Effect of molybdenum electrode annealing on the interface properties between metal and pentacene

Abstract

Contact resistance between molybdenum (Mo) electrode and pentacene was studied with transmission line method (TLM). The Mo electrodes were annealed at 200 degrees C, 400 degrees C, 600 degrees C and 800 degrees C for 1 h and pentacene layer of 300 angstrom thickness was vacuum deposited on patterned Mo to form Mo-pentacene contact. Current-voltage measurement for Mo-pentacene contact showed linear relationship and it was confirmed that ohmic contact was formed. XRD and AFM measurements showed that Mo could be crystallized at annealing temperatures above 600 degrees C. 800 degrees C annealed Mo showed larger grains and work function was increased from 4.60 eV to 4.80 eV due to the decrease in defect density. The contact resistance was reduced down to 11.2 M Omega cm from 37.8 M Omega cm of as-deposited Mo. Also the pentacene film deposited on annealed Mo was denser with better crystallinity. Bottom contact organic field-effect transistor made with 800 degrees C annealed Mo showed better performance than as deposited Mo. (C) 2008 Elsevier B.V. All rights reserved.