Far ultraviolet C (UVC) light sources have the potential for numerous applications ranging from sterilization, purification, sensing, deodorization, surface modification, and so on. In particular, a short wavelength of far UVC is effective at sterilizing viruses and bacteria by minimizing damage to mammalian skin. Recently, many researchers are devoting materials and alternative light sources to overcome low efficiency, small light-emitting area, UV absorption, and complicated manufacturing processes of far UVC generation. Here, the sapphire wafer is evaluated for far UVC light generation using electron beam irradiation with carbon nanotube (CNT) emitters. A CNT-based cold cathode electron beam (C-beam) that emits electrons and accelerated onto κ-Al2O3 of the sapphire wafer was used as an excitation source to demonstrate high-power far UVC light generation. High-efficiency 226 nm far UVC is made with a power conversion efficiency of 0.87% and a light-emitting area of 960 mm2. Far UVC generation depends on the input power and the crystallinity of sapphire wafers.
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