  This work reports an original method for the fabrication of
Metal-Isulator-Semiconductor (MIS) structures with silicon nanocrystals (Si
NCs) based active layers embedded in the insulating SiO 2 oxide, for high
performance solar cell and photodetector applications. The Si NCs are produced
via the in situ solid-state dewetting of ultra-pure amorphous
silicon-oninsulator (a-SOI) grown by solid source molecular beam epitaxy
(SSMBE). The size and density of Si NCs are precisely tuned by varying the
deposited thickness of silicon. The morphological characterization carried out
by using atomic force microscopy (AFM) and scanning electron microscopy (SEM)
shows that the Si NCs have homogeneous size with welldefined spherical shape
and densities up to ~10 12 /cm 2 (inversely proportional to the square of
nominal a-Si thickness). The structural investigations by high resolution
transmission electron microscopy (HR-TEM) show that the ultra-small Si NCs
(with mean diameter ~7 nm) are monocrystalline and free of structural defects.
The electrical measurements performed by current versus voltage (I-V) and
photocurrent spectroscopies on the Si-NCs based MIS structures prove the
efficiency of Si NCs to enhance the electrical conduction in MIS structures and
to increase (x10 times) the photocurrent (i.e. at bias voltage V =-1 V) via the
photogeneration of additional electron-hole pairs in the MIS structures. These
results evidence that the Si NCs obtained by the combination of MBE growth and
solid-state dewetting are perfectly suitable for the development of novel high
performance optoelectronic devices compatible with the CMOS technology.
