Effect of ammonia (NH 3) plasma treatment on silicon nitride (SiN x) gate dielectric for organic thin film transistor with soluble organic semiconductor

Abstract

The effect of an ammonia plasma treatment on silicon nitride (SiN x) gate dielectrics for organic thin film transistors (OTFTs) with soluble organic semiconductors (OSCs) was studied. Our OTFTs were fabricated by using the soluble derivatives of Poly(bi-thiophene) as the p-type polymer semiconductor material and SiN x thin films with nitrogen oxygen (N 2O) and ammonia (NH 3) plasma treatments as the gate dielectric. To improve the performance and stability of the OTFT devices, we studied the basic mechanism of the plasma treatment on the SiN x gate dielectric and the gold (Au) electrode surface. The SiN x-OTFTs with a NH 3 plasma treatment yielded the improved results in terms of a higher field-effect mobility ( μ fe) of 0.06 cm 2 V −1 S −1 with a lower interface charge trap density of 4.45 × 10 −11 (cm 2 eV) −1 and a lower contact resistance of 0.384 MΩ-cm. The repulsive force of the soluble OSC solvent was reduced at the edge of the source-drain (S-D) electrode due to the difference between the surface energies of the channel region and Au S-D electrodes.