Size-controlled Si nanocrystals for photonic and electronic applications

M. Zacharias, J. Heitmann, L. Yi, R. Scholz, and U. Gösele
MPI of Microstructure Physics, Weinberg 2, 06112 Halle

We present here a new approach for fabrication of ordered Si quantum
dots which is fully compatible with normal Si technology.[1] The
preparation of SiO/SiO[2] superlattices represents a simple and
efficient method for fabricating highly luminescent Si nanocrystals
and allows independent control of size, size distribution, and
density. We can arrange the Si nanocrystals in a specific depth and
for a specific number of layers and with a specific density. The
density of the Si nanocrystals is in the range of 10¹9/cm3. TEM and
XRD investigations confirm control of the upper limit of the
nanocrystal size down to around 2.0 nm with a size distribution of ą
0.5 nm. We report TEM images showing early states of phase separation
of SiO/SiO[2] superlattice combined with IR and PL investigation.
Photoluminescence experiments show a size-dependent blue shift of the
luminescence from 950 to 750 nm and a luminescence intensity
comparable to porous Si. Temperature and power dependence of the
luminescence intensity will be reported. The nearly size-independent
PL intensity observed in our SiO/SiO[2] superlattices indicates the
accomplishment of an independent control of crystal size and number.

[1] M. Zacharias, J. Heitmann, R. Scholz, and M. Schmidt, Appl. Phys.
Lett. 80 ( 2002) 661.

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1. Electronic structure and chemical environment of Si nanoclusters embedded in a SiO₂ matrix.