Vacancy Relaxation in Cuprous Oxide (Cu$_{2-x}$O$_{1-y}$)

TL;DR

This study investigates vacancy relaxation in Cu$_{2-x}$O, revealing how copper and oxygen vacancies produce phonons, with their properties influenced by synthesis and temperature, using time-resolved luminescence and transient absorption techniques.

Contribution

It provides new insights into vacancy relaxation mechanisms in Cu$_{2-x}$O$, including phonon emission characteristics and the differing behaviors of copper and oxygen vacancies.

Findings

Copper vacancy luminescence lifetime is ~25 times longer at low temperature.

Both vacancy types emit phonons following a Poissonian distribution.

Oxygen vacancies absorb light transiently, indicating their role as traps.

Abstract

Phonons are produced when an excited vacancy in cuprous oxide (Cu$_2$O) relaxes. Time resolved luminescence was used to find the excited copper vacancy (acceptor) and oxygen vacancy (donor) trap levels and lifetimes. It was also used to determine the typical energy and number of phonons in the phonon pulses emitted by vacancies. The vacancy properties of cuprous oxide are controlled by several synthesis parameters and by the temperature. We directly demonstrate the absorption of light by oxygen vacancies with transient absorption. Copper and oxygen vacancies behave differently, in part because the two kinds of traps capture carriers from different states. For example, the copper vacancy luminescence lifetime is around 25 times greater at low temperature. However, both kinds of vacancy luminescence are consistent with a Poissonian multiple phonon emission model.