Enhanced Interfacial Integrity of Amorphous Oxide Thin-Film Transistors by Elemental Diffusion of Ternary Oxide Semiconductors

Seong-Pil Jeon; Jae Sang Heo; Insoo Kim; Yong-Hoon Kim; Sung Kyu Park

doi:10.1021/acsami.0c16068

Enhanced Interfacial Integrity of Amorphous Oxide Thin-Film Transistors by Elemental Diffusion of Ternary Oxide Semiconductors

ACS Appl Mater Interfaces. 2020 Dec 30;12(52):57996-58004. doi: 10.1021/acsami.0c16068. Epub 2020 Dec 17.

Authors

Seong-Pil Jeon¹, Jae Sang Heo^{2

3}, Insoo Kim², Yong-Hoon Kim³, Sung Kyu Park¹

Affiliations

¹ School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06980, Korea.
² Department of Medicine, University of Connecticut School of Medicine, Farmington, Connecticut 06030, United States.
³ School of Advanced Materials Science and Engineering and SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea.

PMID: 33332113
DOI: 10.1021/acsami.0c16068

Abstract

Low-temperature solution-processed oxide semiconductor and dielectric films typically possess a substantial number of defects and impurities due to incomplete metal-oxygen bond formation, causing poor electrical performance and stability. Here, we exploit a facile route to improve the film quality and the interfacial property of low-temperature solution-processed oxide thin films via elemental diffusion between metallic ion-doped InO_x (M:InO_x) ternary oxide semiconductor and AlO_x gate dielectric layers. Particularly, it was revealed that metallic dopants such as magnesium (Mg) and hafnium (Hf) having a small ionic radius, a high Gibbs energy of oxidation, and bonding dissociation energy could successfully diffuse into the low-quality AlO_x gate dielectric layer and effectively reduce the structural defects and residual impurities present in the bulk and at the semiconductor/dielectric interface. Through an extensive investigation on the compositional, structural, and electrical properties of M:InO_x/AlO_x thin-film transistors (TFTs), we provide direct evidences of elemental diffusion occurred between M:InO_x and AlO_x layers as well as its contribution to the electrical performance and operational stability. Using the elemental diffusion process, we demonstrate solution-processed Hf:InO_x TFTs using a low-temperature (180 °C) AlO_x gate dielectric having a field-effect mobility of 2.83 cm² V^-1·s^-1 and improved bias stability. Based on these results, it is concluded that the elemental diffusion between oxide semiconductor and gate dielectric layers can play a crucial role in realizing oxide TFTs with enhanced structural and interfacial integrity.

Keywords: low temperature; metal doping/diffusion; metal ionic radius; solution-processed amorphous oxide semiconductor (AOS); suppression of residual impurities/mobile ions; thin-film transistors (TFTs).