Design of Phosphor-Free Single-Chip White Light-Emitting Diodes Using InAlGaN Irregular Multiple Quantum Well Structures

A novel approach for the design of phosphor-free single-chip white light-emitting diodes (LEDs) is proposed by employing InAlGaN irregular multiple quantum well (IMQW) structures. The electronic and optical properties of the designed InAlGaN IMQWs are analyzed in detail by fully considering the effects of strain, well-coupling, valence band-mixing, and quasi-bound states using the effective-mass Hamiltonian deduced from k・p theory. For comparison, three different types of InAlGaN IMQW structures with ultra-wide band spontaneous emission spectra are analyzed, and the results show that phosphor-free single-chip white light LEDs with more than 200nm emission band can be obtained using properly designed InAlGaN IMQW structures.