Erbium Excitation in a SiO[sub 2] : Si-nc Matrix under Pulsed Pumping

Abstract

The photoluminescence of Er3+ ions in a SiO2 matrix containing silicon nanocrystals 3.5 nm in diameter is studied under resonant and nonresonant pulsed pumping with pulses 5 ns in duration. The effective erbium excitation cross section under pulsed pumping, σeff = 8.7 × 10−17 cm2, is close to that for nanocrystals. Comparison of the erbium photoluminescence intensity obtained for a SiO2 matrix with and without nanocrystals made it possible to determine the absolute concentration of optically active nanocrystals capable of exciting erbium ions, the concentration of optically active erbium, and the average number of erbium ions excited by one nanocrystal. The study revealed that excitation transfer from one erbium ion to another is a relatively slow process, which accounts for the low efficiency of erbium ion excitation under pulsed pumping in a SiO2 matrix containing silicon nanocrystals.