Polariton states bound to defects in GaAs/AlAs planar microcavities

TL;DR

This study investigates polariton states bound to various defects in GaAs/AlAs microcavities, revealing how these defects create localized potential landscapes that trap polaritons with long lifetimes, impacting their spatial dynamics.

Contribution

It provides detailed characterization of defect-induced polariton bound states and their potential landscape in GaAs/AlAs microcavities, highlighting the effects of specific defect types.

Findings

Defects induce local potential modulations up to 15 meV.

Bound polariton states exhibit long lifetimes around 10 ps.

Defects create spatially smooth confinement potentials.

Abstract

We report on polariton states bound to defects in planar GaAs/AlAs microcavities grown by molecular beam epitaxy. The defect types relevant for the spatial polariton dynamics in these structures are cross-hatch misfit dislocations, and point-like defects extended over several micrometers. We attribute the latter defects to Ga droplets emitted occasionally by the Ga cell during the growth. These defects, also known as oval defects, result in a dome-like local modulation of surface, which is translated into the cavity structure and leads to a lateral modulation of the cavity polariton energy of up to 15\,meV. The resulting spatially localized potential landscape for the in-plane polariton motion creates a series of bound states. These states were characterized by spectrally resolved transmission imaging in real and reciprocal space, and reveal the spatial potential created by the defects. Interestingly, the defect states exhibit long lifetimes in the 10ps range, which we attribute to a spatially smooth confinement potential.