Study on Amorphous In–Ga–Zn–O Phototransistors by Plasma‐Based Low‐Temperature Annealing Process

The plasma‐based low‐temperature annealing process used in this study can effectively improve defects in the active layer of transistor devices, thus exploring its feasibility for application on flexible substrates with lower heat resistance. In this work, low‐temperature processing is defined as any fabrication or postannealing step conducted at ≤150 °C for low‐thermal‐budget compatibility; accordingly, plasma‐assisted annealing was performed at 150 °C with plasma powers of 40, 80, and 120 W to identify the optimal processing condition. Under the 80 W plasma treatment condition, the device exhibited excellent electrical properties, with an electron mobility of 6.30 cm ² /V s, an on/off current ratio of 5.0 × 10 ⁵ , a threshold voltage of 8.68 V, and a subthreshold swing of 2.04 V/dec. Negative bias stress tests demonstrated improved stability, with a threshold voltage shift of only ‒1.08 V. Regarding optical properties, the 80 W plasma‐treated device showed over a 200‐fold increase in photosensitivity compared to the untreated device, along with enhanced dynamic photoresponse characteristics. These results confirm that the plasma‐based low‐temperature annealing process effectively enhances both electrical stability and visible‐light detection performance in a‐IGZO phototransistors.