This thesis deals with electrical and optical characterization
of p+i–n+ nanowire-based photodetectors/solar
cells. I have investigated their I-V performance
and found that all of them exhibit a clear rectifying
behavior with an ideality factor around 2.2 at 300K.
used Fourier transform infrared spectroscopy to extract their
optical properties. From the spectrally resolved photocurrent
data, I conclude that the main photocurrent is generated in the
i-segment of the nanowire (NW) p-i-n junctions, with negligible
contribution from the substrate.
I also used a C-V technique to investigate the
impurity/doping profiles of the NW p+-i-n+ junction.
The technique has been widely used for investigations
of doping profiles in planar p-n junctions, in particular
with one terminal (n or p) highly doped. To verify the
accuracy of the technique, I also used a planar Schottky
sample with an already known doping profile for a test
experiment. The result is very similar to the actual data.
When we used the technique to investigate the doping
level in the NWs photodetectors grown on InP substrates,
the results show a very high capacitance above 800pF
which most likely is due to the influence of the parasitic
capacitance from the insulating layer of SiO2. Thus,
a new sample design is required to investigate the
doping profiles of NWs.
2014. , 41 p.
IR photodetectors, electrical characteristics, optical characteristics, nanophotonics, InP, nanowires.