project aims at processing crystal phase quantum dots in nanowires to propose
new device designs for quantum photonic applications. This will be done using
our state of the art clean room facility.
Precise control of optical
properties of quantum devices would represent a major milestone, yet to be demonstrated,
for communication and computation technologies exploiting quantum mechanical
phenomena, such as quantum cryptography or quantum network. To realize this
technologic stride, our approach is to employ a novel concept which is control
of crystal phase switching in nanowires.
This polytypism – presence of
different crystal phases – was discovered 25 years ago when random segments of
zinc blende and wurtzite crystal structures were found in nanowires. The great
potential for applications of nanowires is hampered by the modification of
their properties related to these “defects”. Despite the widespread research
effort, this polytypism is still not yet well controlled.
Furthermore, enabling precise crystal phase control allows the
realization of tailored crystal phase quantum dot (QD) -- consisting of small
segments of ZB in WZ structure or vice versa in a nanowire – with atomically
sharp interfaces. This unique advantage compared to other QDs -- made by
changing or inserting an alloy in another host material -- would allow the
production of device with controlled optical properties and uniformity.
This makes crystal phase QDs one of the most promising candidate as
quantum bit building block.
In our team we aim to develop
these homostructures towards development of novel quantum devices using a
Metalorganic vapour phase epitaxy (MOVPE) reactor. We are actually growing InP
NWs by self catalization on Si and InP wafers. To improve crystal purity and
achieve phase switching, we are employing different strategies along with
feedbacks from electronic microscopy and optical characterization.
Goals of the project (which
may be modified according to the interests of the student)
Develop an understanding of the requirements for new
quantum information devices
Realization of quantum photonic devises through
crystal phase quantum dots
Knowledge in quantum mechanics or/and cleanroom processing would be an advantage