Effect of graded Al composition in w-shaped quantum wells and Δ-shaped quantum barriers on performance of AlGaN based UV-C light emitting diodes

Abstract

In this paper, we theoretically investigate the effect of geometry of QWs and QBs on the optical performance of AlGaN based UV-C LEDs. It is observed that the graded Al composition in w-shaped QW, and Δ-shaped QB enhances the radiative recombinations while reducing polarization in the active zone. The proposed novel configuration concurrently improves the hole injection efficiency and reduces the electron seepage into the p-region, which increases the rate of radiative recombination in the active zone. In contrast to the reference structure's IQE and efficiency droop (31% and 11%), the IQE and efficiency droop of proposed structure has improved to 62% and 3%, respectively, at 200 A/cm2 current density. The improvement in the IQE is attributable to the modified structure's enhancement of the carrier waveform overlap in the active zone from 18% to 39%.