General model for charge carriers transport in electrolyte-gated transistors

TL;DR

This paper introduces a comprehensive charge transport model for electrolyte-gated transistors that accounts for non-ideal behaviors, including percolation effects and trap distributions, successfully fitting experimental data for various device types.

Contribution

The model uniquely integrates 2D/3D percolation, trap effects, and variable accumulation layer thickness, advancing understanding of non-ideal transistor behaviors.

Findings

Model accurately fits experimental EGT data

Explains non-linear low-voltage output behavior

Highlights impact of traps and accumulation layer on mobility

Abstract

Inspired by experimental observations related to electrolyte-gated transistors (EGTs) where non-ideals behaviors are shown and not described by just one theoretical model, we proposed a charge carriers transport model able to describe the typical modes of operation profiles as well as some non-ideals ones from electrolyte-gated field effect transistors (EGOFETs) and organic electrochemical transistors (OECTs). Our analysis include the effect of 2D or 3D percolation transport (PT) and also the influence of a shallow exponential traps distribution on the transport. Under these considerations, a non-constant accumulation layer thickness along the channel can be formed. Such dependence was included into our model in the effective mobility parameter dependent on the accumulation thickness. The accumulation thickness can depict 2D or 3D PT or even a transition between them. This transition can produce a non-ideal profile between the linear and saturation regimes in the output curve, region in which a protuberance/lump appears. Other analyzed phenomenon was the non-linear behavior for low drain voltage range in the output curve, even when considering an ohmic contact. According to this proposed model, this curve behavior is attributed to the traps distribution profile into the semiconductor and the very thin accumulation layer thickness close to the injection contact. It was also possible to analyze the conditions when the linear field effect mobility is higher or lower than the saturation one. Finally, EGOFET and OECT experimental data were successfully fitted with this model showing its versatility.