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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

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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.