Enhancement of Hole Confinement by Monolayer Insertion in Asymmetric Quantum-Barrier UVB Light Emitting Diodes

We study the enhanced hole confinement by having a large bandgap AlGaN monolayer insertion (MLI) between the quantum well (QW) and the quantum barrier (QB). The numerical analysis examines the energy band alignment diagrams, using a self-consistent 6 × 6 k ·p method and, considering carrier distribution, recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates), under equilibrium and forward bias conditions. The active region is based on Al_aGa_1-aN (barrier)/Al_bGa_1-bN (MLI)/Al_cGa_1-cN (well)/Al_dGa_1-dN (barrier), where b d a c. A large bandgap AlbGa1 - bN mono layer, inserted between the QW and QB, was found to be effective in providing stronger hole confinement. With the proposed band engineering scheme, an increase of more than 30% in spatial overlap of carrier wavefunction was obtained, with a considerable increase in carrier density and direct radiative recombination rates. The single-QW-based UV-LED was designed to emit at 280 nm, which is an effective wavelength for water disinfection.