Effects of interface energy modification in solution-processed In2O3 thin film transistors for sensing applications

- The active layer was patterned using interface energy modification with octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) and UV exposure.
- The patterned active layer led to reduced parasitic resistance resulting in a leakage current during transistor operation.
- Modified interface energy at the channel area affected the electrical characteristics of the thin film transistors.
- We confirmed that high interface energy leads better wetting of metal oxide precursor solution to improve performances.

Thin film transistors (TFTs) based on metal oxides have high mobility, transparency, and excellent stability, and are considered to be a key part of the next generation transparent electronic devices. Solution-processed metal oxide thin films using the sol-gel method has enabled the deposition of metal oxide thin films without a vacuum system, and it allows metal oxide TFTs to be fabricated more efficiently at low cost and over a large area through a simple process. In this study, we fabricated In2O3 using the sol-gel method and adopted various self-assembled monolayers (SAMs) to modify the interface between the semiconductor and dielectric layer. We used octadecyltrichlorosilane as a hydrophobic surface and partially removed it through exposure to UV radiation to form a patterned semiconductor using a simple spin-coating procedure that remarkably reduced the leakage current. 3-aminopropylsilane, (3-mercaptopropyl)trimethoxysilane, and cyclopentadienyltrimethylsilane as SAM materials and toluene and water as solvents to dilute them were used to modify the surface of the SiO2. We measured the contact angle under various conditions and the electrical characteristics of the TFTs annealed in various temperatures of 230, 250, and 300 °C to confirm the effect of interface energy modification, and concluded that surface energy affected the mobility of the In2O3 transistors and the lower surface energy enhanced the mobility of the TFTs.