Fabrication of indium gallium zinc oxide phototransistors via oxide-mesh insertion for visible light detection

Abstract

We developed amorphous indium gallium zinc oxide (a-IGZO) phototransistors that could sense up to the red light region of the visible light spectrum. The vital element of the utilized technology in this study is the creation of defects within the a-IGZO thin film that serves as the channel layer of a thin film transistor (TFT) through structural engineering. The defects are induced by inserting mesh-structured titanium dioxide (m-TiO₂) layers inside the channel. The oxygen vacancies thus generated create subgap states within the band gap of a-IGZO, enabling detection of the visible light with wide wavelengths. As a result, the optimized a-IGZO phototransistor with m-TiO₂ inserted inside the channel layer exhibited a photoresponsivity of 178.66 A W⁻¹, a photosensitivity of 1.04 × 10⁵, and a detectivity of 1.25 × 10¹⁰ Jones under monochromatic red light (635 nm wavelength) illumination.