Direct hole and delayed electron capture on a picosecond timescale by Eu2+ centers in CaGa2S4 monitored by synchroscan with horizontal blanking

Direct hole and delayed electron capture on a picosecond timescale by Eu2+ centers in CaGa2S4 monitored by synchroscan with horizontal blanking

Louwers, D.J.
Takizawa, T.
Hidaka, C.
Van der Kolk, E.

Applied Sciences

RRR/Radiation, Radionuclides and Reactors

2012-05-04

A Eu2+ concentration and temperature dependent energy transfer study from the host lattice to Eu2+ luminescence centers in Ca(1–x)EuxGa2S4 (x = 0.001 to 0.05) was performed with a special streak camera that combines the high timing resolution of a conventional synchroscan operation (<2 ps) with the ability to study long lived states (10?ns???1 ms) typical for rare earth and transition metal ions. Two transfer mechanisms from the CaGa2S4 host lattice to the Eu2+ ions were identified. A fast transfer process (<4 ps) is interpreted as sequential hole-electron capture by the Eu2+ ions, and slower process (>1 ns) is interpreted as the sequential capture of a hole and an electron by Eu2+ but with the electron first entering an intermediate state trapped near Eu3+. Energy transfer via a self-trapped excitonic (STE) state is unlikely because of the absence of an anti-correlation between the STE decay-time and the Eu2+ rise-time as well as between the STE emission intensity and the Eu2+ intensity. All rise-time spectra were successfully fitted with a model representing the above transfer mechanisms.

calcium compounds
electron capture
electron-hole recombination
excitons
gallium compounds
high-speed optical techniques
hole traps
photoluminescence

http://resolver.tudelft.nl/uuid:8e6bd983-9a4a-4e28-b847-bf5c55da4677

https://doi.org/10.1063/1.4709757

American Institute of Physics

0021-8979

http://jap.aip.org/resource/1/japiau/v111/i9/p093709_s1

Journal of Applied Physics, 111 (9), 2012

Institutional Repository

journal article

© 2012 The Author(s)
American Institute of Physics