title: Efficiency Drop in Green InGaN/GaN Light Emitting Diodes: The Role of Random Alloy Fluctuations.
abstract: White light emitting diodes (LEDs) based on III-nitride InGaN/GaN quantum wells currently offer the highest overall efficiency for solid state lighting applications. Although current phosphor-converted white LEDs have high electricity-to-light conversion efficiencies, it has been recently pointed out that the full potential of solid state lighting could be exploited only by color mixing approaches without employing phosphor-based wavelength conversion. Such an approach requires direct emitting LEDs of different colors, including, in particular, the green-yellow range of the visible spectrum. This range, however, suffers from a systematic drop in efficiency, known as the "green gap," whose physical origin has not been understood completely so far. In this work, we show by atomistic simulations that a consistent part of the green gap in c-plane InGaN/GaN-based light emitting diodes may be attributed to a decrease in the radiative recombination coefficient with increasing indium content due to random fluctuations of the indium concentration naturally present in any InGaN alloy.
authors.affiliation: Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Matthias
authors.initials: M
authors.lastname: Auf der Maur
authors.affiliation: CNR-ISMN, via Salaria Km 29.300, 00017 Monterotondo, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Pecchia
authors.affiliation: Bremen Center for Computational Materials Science, University of Bremen, 28359 Bremen, Germany.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Penazzi
authors.affiliation: Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Walter
authors.initials: W
authors.lastname: Rodrigues
authors.affiliation: Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Di Carlo