Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA

MBE Growth of Self-Assembled InAs and InGaAs Quantum Dots Embedded in
Silicon Matrix
carried out at constant voltage of 1 V , while the current was measured at different
stripe distances. The I-V curve was recorded and the doping level was
calculated for dierent As 4 uxes. Fig. 5.32 shows the doping level dependence
with the BEP As 4 ux. A linear carrier concentration dependence on As 4 ux
was observed up to a doping level of 7.28 × 10 17 cm −3 for a As 4 of BEP value
3.6 × 10 −8 Torr. A new series of samples were studied by keeping the As ux
constant at 1.2 × 10 −8 Torr but with increasing the layer thickness from 100 nm
to 200 nm.
Figure 5.31: Schematic digram of the metallic stripes with dierent widths deposited
on the top of the doped Si layer, for the electrical resistivity measurements.
Resistivity measurement showed that the doping density increased by a factor
of three with increased layer thicknesses from 100 nm to 200 nm, this can be explained
by the band bending eect, which will get less with thicker layers. Hence,
the transfered electrons that occupy the region where the conduction energy E c
is below the Fermi level, and constitute an accumulation layer whose thickness
is much less than the width of the band-bending in metal n-type semiconductor
junction [15].
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