Light Extraction Efficiency Enhancement of Deep-Ultraviolet Light-Emitting Diodes with Nanostructured Silica Glass

We proposed a novel method through introducing antireflective nanostructures on the surface of silica glass in the packaging process to enhance the light extraction efficiency (LEE) of deep-ultraviolet light-emitting diodes (DUV-LEDs). Optical simulations were conducted by rigorous coupled-waved analysis (RCWA) method, and the effect of geometry and dimension of the nanostructures on the transmittance improvement of the silica glass in a UV spectral range was investigated. By utilizing moth-eye nanostructures with feature sizes of 100 nm, the average reflectance of 0.44 % is achieved in the UV range. The nanostructures were fabricated by rapid thermal annealing and additional dry etching. The experimental results demonstrate that the LEE of DUV-LEDs packaged by the dual-side nanostructured glass increases by 8.6 % compared with that the flat glass packaged DUV-LEDs at driving current of 50 mA.