Impact of proton-beam irradiation on the electrical reliability and performance of LTPS and a-IGZO thin-film transistors

초록

We investigate the impact of 5 MeV proton beam irradiation on the electrical reliability of low-temperature polycrystalline silicon (LTPS) and amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). After irradiation, the threshold voltage (Vth) of a-IGZO TFTs shifted from 0.31 to - 7.87 V, while field-effect mobility (mu FE) increased from 8.4 to 11.7 cm2/V center dot s due to oxygen vacancy (Vo) formation, enhancing channel conductivity. In contrast, LTPS TFTs exhibited severe degradation, with Vth shifting from - 3.18 to - 33.51 V and mu FE dropping from 78.9 to 0.01 cm2/V s. Bias temperature instability tests showed significant deterioration in irradiated LTPS TFTs, whereas a-IGZO TFTs remained stable. This is attributed to the metastable a-IGZO lattice, which suppresses radiation-induced defect formation, whereas the LTPS lattice undergoes amorphization. X-ray Photoelectron Spectroscopy (XPS), and density of states (DOS) confirmed these mechanisms. Finally, we confirmed electrical performance recovery of irradiated TFTs through rapid thermal annealing (RTA) process. These findings provide insights into TFT degradation under radiation exposure and highlight the potential of a-IGZO and LTPS TFTs for radiation-hardened applications in radiography, military, aviation, and aerospace industries.

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