Role of Self-Assembled Monolayers on Improved Electrical Stability of   Amorphous In-Ga-Zn-O Thin-Film Transistors
  Self-assembled monolayers (SAMs) have been used to improve both the positive and negative bias-stress stability of amorphous indium gallium zinc oxide (IGZO) bottom gate thin film transistors (TFTs). N-hexylphosphonic acid (HPA) and fluorinated hexylphosphonic acid (FPA) SAMs adsorbed on IGZO back channel surfaces were shown to significantly reduce bias stress turn-on voltage shifts compared to IGZO back channel surfaces with no SAMs. FPA was found to have a lower surface energy and lower packing density than HPA, as well as lower bias stress turn-on voltage shifts. The improved stability of IGZO TFTs with SAMs can be primarily attributed to a reduction in molecular adsorption of contaminants on the IGZO back channel surface and minimal trapping states present with phosphonic acid binding to the IGZO surface. 
Xiaosong Du, Brendan T. Flynn, Joshua R. Motley, William F. Stickle,   Hendrik Bluhm, and Gregory S. Herman
physics.chem-ph cond-mat.mtrl-sci