Dual-Band Ultraviolet Photodetection via a Single SiC/SiO₂/Ga₂O₃ Core-Shell-Satellite Nanowire Heterojunction

Ultraviolet (UV) photodetectors play a critical role in a wide range of applications, including environmental monitoring and optical communication systems. However, a significant challenge remains in enabling band-selective and adaptive detection across distinct UV spectral regions─specifically UVA (320-400 nm) and UVC (200-280 nm)─within a single, compact device. To address this limitation, we present a novel dual-band UV photodetector based on a single SiC/SiO₂/Ga₂O₃ core-shell-satellite nanowire heterojunction. In this radial configuration, a SiC nanowire functions as the central core, an amorphous SiO₂ layer is formed via in situ thermal oxidation, and gallium oxide (Ga₂O₃) nanoparticles serve as satellite sensitizers. By precisely engineering the energy band alignment of the heterostructure, the device achieves selective detection of UVA and UVC radiation. Under 365 nm (UVA) illumination, photon absorption and photocurrent generation occur exclusively in the SiC core (bandgap ∼2.4 eV). In contrast, upon exposure to 254 nm (UVC) irradiation, a synergistic photoresponse is activated between the Ga₂O₃ satellites (bandgap ∼4.7 eV) and the SiC core, resulting in significantly enhanced performance: a responsivity of 1547 A/W, an external quantum efficiency of 5.3 × 10⁵%, and rapid response and recovery times of 98 and 93 ms, respectively. This superior UVC performance is attributed to efficient carrier separation and transport within the heterojunction, enabled by the intermediate SiO₂ layer, which serves dual roles as a passivation layer and a carrier tunneling medium. This study not only introduces a novel material framework for advanced UV photodetectors but also offers valuable insights into the photophysical mechanisms underlying complex heterojunction systems, thereby contributing to the advancement of adaptive and multifunctional optoelectronic technologies.