Electrical properties of Al/PTB7-Th/n-Si metal-polymer-semiconductor Schottky barrier diode

Abstract

In the present study, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th) was used to fabricate a novel Al/PTB7-Th/n-Si metal-polymer-semiconductor (MPS) Schottky barrier diode (SBD). The Al/PTB7-Th/n-Si MPS SBD was prepared by employing a spin-coating system and a thermal evaporator for the deposition of PTB7-Th thin film and metal contacts, respectively. The electrical properties of the Al/PTB7-Th/n-Si MPS SBD were investigated by current-voltage method at room temperature in order to extract its main electrical parameters such as ideality factor (n), barrier height (Φb0), series resistance (Rs) and shunt resistance (Rsh). The I–V characteristics revealed nonlinear behavior due to the effect of Rs and ideality factor larger than unity. From the I–V curves, the values of ideality factor and barrier height of the diode were found to be 3.5 and 0.58 eV, respectively. The electrical parameters were verified by Cheung's and Norde's functions. The parameters determined by all the three methods were found to be in great agreement. The conduction mechanism of the diode was also studied. The simple and cost effective approach used for the fabrication of Al/PTB7-Th/n-Si MPS SBD demonstrates its potential for being used in the state-of-the-art high-quality electronic and optoelectronic devices.