Cascaded deep UV and blue LEDs with integrated GaN tunnel junction

The growing demand for reliable sterilization methods, coupled with the spread of COVID-19, has driven exploration of the use of deep ultraviolet (DUV) radiation for disinfection purposes. Given that exposure to highly energetic DUV radiation poses a significant risk to the eyes and skin, portable sterilizing equipment must emit both visible and DUV wavelengths to simultaneously indicate its operation and perform sterilize. In this paper, we explore the effect of the tunnel junction in cascading visible and ultraviolet active regions instead of the cascade region. In our reference device, two Al_xGa_1−xN layers are used to facilitate carrier movement from one active region to another, but this does not work effectively due to the presence of greater barriers for holes and electrons. Introducing a tunnel junction reduces these barriers; consequently, the radiative recombination rate is increased by a factor of 2.2, while the emission intensity is increased by factors of 1.3 and 2.7 for ultraviolet and blue wavelengths, respectively.