Origin of the injection-dependent emission blueshift and linewidth broadening of III-nitride light-emitting diodes

TL;DR

This paper explains the injection-dependent blueshift and linewidth broadening in III-nitride LEDs through multi-scale modeling, revealing how carrier dynamics influence spectral characteristics and suggesting design improvements for better color purity.

Contribution

It provides a first-principles explanation of spectral shifts in polar III-nitride LEDs, linking carrier dynamics to emission properties and proposing strategies to mitigate spectral broadening.

Findings

Carrier dynamics directly affect emission spectral shifts.

Designs improving carrier transport reduce blueshift and broadening.

Polar III-nitride LEDs have limited control over color purity due to carrier transport issues.

Abstract

III-nitride light-emitting diodes (LEDs) exhibit an injection-dependent emission blueshift and linewidth broadening that is severely detrimental to their color purity. Using first-principles multi-scale modelling that accurately captures the competition between polarization-charge screening, phase-space filling, and many-body plasma renormalization, we explain the current-dependent spectral characteristics of polar III-nitride LEDs fabricated with state-of-the-art quantum wells. Our analysis uncovers a fundamental connection between carrier dynamics and the injection-dependent spectral characteristics of light-emitting materials. For example, polar III-nitride LEDs offer poor control over their injection-dependent color purity due to their poor hole transport and slow carrier recombination dynamics, which forces them to operate at or near degenerate carrier densities. Designs that accelerate carrier recombination and transport and reduce the carrier density required to operate LEDs at a given current density lessen their injection-dependent wavelength shift and linewidth broadening.