Exciton decay in Cu2O at high density and low temperature: Auger recombination, spin–flip scattering, and molecule formation

In this paper, we examine the relative importance of three density-dependent decay mechanisms for excitons in cuprous oxide (Cu2O). Rate-equation models including Auger recombination (A), spin–flip scattering (B) and capture into short-lived biexcitons (C) are compared to photoluminescence data for a crystal temperature of 2 K. Process B—converting two orthoexcitons into two paraexcitons by exchanging electrons and holes—leaves the total exciton number unchanged and is inconsistent with the late-time data. In processes A and C, paraexcitons re-generate high energy excitons in agreement with the late-time data; however, the existing theory of Auger recombination seems to eliminate process A, leaving molecule formation as the dominant process.