Composition engineering for hysteresis suppression and enhanced electrical characteristics in ALD-Grown Indium–Gallium oxide thin-film transistors

초록

Back-end-of-line-compatible monolithic three-dimensional integration requires oxide semiconductor channel materials that combine low-temperature processability with stable electrical operation. Among binary oxide semiconductors, In2O3 is an attractive channel material owing to its high electron mobility; however, oxygen-deficiency-related defects often cause electrical instability, including threshold-voltage variation and hysteresis behavior. In this study, indium–gallium oxide (IGO) thin-film transistors (TFTs) were fabricated by atomic layer deposition (ALD), and the influence of Ga incorporation was systematically investigated using ALD supercycle engineering with different In:Ga cycle ratios. Increasing Ga incorporation progressively suppressed the crystallinity of In2O3 while modifying the chemical bonding environment of the films. These changes were accompanied by reduced oxygen-deficiency-related defect characteristics, decreased effective trap density, and suppressed hysteresis in the fabricated thin-film transistors. In particular, the dual-sweep hysteresis window was significantly reduced from 2.1 V to 0.2 V, while the extracted effective trap density decreased by approximately 50%. The results demonstrate that ALD supercycle engineering provides an effective route for controlling defect characteristics and transistor operation through precise composition modulation. These findings highlight the importance of composition-dependent defect engineering for electrically stable oxide semiconductor TFTs compatible with low-temperature BEOL integration.

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