Design of InGaN/AlInGaN superlattices for white-light device applications

Major developments in wide-gap III-V nitride semiconductors have recently led to the development of LEDs, where the relative intensity of the primary colors in heterostructured diodes can be adjusted to yield white light. Most of the work in III-nitrides, so far, has been done for hexagonal (wurtzite) structures, but research efforts towards a more complete understanding of the cubic (zincblende) nitride-derived heterostructures have increased recently. In particular, with fast and important advances on material processing technology. The AlInGaN quaternary alloy exhibits interesting features, such as higher emission intensity than the ternary AlGaN alloy for certain Al compositions. In addition, it is possible to reach the near ultraviolet (UV) region allowing to better adjustment of white-light emission by mixing different emission wavelengths with adequate intensities. In this work, we perform photoluminescence (PL) and electroluminescence spectra calculations of cubic InGaN/AlInGaN superlattices by using the k·p theory within the framework of the effective mass approximation. The calculations are carried out by solving the 8×8 Kane Hamiltonian. In our calculations, strain effects due to lattice mismatch and the split-off hole band are taken into account. Theoretical PL spectra of these systems are shown and we discuss the effects imposed by Al molar fraction, superlattice composition and structure on the white-light emission properties of the system.