Low-temperature photoluminescence properties of Nd-doped silicon oxide thin films containing silicon nanocrystals

Abstract

The luminescence properties of neodymium-doped silicon oxide thin films containing silicon nanocrystals (Si-nc) were studied as a function of temperature from 10 to 300K by steady-state and time-resolved photoluminescence (PL) spectrometry. The Nd-related emission at 920nm, induced by the 4F3/2→4I9/2 shell transitions, was obtained either with a resonant excitation at 585nm or with an indirect excitation at 325nm via Si-nc, which act as sensitizers. A saturation of the neodymium-related photoluminescence intensity has been evidenced for indirect excitation thanks to silicon nanocrystals at temperatures below 100K. According to the Förster model of energy transfer, this saturation is explained by a decrease of the coupling efficiency between Si-nc and rare earth ions at low temperatures, induced by the increase of the silicon nanocrystals lifetime at low temperatures.