Nanopatterned sapphire substrate to enhance the efficiency of AlGaN-based UVC light source tube with CNT electron-beam

Abstract

The short wavelength of far ultraviolet C (UVC) light sources is effective for various applications that include sterilizing bacteria and viruses, water purification, and sensing. Here, a triode structure UVC light source tube operating at ∼270 nm using a carbon nanotube (CNT) electron emitter as an excitation source is achieved to overcome the known issues with a conventional UVC-LED. The cathodoluminescence (CL) layer-based AlGaN MQW heterostructure is evaluated for UVC light emission. For comparison, the AlGaN-based MQW heterostructure was grown on a conventional sapphire substrate (CSS) and a nanopatterned sapphire substrate (NPSS). The NPSS efficiently enhanced the emission efficiency of UVC light, compared to that grown on a CSS. The output power of the UVC light source tube with AlGaN MQWs grown on NPSS was 2.33 times higher than that grown on CSS. Correspondingly, a high-power efficiency of 1.87% was demonstrated through a 2 inch light-emitting area with a low consumption energy of 18 W (anode voltage 9 kV; anode current 2 mA).