Role of Self-Assembled Monolayers on Improved Electrical Stability of Amorphous In-Ga-Zn-O Thin-Film Transistors

• Main Authors: Du, Xiaosong, Flynn, Brendan T, Motley, Joshua R, Stickle, William F, Bluhm, Hendrik, Herman, Gregory S
• Format: Journal Article
• Language: English
• Published: 02-08-2014
• Subjects: Physics - Chemical Physics; Physics - Materials Science
• DOI: 10.48550/arxiv.1408.0330

ECS J. Solid State Sci. Technol. 2014 3(9): Q3045-Q3049 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.