Interplay of structural design and interaction processes in tunnel-injection semiconductor lasers

TL;DR

This paper provides a theoretical analysis of tunnel-injection processes in quantum-dot lasers, revealing how energy alignment and scattering mechanisms influence carrier injection efficiency, which can improve laser performance.

Contribution

It introduces a detailed theoretical model of carrier dynamics in tunnel-injection quantum-dot lasers, highlighting the impact of state alignment and scattering on injection efficiency.

Findings

LO-phonon resonance weakly affects injection rate

Quantum-dot and quantum-well state alignment influences hybridization

Carrier injection is governed by phonon-mediated and Coulomb scattering

Abstract

Tunnel-injection lasers promise various advantages in comparison to conventional laser designs. In this paper, we present a theoretical analysis for the physics of the tunnel-injection process in quantum-dot based laser devices. We describe the carrier dynamics in terms of scattering between states of the coupled system consisting of injector quantum-well, tunnel-barrier, and quantum-dots. Our analysis demonstrates how current quantum-dot based lasers can benefit from the tunnel-injection design. We find that the often assumed LO-phonon resonance condition for the level alignment only weakly influences the injection rate of carriers into the quantum-dot states. On the other hand, our investigations show that the energetic alignment of quantum-dot and quantum-well states modifies the injection efficiency, as it controls the hybridization strength. Our description of tunneling includes the phonon-mediated and the Coulomb scattering contributions and is based on material realistic electronic structure calculations.