Enhancing Detectivity of Indium-Oxide-Based Photodetectors via Vertical Nanostructuring Through Glancing Angle Deposition

In₂O₃ vertical nanostructures (VNS) are fabricated using a glancing angle deposition (GLAD) technique upon an In₂O₃ thin film (TF) on a n-type silicon (n-Si) substrate. Analysis using high-resolution transmission electron microscopy (HRTEM) and high-resolution x-ray diffraction (HRXRD) revealed that the In₂O₃ VNS are amorphous in nature. An average ~4.5-fold enhancement in absorption was observed and a microscopic origin was proposed for observed bandgap changes for the n-Si/In₂O₃ TF/GLAD In₂O₃ VNS and bare n-Si/In₂O₃ TF samples in the visible region due to surface-related trap states or oxygen vacancies. The improvement in photodetection was attributed to the presence of a large number of surface-related trap states at the edge of metal contacts. The fabricated VNS detector possesses enhanced photosensitivity (~1.7-fold) due to an efficient photogating effect in the depletion region. A maximum detectivity of ~12.8 × 10⁷ Jones was observed for the n-Si/In₂O₃ TF/GLAD In₂O₃ VNS device, which possesses ~15.6-fold enhanced detectivity as compared to the bare n-Si/In₂O₃ TF device.