High-Performance and Radiation-Hardened Solution-Processed ZrLaO Gate Dielectrics for Large-Area Applications

Yuxiao Fang; Chun Zhao; Ivona Z Mitrovic; Cezhou Zhao

doi:10.1021/acsami.1c13633

High-Performance and Radiation-Hardened Solution-Processed ZrLaO Gate Dielectrics for Large-Area Applications

ACS Appl Mater Interfaces. 2021 Oct 27;13(42):50101-50110. doi: 10.1021/acsami.1c13633. Epub 2021 Oct 12.

Authors

Yuxiao Fang^{1

2}, Chun Zhao^{1

3}, Ivona Z Mitrovic¹, Cezhou Zhao^{1

3}

Affiliations

¹ Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ, United Kingdom.
² Printable Electronics Research Center, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
³ Department of Electrical and Electronic Engineering, Xi'an Jiaotong-Liverpool University, Suzhou 215123, China.

PMID: 34636544
DOI: 10.1021/acsami.1c13633

Abstract

Radiation hardness is important for electronics operating in harsh radiation environments such as outer space and nuclear energy industries. In this work, radiation-hardened solution-processed ZrLaO thin films are demonstrated. The radiation effects on solution-processed ZrLaO thin films and InO_x/ZrLaO thin-film transistors (TFTs) were systemically investigated. The Zr_0.9La_0.1O_y thin films demonstrated excellent radiation hardness with negligible roughness, composition, electrical property, and bias-stress stability degradation after radiation exposure. The metal-oxide-semiconductor capacitors (MOSCAPs) based on Zr_0.9La_0.1O_y gate dielectrics exhibited an ultralow flat band-voltage (V_FB) sensitivity of 0.11 mV/krad and 0.19 mV/krad under low dose and high dose gamma irradiation conditions, respectively. The low dose condition had a 103 krad (SiO₂) total dose and a 0.12 rad/s low dose rate, whereas the high dose condition had a 580 krad total dose and a 278 rad/s high dose rate. Furthermore, InO_x/Zr_0.9La_0.1O_y thin-film transistors (TFTs) exhibited a large I_on/I_off of 2 × 10⁶, a small subthreshold swing (SS) of 0.11 V/dec, a small interface trap density (D_it) of 1 × 10¹² cm^-2, and a 0.16 V threshold shift (ΔV_TH) under 3600 s positive bias-stress (PBS). InO_x/Zr_0.9La_0.1O_y TFT-based resistor-loaded inverters demonstrated complete swing behavior, a static output gain of 13.3 under 4 V V_DD, and an ∼9% radiation-induced degradation. Through separate investigation of the radiation-induced degradation on the semiconductor layer and dielectric layer of TFTs, it was found that radiation exposure mainly generated oxygen vacancies (V_o) and increased electron concentration among gate oxide. Nevertheless, the radiation-induced TFT instability was mainly related to the semiconductor layer degradation, which could be possibly suppressed by back-channel passivation. The demonstrated results indicate that solution-processed ZrLaO is a high-potential candidate for large-area electronics and circuits applied in harsh radiation environments. In addition, the detailed investigation of radiation-induced degradation on solution-processed high-k dielectrics in this work provided clear inspiration for developing novel flexible rad-hard dielectrics.

Keywords: high-k gate oxide; inverter; lanthanum oxide; radiation hardness; solution processed; zirconium oxide.