Sec-Eliminating the SARS-CoV-2 by AlGaN Based High Power Deep Ultraviolet Light Source

Abstract

The world-wide spreading of coronavirus disease (COVID-19) has greatly shaken human society, thus effective and fast-speed methods of non-daily-life-disturbance sterilization have become extremely significant. In this work, by fully benefitting from high-quality AlN template (with threading dislocation density as low as ≈6×10⁸ cm^-2) as well as outstanding deep ultraviolet (UVC-less than 280 nm) light-emitting diodes (LEDs) structure design and epitaxy optimization, high power UVC LEDs and ultra-high-power sterilization irradiation source are achieved. Moreover, for the first time, a result in which a fast and complete elimination of SARS-CoV-2 (the virus causes COVID-19) within only 1 s is achieved by the nearly whole industry-chain-covered product. These results advance the promising potential in UVC-LED disinfection particularly in the shadow of COVID-19.

Keywords: AlGaN based device; SARS‐CoV‐2; fast sterilization; ultraviolet C LED.

Figure 1

AFM image of the surface of AlN layer grown on NPSS substrate in a scanned area of a) 10 × 10 µm² (scale bar: 14 nm) and b) 2 × 2 µm² (scale bar: 0.6 nm) with an RMS roughness of about 0.09 nm. Cross‐sectional dark‐field STEM images under two‐beam conditions for AlN grown on NPSS with c) g = [0002], and d) g = $[11\overline{2}0]$. Based on the standard Burgers vector analysis using invisibility criterion g · b = 0, the screw‐type and edge‐type dislocation lines are observed in (c) and (d), respectively.

Figure 2

a) Schematic diagram of the UVC LED structure grown by MOCVD on AlN/NPSS template. b) XRD $(10\overline{1}5)$RSM of the as‐grown UVC LED wafer. The red dashed line presents the reciprocal space position which is fully strained to the AlN template (without relaxation). c) HAADF‐STEM image of the MQWs in UVC LED, the corresponding EDS mapping of d) Al and e) Ga elements and f) the EDS line scan curve is also presented to give a quantitative description of the Al composition distribution. It shows 4 periods of MQW emitting region consisting of approximately 2 nm‐thick Al_0.40Ga_0.60N wells and 5 nm‐thick Al_0.52Ga_0.48N barrier layers.

Figure 3

a) The electroluminescence demonstration of the as‐grown UVC LED wafer. The visible blue‐violet light originates from defect luminescence in the MQWs region since the UVC emission is not visible. b) The 10 × 20 mil square chips produced by UVC‐LED wafer, and interdigitated finger electrode pattern is designed to adverse the current lateral spreading. c) Demonstration of UVC LED device adopting flip‐chip packaging technology.

Figure 4

a) Output power versus current curve of a single packaged UVC LED (the electroluminescence spectrum is given in the inset). b) Demonstration of integrated sterilization light source fabricated by UVC‐LEDs (without SARS‐CoV‐2 sample). This integrated array is composed of 13 parallel connected units and each unit includes 15 UVC LEDs in series connection. c) Current dependent power density at different distances from the irradiation source. The output power density obeys an inverse‐square law as a dependence of irradiation distance, suggesting the importance of choosing a suitable working distance. Considering the working efficiency of every single LED, a working current of 1.3 A is chosen for the integrated source, in which condition each device works at 100 mA. The output power density adjacent to the array (d = 0) is 192 mW cm⁻² at 1.3 A. The working point in the virus eliminating experiment is marked by a red star (94 mW cm⁻²). d) The schematic image of the virus eliminating experiments.