Plasmonic ultraviolet (UV) photodetectors have witnessed ongoing and tremendous enhancements in quantum efficiency and responsivity. Here, we go beyond regular plasmonic detectors by using periodic arrays of fractal aluminum nanostructures as Cayley trees deposited on a Ga<sub>2</sub>O<sub>3</sub> substrate to generate photocurrent. We show that the proposed aluminum Cayley trees are able to support and intensify strong broad plasmon resonant modes across the UV to the visible spectrum. It is shown that the Cayley trees can be tailored to facilitate strong absorption at high energies (short wavelengths), resulting formation of hot carriers. Having perfect compatibility to operate at the UV spectrum, fractal aluminum structures and Ga<sub>2</sub>O<sub>3</sub> substrate help to increase the produced photocurrent remarkably. Presence of Ga<sub>2</sub>O<sub>3</sub> layer blue-shifts the peak of absorption to higher energies and helps to generate hot carriers at deeper UV wavelengths.