Energy transfer processes in Er-doped SiO2 sensitized with Si nanocrystals

TL;DR

This study investigates energy transfer mechanisms in Er-doped SiO2 with Si nanocrystals, revealing detailed insights into light emission processes and addressing the optical activity loss of Er ions upon sensitization.

Contribution

It provides a comprehensive microscopic model of energy transfer in Er-doped SiO2 with Si nanocrystals, clarifying the sensitization process and limitations.

Findings

Identified emission bands from Si NCs and Er3+ ions

Developed a microscopic energy transfer model

Clarified the loss of Er optical activity

Abstract

We present a high-resolution photoluminescence study of Er-doped SiO2 sensitized with Si nanocrystals (Si NCs). Emission bands originating from recombination of excitons confined in Si NCs and of internal transitions within the 4f-electron core of Er3+ ions, and a band centered at lambda = 1200nm have been identified. Their kinetics have been investigated in detail. Based on these measurements, we present a comprehensive model for energy transfer mechanisms responsible for light generation in this system. A unique picture of energy flow between subsystems of Er3+ and Si NCs is developed, yielding truly microscopic information on the sensitization effect and its limitations. In particular, we show that most of the Er3+ ions available in the system are participating in the energy exchange. The long standing problem of apparent loss of optical activity of majority of Er dopants upon sensitization with Si NCs is clarified and assigned to appearance of a very efficient energy exchange mechanism between Si NCs and Er3+ ions. Application potential of SiO2:Er sensitized by Si NCs is discussed in view of the newly acquired microscopic insight.