Carrier dynamics of intermediate sub-bandgap transitions in ZnTeO

The incorporation of electronic states in the bandgap, with high radiative efficiency, provides a means for optical up/down conversion and for tuning the carrier lifetime of a material. Such intermediate states in highly mismatched alloys have recently received much attention due to their potential for an efficient solar energy conversion. Understanding the carrier dynamics and pathways for the charge transfer of sub-bandgap transitions is critical for understanding energy conversion processes. In this work, time-resolved photoluminescence of ZnTeO is reported, revealing electron relaxation from the conduction band to the intermediate band and the carrier transfer between intermediate states and the conduction band utilizing two time-delayed optical excitations. This work demonstrates the utility of time-resolved techniques for characterizing energy conversion mechanisms in intermediate band materials, and the ability to use intermediate states to intentionally alter carrier lifetimes in materials for applications such as ultrafast scintillation.