Low frequency noise analysis on organic thin film transistors

Abstract

Bottom-contact organic field-effect transistors (OFETs) based on poly(3-hexylthiophene) with different channel lengths were fabricated under different substrate pretreatment process conditions. These OFET devices were characterized using low frequency noise (LFN) spectroscopy, and the device performance parameters were correlated with the level of LFN. It is observed that the devices with higher noise levels showed poorer device properties when compared with the devices operated at same Ids of the same channel length. It is also observed that the noise level increased with the increase in channel length for devices with the same pretreatment conditions, which is due to increased trapping and detrapping in the channel material interface domain. The OFET device operating around the threshold voltage Vth will have a 1/f noise slope that is flatter, having a gradient that is smaller in magnitude. The threshold voltage of a device can thus be observed to be at the gate voltage in which 1/f noise intensity is the highest at low frequencies. © 2008 American Institute of Physics.