Marco Sarcletti, Thomas Schmaltz, Marcus Halik
We report on a mutual correlation between the substrate temperature during semiconductor deposition and the surface energy of the gate dielectric on the charge carrier mobility in bottom gate top contact organic field effect transistors (OFETs) with N,N′-diphenyl-3,4,9,10-perylene tetracarboxylic diimide (DP-PDI) as organic semiconductor.
The gate dielectric consists of a thin gate aluminum oxide and a self-assembled monolayer (SAM) with which the surface energy of the hybrid dielectric is tuned. The substrate temperature during evaporation of the DP-PDI semiconductor was systematically varied to obtain the best charge carrier mobility for each SAM. We found that the optimum substrate temperature correlates with the surface energy. Devices with low surface energy reach best mobility at higher substrate temperatures than devices with a higher surface energy.