In Situ Radiation Hardness Study of Amorphous Zn-In-Sn-O Thin-Film Transistors with Structural Plasticity and Defect
Dongil Ho1, Sunwoo Choi1, Hyunwoo Kang1
1Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbom-ro, Mapo-gu, Seoul 04107, Republic of Korea.
ACS Applied Materials & Interfaces
|July 5, 2023
Summary
Amorphous zinc-indium-tin oxide (ZITO) thin-film transistors (TFTs) show superior radiation resistance. These ZITO TFTs demonstrate excellent stability under gamma-ray irradiation, making them ideal for harsh environments.
Area of Science:
- Materials Science
- Semiconductor Physics
- Radiation Effects
Background:
- Metal-oxide thin-film transistors (TFTs) are crucial for various electronic applications.
- Assessing the radiation hardness of TFTs is essential for their deployment in environments exposed to ionizing radiation.
- Understanding degradation mechanisms under irradiation is key to developing robust electronic devices.
Purpose of the Study:
- To investigate the radiation hardness of solution-processed metal-oxide TFTs with varying metal compositions.
- To identify optimal materials and device structures for radiation-resistant TFTs.
- To elucidate the degradation mechanisms of TFTs under ionizing radiation exposure.
Main Methods:
- Ex situ and in situ radiation hardness experiments were conducted on TFTs with different metal compositions.
- Amorphous zinc-indium-tin oxide (ZITO) was synthesized and fabricated into TFTs.
- Device performance was analyzed before and after ionizing radiation exposure (gamma-ray irradiation at 15 kGy/h).
Main Results:
- Amorphous ZITO (Zn-In-Sn-O) with a 4:1:1 Zn/In/Sn ratio exhibited superior radiation resistance compared to other compositions like In-Ga-Zn-O.
- In situ irradiation revealed negative threshold voltage shifts, increased mobility, off-current, and leakage current.
- Degradation mechanisms involve increased channel conductivity, charge buildup in interfaces and dielectrics, and trap-assisted tunneling.
Conclusions:
- ZITO is an optimal radiation-resistant channel layer for TFTs due to the synergistic properties of Zn, Sn, and In.
- Radiation-hard oxide-based TFTs were successfully demonstrated using a ZITO channel, thin SiO2 dielectric, and PCBM passivation.
- The developed ZITO TFTs show excellent stability with electron mobility of ~10 cm²/V s and a threshold voltage shift of <3 V under real-time gamma-ray irradiation.
