Evaluation of defects in cuprous oxide through exciton luminescence imaging

TL;DR

This study uses cryogenic hyperspectral imaging to analyze exciton luminescence in cuprous oxide crystals, revealing defect-related decay mechanisms and effects of annealing on strain and vacancy populations.

Contribution

It provides detailed imaging of exciton luminescence in Cu2O, linking defect presence and strain effects to luminescence behavior, and shows how annealing modifies defect structures.

Findings

Strain splitting observed in exciton luminescence indicates local strain variations.

Annealing reduces strain and alters vacancy populations in Cu2O crystals.

Vacancy annihilation correlates with changes in luminescence intensity.

Abstract

The various decay mechanisms of excitons in cuprous oxide (Cu2O) are highly sensitive to defects which can relax selection rules. Here we report cryogenic hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown via the floating zone method showing the samples have few defects. Some locations, however, show strain splitting of the 1s orthoexciton triplet polariton luminescence. Strain is reduced by annealing. In addition, annealing causes annihilation of oxygen and copper vacancies, which leads to a negative correlation between luminescence of unlike vacancies.