Construction of photoconductivity measurement system as functions of excitation wavelength and temperature: application to Eu2+-activated phosphors

Takayuki Nakanishi; Setsuhisa Tanabe

doi:10.1117/12.840110

25 February 2010 Construction of photoconductivity measurement system as functions of excitation wavelength and temperature: application to Eu²⁺-activated phosphors

Takayuki Nakanishi, Setsuhisa Tanabe

Author Affiliations +

Proceedings Volume 7598, Optical Components and Materials VII; 759809 (2010) https://doi.org/10.1117/12.840110
Event: SPIE OPTO, 2010, San Francisco, California, United States

Abstract

In order to understand the thermal quenching of rare-earth doped phosphors, the clarification of electronic energy structure of excited states is an important step. As an experimental approach, the photoconductivity measurement of the phosphor is one of the effective methods to clarify the direct interaction of the excited electron (hole) and conduction- (valence-) band. In this study, we constructed an automatic measurement system of photoconductivity in inorganic phosphors. The wavelength- and temperature- dependence of the photocurrent in a Eu²⁺: SrAl₂O₄ phosphor was measured by using this system. Excitation wavelength dependence of photocurrent showed a similar profile to the PL-excitation spectrum of Eu²⁺. The result clearly indicates interaction of 5d level of Eu²⁺ with the conduction band. The activation energy of the photocurrent was evaluated from its temperature dependence for each wavelength. It decreased with wavelength from 490nm to 400nm, and became constant (~20 meV) below 400 nm. The ground state of Eu²⁺ (⁸S_7/2) was estimated to be 3.1 eV below the bottom of the conduction band.

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Takayuki Nakanishi and Setsuhisa Tanabe "Construction of photoconductivity measurement system as functions of excitation wavelength and temperature: application to Eu²⁺-activated phosphors", Proc. SPIE 7598, Optical Components and Materials VII, 759809 (25 February 2010); https://doi.org/10.1117/12.840110

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