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البحوث المنشورة

البحث (1):

عنوان البحث:

Low Leakage-Current InAsSb
Nanowire Photodetectors on Silicon

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تاريخ النشر:

  16/12/2015

موجز عن البحث:

Axially doped p−i−n
InAs0.93Sb0.07 nanowire arrays have been grown on Si substrates and
fabricated into photodetectors for shortwave infrared detection. The devices
exhibit a leakage current density around 2 mA/cm2 and a 20% cutoff of 2.3 μm
at 300 K. This record low leakage current density for InAsSb based devices
demonstrates the suitability of nanowires for the integration of III−V
semiconductors with silicon technology.

البحث (2): 

عنوان البحث:

Room-Temperature Mid-Infrared
Emission from Faceted InAsSb Multi Quantum Wells Embedded in InAs Nanowires 

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تاريخ النشر:

 30/11/2017

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There is considerable interest
in the development of InAsSb-based nanowires for infrared photonics due to
their high tunability across the infrared spectral range, high mobility, and
integration with silicon electronics. However, optical emission is currently
limited to low temperatures due to strong nonradiative Auger and surface
recombination. Here, we present a new structure based on conical type II
InAsSb/InAs multiquantum wells within InAs nanowires which exhibit bright
mid-infrared photoluminescence up to room temperature. The nanowires are
grown by catalyst-free selective area epitaxy on silicon. This unique
geometry confines the electron−hole recombination to within the quantum
wells which alleviates the problems associated with recombination via surface
states, while the quantum confinement of carriers increases the radiative
recombination rate and suppresses Auger recombination. This demonstration
will pave the way for the development of new integrated quantum light sources
operating in the technologically important mid-infrared spectral range.

المؤتمرات العلمية:

المؤتمر (1):

عنوان المؤتمر:

Nanowires
workshop

تاريخ الإنعقاد:

26/10/2015

مكان
الإنعقاد:

Barcelona, Spain

طبيعة المشاركة:

Poster presentation

عنوان المشاركة:

Catalyst-free
selective area MBE growth of InAsSb nanowires on a Si patterned substrate

ملخص المشاركة:

Semiconductor nanowires have
attracted much attention over the past few years as a key building block for
nanodevices. By controlling the growth on a nanometre scale we can achieve
unique opportunities for combining materials, manipulating properties, and
designing novel devices1 . In this study, we have developed a site controlled
InAsSb nanowires (NWs) grown on Patterened Si (111) substrate using selective
area Molecular Beam Epitaxy (MBE) growth and defined by electron beam
lithography (EBL). This method is very promising to form a wire arrays
without the use of Aucatalyst or metal droplet that can limit the performance
of the grown devices2 . High quality vertically aligned NWs were obtained
with highly uniform diameters along the growth direction as confirmed by
Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM),
X-Ray and Photoluminescence (PL) analysis. The NWs exhibited phase pure- zinc
blende crystal structure. PL spectroscopy at 4K revealed a peak emission
consisting of emission from the InAs section at 0.435 eV and more intense
emission from the InAsSb section at 0.370 eV(see figure 1(b)). Photodetectors
fabricated from doped p-i-n nanowires have shown a dark current density more
than an order of magnitude lowers than state of the art InAs devices. These
results show a promising route for integration of well- aligned and high
quality MBE- grown InAsSb NWs with silicon technology for next generation
devices3 .

المؤتمر (2):

عنوان المؤتمر:

Nanotech Dubai 2016

تاريخ الإنعقاد:

05/12/2016

مكان
الإنعقاد:

Dubai.UAE

طبيعة المشاركة:

Paper presentation

عنوان المشاركة:

MBE Grown InAsSb Nanowires
Photodetectors

ملخص المشاركة:

InAsSb Semiconductor nanowires
(NWs) have been considered as promising materials for the fabrication of
mid-infrared photodetectors, due to their narrow band gap and the high
carrier mobility1 . In addition when grown on low cost Si substrates they
offer the potential for integration with silicon electronics technology and
increased functionality. The growth of InAsSb NWs has been reported using
different growth techniques, such as Au –catalyzed and more recently by
catalyst-free selective area Metal Organic Chemical Vapor Deposition2 . In
this work, we report on the growth of InAsSb NWs on Si substrates using
catalyst freeselective area Molecular Beam Epitaxy growth. Highly uniform
nanowires were obtained with a strong photoluminescence emission from the
wires. X-ray measurments were used to determine the incorporated Sb fraction
in the wires, these results were in good agreement with the PL emission,
which also confirmed the quality of the grown wires. Growing uniform wires by
using free catalyst growth can be used as an effective method compared to
metal catalyst growth, as the gold forms trap states in silicon and can limit
the efficiency of the fabricated photodetectors. However, while maintaining
high crystal quality, nanowires containing a p-i-n junction were grown in a
square array of a 200 nm pitch. The structure of the nanowires is formed by a
first region of doped InAsfollowed by a second layer consist of InAsSb
(p-doped, undoped and finally n-doped). The fabrication process of the
photodetectors was performed by setting in the wires into SU8 and then
etching back using reactive ion etching to expose the tops of the wires. They
were then contacted on top using an optically opaque Ti/Au, while Al was
deposited on the back of the substrate, forming the back contact. At room
temperature the measured dark current density was below 2mA/cm2 at -0.1 V.
Interestingly, the measured dark current for the fabricated photodetector is
significantly below the best results reported for large area InAs
photodiodes, which typically exhibit ~100mA/cm2. This is unexpected since
InAsSb has a smaller band gap than InAs and the wires have a very large
surface area, both factors which would typically increase the current density
compared with conventional devices. In addition to this reduction in leakage
current density, when also considering enhanced absorption effects in
nanowires, there is the potential for an improvement in the signal to noise
ratio of 250 times, over the best reported InAs photodetectors. These results
shows a promising route for reducing the dark current in photodetector, and
highlight the potential of NWs as the next generation technology with a
potential for high performance and low cost optoelectronic devices.