Controlling threshold voltage and leakage currents in vertical organic field-effect transistors by inversion mode operation

Abstract

The interest in vertical organic transistors as a means to overcome the limitations of conventional organic field-effect transistors (OFETs) has been growing steadily in recent years. Current vertical architectures, however, often suffer from a lack of parameter control, as they are limited to certain materials and processing techniques, making a controlled shift of, e.g., the transistor threshold voltage difficult. In this contribution, we present a vertical OFET (VOFET) operating in the inversion regime. By varying the thickness or doping concentration of a p-doped layer in an otherwise n-type VOFET, we are able to shift the threshold voltage in a controlled manner from 1.61 V (for a normal n-type VOFET) to 4.83 V (for the highest doping concentration of 50 mol. %). Furthermore, it is found that low doping concentrations of 20 mol. % can improve the Off state of the VOFET through reduction of the source-drain leakage current.

Lowering the Contact Barriers of 2D Organic F16CuPc Field‐Effect Transistors by Introducing Van der Waals Contacts

“…[ 13–16 ] Many efforts have been paid to lower the Schottky barrier heights (SBHs) in OFETs. Especially, chemical doping of the contact interface by metal oxides, [ 17–21 ] inorganic salts, [ 22–25 ] and organic compounds [ 26–30 ] has been demonstrated to effectively enhance the tunneling probability of carriers by reducing the depletion width. Unfortunately, due to the trade‐off between Schottky barrier and tunneling barrier, the optimized thickness of insertion layer is demanded to achieve the lowest contact resistance, and the instability and uncontrollable diffusion of chemical dopants still remain severe challenges.…”

Graphene and PbS quantum dot hybrid vertical phototransistor

“…The channel current increases significantly as the light irradiance increases, however the threshold voltage of the graphene/PbS QDcompositeVFEpTs does notchange under illumination, which is different from lateral hybrids FEpTs [17]. The vertical transistor threshold voltage under fixed source-drain bias can be expressed in the equation [36,37] ( )…”

A Review of Vertical Organic Transistors

“…Additionally, other short‐channel effects are also inherent to pseudo‐VOFETs. In particular, threshold voltage roll‐off and increased off‐state current due to unintentional background doping are frequently observed; the latter effect can be partially mitigated by the choice of an appropriate semiconductor material …”