Monolithic spectrally tunable UVA/UVB/UVC AlGaN-based UV-LEDs via p-type trenches

Currently, a single AlGaN-based ultraviolet light-emitting diode (LED) can only emit ultraviolet light in a single wavelength band. To meet the demands of multi-band applications, it is typically necessary to integrate multiple chips emitting at different bands, which significantly increases the system cost. To address this bottleneck, this work proposes an epitaxial structure designed to achieve multi-band emission on a single chip. The epitaxial structure contains multiple quantum wells (MQWs) in three bands: UVA, UVB, and UVC. P-type trenches are formed by etching the epitaxial structure down to different quantum well layers. At these trenches, a p-type layer is grown by selective area growth to achieve efficient hole injection. Numerical simulations show that, compared with the device without p-type trenches, extending the p-type trench into the UVC quantum well increases the hole concentration in that well by 79.88%. Furthermore, by adjusting the etching depth, the emission ratios of the three ultraviolet light bands can be controlled. Specifically, compared with the device without p-type trenches, extending the trench to the UVC quantum well changes the spectral emission ratio of UVA, UVB, and UVC from 60.01%, 28.71%, and 11.28% to 44.30%, 31.52%, and 24.18%.