GLAD-grown TiO2/SnO2 nanowire heterostructure for enhanced fast-switching photodetection.

This study investigates a fast-switching photodetector based on heterostructure TiO₂/SnO₂ nanowire (NW), synthesized by using the GLAD-assisted e-beam evaporation technique. For performance comparison, a heterostructure TiO₂/SnO₂ thin-film (TF) device was also fabricated. Both the NW and TF heterostructure devices were synthesized on n-type silicon (n-Si) substrates, with gold (Au) as the top contact. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and chemical mapping were employed to conduct morphological and elemental analysis. Characterization of structural properties was accomplished by using X-ray diffraction (XRD). Optical measurements indicated that with two broad visible absorption peaks at 430 nm and 673 nm, the heterostructure TiO₂/SnO₂ NW sample demonstrated a 2.18-fold enhancement in ultraviolet (UV) absorption and a 1.22-fold enhancement in visible light absorption when compared to its thin-film counterpart. The heterostructure TiO₂/SnO₂ NW device demonstrated a ∼10-fold photosensitivity enhancement in comparison to the TF device. In addition, it obtained a higher detectivity of 1.193×10¹⁰ Jones and a lower noise equivalent power (NEP) of 1.114×10^-11W. Fast switching behavior was demonstrated by the current-time (I-T) characteristics, with a rise time of 0.23 s and a fall time of 0.31 s. This confirms the device's potential for high-performance photodetection applications.