yields promising results. The device exhibits a threshold voltage of −0.963 V, a subthreshold swing of 12.5 mV/decade, an ON/OFF ratio in the range of 10¹⁷, a maximum electric field of 5.41 × 10⁷ V/cm, and a maximum band-to-band tunneling rate of 7.94 x 10³²/cm³s. These values contribute to a maximum ON-current of 83.6 μA, making the DL O-TuFET a viable alternative to conventional OTFTs. Moreover, a maximum cut-off frequency of 0.66 GHz demonstrates its suitability for higher-speed applications.