# Exciton-exciton annihilation in hBN

## TL;DR

This study demonstrates exciton-exciton annihilation in bulk hBN at low temperature, estimating a high EEA rate and suggesting its significant role in luminescence quenching in low-dimensional BN materials.

## Contribution

First measurement of EEA rate in bulk hBN, revealing the highest reported value for a bulk semiconductor at low temperature.

## Key findings

- EEA rate of 2×10⁻⁶ cm³·s⁻¹ at 10 K
- EEA likely contributes to luminescence quenching in low-dimensional BN
- EEA is stronger in nanotubes or atomic layers

## Abstract

Known as a prominent recombination path at high excitation densities, exciton-exciton annihilation (EEA) is evidenced in bulk hexagonal boron nitride (hBN) by cathodoluminescence at low temperature. Thanks to a careful tune of the the exciton density by varying either the current or the focus of the incident electron beam, we could estimate an EEA rate of 2$\times$10$^{-6}$ cm$^{3}$.s$^{-1}$ at $T=10$ K, the highest reported so far for a bulk semiconductor. Expected to be even stronger in nanotubes or atomic layers, EEA probablly contributes to the luminescence quenching observed in low-dimensionality BN materials.