Excitation efficiency and limitations of the luminescence of Eu3+ ions in GaN

TL;DR

This study investigates the excitation mechanisms and efficiency limitations of Eu3+ ions doped in GaN, revealing key factors affecting luminescence output and potential for efficient light emission.

Contribution

It provides new insights into the excitation efficiency limits and the role of excitation conditions in Eu3+-doped GaN luminescence.

Findings

External luminescence quantum efficiency reached 46% at low temperatures.

Carrier traps limit Eu3+ excitation at low pump fluences.

High excitation cross-section Eu3+ sites are limited, affecting efficiency.

Abstract

The excitation efficiency and external luminescence quantum efficiency of trivalent Eu3+ ions doped into gallium nitride (GaN) was studied under optical and electrical excitation. For small pump fluences it was found that the excitation of Eu3+ ions is limited by an efficient carrier trap that competes in the energy transfer from the host material. For large pump fluences the limited number of high-efficiency Eu3+ sites, and the small excitation cross-section of the majority Eu3+ site, limit the quantum efficiency. At low temperatures under optimal excitation conditions, the external luminescence quantum efficiency reached a value of 46%. These results show the high potential for this material as an efficient light emitter, and demonstrates the importance of the excitation conditions on the light output efficiency.