The Influence of Indium Component on the Preparation of a-IGZO Metal-Semiconductor-Metal Ultraviolet Photodetector by Sol–Gel Method

In this study, the indium (In) composition in amorphous indium gallium zinc oxide (a-IGZO) thin films was systematically varied from 33% to 84% using a sol–gel process. Subsequently, aluminum/IGZO/aluminum (Al/IGZO/Al) metal–semiconductor–metal (MSM) UV photodetectors were fabricated to investigate the influence of composition on the structural, optical, and photoelectric properties. The results indicate that all films maintain an amorphous structure despite the increasing In content, while the ratio of oxygen vacancies, Ovac/(M-O + Ovac), rises from 36% to 52%. Concurrently, the optical bandgap decreases from 2.92 eV to 2.32 eV. Under a bias of 20 V, the dark current increases from 2.11 × 10−9 A to 1.90 × 10−5 A as the In content rises. When illuminated by a 360 nm LED with a power density of 8.6 mW/cm2, the device with 60% In exhibits a photocurrent-to-dark-current ratio of approximately 104, a responsivity of 19.45 A/W, and a specific detectivity of 8.19 × 1012 Jones. The response time and recovery time of this device are 39.8 s and 577.4 s, respectively. These findings reveal a competitive relationship between enhanced optical absorption and defect generation induced by In composition, providing valuable guidance for the performance optimization of a-IGZO UV photodetectors through compositional engineering.