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 300 K by steady-state and time-resolved photoluminescence (PL) spectrometry. The Nd-related emission at 920 nm, induced by the 4 F3/2→ 4 I9/2 shell transitions, was obtained either with a resonant excitation at 585 nm or with an indirect excitation at 325 nm via Si-nc, which act as sensitizers. A saturation of the neodymiumrelated photoluminescence intensity has been evidenced for indirect excitation thanks to silicon nanocrystals at temperatures below 100 K. 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.

Influence of rapid thermal annealing temperature on the photoluminescence of Tb ions embedded in silicon nitride films

“…Furthermore, if the excitation of Tb 3+ ions is indirect, annealing could be responsible for increase of the effective absorption cross-section of Tb 3+ ionsin such case, the concentration of optically active ions does not have to change, but the number of excited ions N Tb * should be larger due to more efficient excitation energy transfer from some donor states. Similar mechanism has been reported for Nd 3+ and Er 3+ ions embedded in SiO x matrices [30][31][32]. Nevertheless, based on the obtained results it is not possible to determine which mechanism is responsible for the increased N Tb * in our case.…”

Quantum size effects and tunable visible photoluminescence in a-Si:H/nc-Si:H superlattices

“…There is great interest in integrating opto-electronic and micro-photonic functionalities into the silicon-based platform, which has faced challenges due to the indirect bandgap nature of the silicon. For this reason allotropes of silicon and nanostructured Si have been widely investigated during the last few years as it offer an enhancement in the optical properties compared to bulk Si [1][2][3][4][5][6][7][8][9][10][11] and a pathway to obtain a direct band gap. Due to the enhancement in optical properties, nanostructured Si containing embedded Si nanocrystals is finding important new applications in nano-electronic and photonic devices including transistors, memories, and silicon based light emitting structures for optoelectronics and displays units etc [12][13][14][15].…”