Engineering of p-AlxGa1-xN Layer in AlGaN-Based UV-C LED to Improve Efficiency Droop by ~83% and IQE by ~41 %

In this simulation, we have investigated the engineering of p-Al
x
Ga
1-x
N layer to improve the internal quantum efficiency (IQE) and efficiency droop of AlGaN-based ultraviolet-C light emitting diodes. This leads to enhancement of the carrier injection and the radiative recombination (RR) rate of the proposed structure. Linear grading of p-Al
x
Ga
1-x
N layer reduces the carrier spill-off from the active region by increasing the potential barrier height for electrons (from 242.71 me V to 313.32 me V) in the conduction band. Meanwhile, it also improves the hole injection by reducing the potential barrier height for holes (from 443.7 meV to 384.7 meV) in the valence band. The reduction in the internal electric field of the multiple quantum wells (from 62.4
$\text{eV}/\mu\mathrm{m}$
to 52.9 eV /μm) confirms the reduction of quantum confined stark effect (QCSE) in the engineered sample. The reduction of QCSE and the enhancement of hole injection increases the RR rate by~10 fold for the quantum wells in the engineered sample compared to the control sample, hence increasing the IQE by ~41%. Also, the efficiency droop is improved by
$\sim$
83%. The Al-composition of p-Al
x
Ga
1-x
N layer was so adjusted that both the control and engineered samples emit at same wavelength, i.e.,~276 nm.