Low‐<i>k</i> Insulators as the Choice of Dielectrics in Organic Field‐Effect Transistors

TLDR

Insulator–semiconductor interactions critically influence carrier transport, morphology, and density of states, with high‑permittivity dielectrics enhancing carrier localization via interfacial dipole fields. The study introduces a new gate‑insulator‑induced effect on OFET operation and examines its implications for band‑like semiconductors. The authors examined the effect by testing low‑k dielectrics on several disordered organic semiconductor materials. They found that low‑k dielectrics yield significant performance benefits compared to the prevailing trend of high‑permittivity dielectrics for low‑voltage operation.

Abstract

Abstract In this paper, we present a new effect influencing the operation of organic field‐effect transistors resulting from the choice of gate insulator material. In a series of studies it was found that the interaction between the insulator and the semiconductor materials plays an important role in carrier transport. The insulator is not only capable of affecting the morphology of the semiconductor layer, but can also change the density of states by local polarization effects. Carrier localization is enhanced by insulators with large permittivities, due to the random dipole field present at the interface. We have investigated this effect on a number of disordered organic semiconductor materials, and show here that significant benefits are achievable by the use of low‐ k dielectrics as opposed to the existing trend of increasing the permittivity for low operational voltage. We also discuss fundamental differences in the case of field‐effect transistors with band‐like semiconductors.