book of abstracts - IM2NP

A B S T R A C T S TUESDAY, JUNE 29 N A N O S E A 2 0 1 0
3 – Conclusion
For potential devices it is important that island properties do not vary at all across the fields. In this work we
will show how by carefully adjusting the growth parameters on fields as small as 200x200 µm2 it is feasible
to obtain a highly uniform quantum dot size distribution across the entire field, including the border regions.
9H50-10H10
Characteristic interaction distance between Si nanodots and Er3+ ions in welldefined
multilayer films.
Ying-Wei Lu1, M. Christian Petersen1, J. Lundsgaard Hansen,1 A. Nylandsted
Larsen1, R. V. Skougaard Jensen2, T. Garm Pedersen2, K. Pedersen2 (1. Department of
Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark; 2. Department of Physics and
Nanotechnology, Aalborg University, DK-9220 Aalborg Ø, Denmark) ylu@phys.au.dk, mcp@phys.au.dk,
johnlh@phys.au.dk, anl@phys.au.dk rj@nano.aau.dk, tgp@nano.aau.dk, kp@nano.aau.dk
1 – Introduction
Er3+ photoluminescence (PL) sensitized by amorphous or crystalline Si nanodots has attracted intensive
attention since Si nanodots can enhance Er3+ emission due to interaction between carriers in Si nanodots and
Er3+ ions. However, the nature of the sensitizing role played by the Si nanodots is still being debated.
Several groups have studied the characteristic interaction distance between Si nanodots and Er3+ ions. In
these studies, however, the films were annealed at high temperatures which might result in Er diffusion, and
accordingly, induce a distribution in interaction distance due to ill-defined microstructures. Therefore, low
temperature annealed films with well-defined microstructure are better candidates for the characterization of
the interaction distance since Er diffusion can be completely avoided.
2 – Abstract
10 layers each consisting of a-Si/SiO2:Er/SiO2 sublayers were deposited on p-type, (001) Si wafers by rfmagnetron
sputtering without substrate heating. The thickness of the a-Si sublayers were fixed at about 3 nm.
The thickness of the SiO2:Er and pure SiO2 sublayers were varied such that the SiO2:Er sublayer thickness
increased from 0 to 5 nm, while the pure SiO2 sublayer thickness decreased accordingly to keep the
thickness of the total SiO2 layer fixed at 15 nm. After deposition, all films were annealed at 500 °C for 1 h in
95% N2 + 5% H2 and at 1100 °C for 1 h in pure N2, respectively. Secondary Ion Mass Spectrometry (SIMS)
profiles indicate that Er diffusion takes place in the films annealed at high temperature but not in those
annealed at low temperature. Moreover, PL measurements show that different characteristicinteraction
distances are extracted from the films annealed at different temperatures. Transmission electron microscopy
(TEM) and time-resolved PL spectroscopy have been employed to characterize the relationship between the
well- and ill-defined microstructures, and the different interaction models.
3 – Conclusion
The present investigation demonstrates that the characteristic interaction distance between Si nanodots and
Er3+ ions strongly depends on the annealing temperature of the films. At high annealing temperature the Er
starts to diffuse within the SiO2 layer making it impossible to operate with one interaction distance.
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