Ultraviolet (UV) germicidal irradiation uses high-power 254-nm radiation from low-pressure mercury discharge lamps to kill or inactivate viral, bacterial, and fungal species. Since UV germicidal irradiation effectiveness depends primarily on the UV dose delivered to the microorganisms, it is essential to monitor the power emitted from the source by using appropriate UV-light detectors. We report on preliminary aging tests performed on high signal-to-noise ratio 4H-SiC Schottky photodiodes under high intensity mercury lamp irradiation (10 mW/cm2).