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Volume 3, Issue 4 (Suppl)
Nano Res Appl
ISSN: 2471-9838
November 07-08, 2017 Singapore
International Meeting on
Advanced Nanomaterials and Nanotechnology
Nanomaterials Meetings 2017
November 07-08, 2017
Page 22
Ultrahigh responsivity near infrared photo detectors based on single
semiconductor nanowires
I
n this report, we show that ultra-high responsivity (R>105-106A/Watts) Near Infra-Red
(NIR) photodetectors can be made from single strand of nanowires of semiconductors
like Si, Ge or molecular materials like Cu:TCNQ. The nanowires used were all grown
by vapor phase methods and the single nanowire devices were fabricated on SiO2/Si
substrate where the electrical leads were made using a combination of optical lithography
and nanolithography tools such as electron beam lithography and lift off or focused ion
beam or focused electron beam deposition methods. The typical device lengths are in
the range of 1-5 microns and then nanowire strands have a diameter <100 nm. The
distance between the electrodes was brought down to below 300 nm. In case of the
molecular material Cu: TCNQ, which gives a narrowband detector, a peak responsivity
of 10
4
-10
5
A/W can be reached at 405nm with nanowire of diameter 30nm. In case of Si
nanowires (diameter ~80-100nm), the response is broad band and a responsivity >10
4
A/W can be reached over the wavelength of 500nm to 1150 nm. For Ge nanowires, the
response can be seen even over broader wavelength region extending well into the NIR
region limited by the band-width of Ge (1850 nm). The peak responsivity in this case
can reach even 10
6
A/W at wavelength range 800 nm-1000 nm. Though not very large
reasonable responsivity, can also be seen from single strands of Y-junction CNT. The
ultra-high sensitivity in single nanowire devices are contributed by a number of factors
that include: (1) very close distance between electrodes, (2) small diameter allowing for
photo-transistor effects at the surface of nanowires and (3) diffusion of photo generated
carriers lowering the Schottky barrier at the contact interface.
Recent Publications
1. KDas, SMukherjee, SManna, S KRay and AKRaychaudhuri (2014) Single Si nanowire
(diameter ≤100 nm) based polarization sensitive near-infrared photodetector with
ultra-high responsivity. RSC Nanoscale; 6: 1123.
2. Sudeshna Samanta, Deepika Saini, Achintya Singha, Kaustuv Das, P R Bandaru, A
M Rao, and A K Raychaudhuri (2016) Photoresponse of a Single Y-Junction Carbon
Nanotube. ACS Applied Materials and Interfaces; 8: 19024.
Biography
A K Raychaudhuri has obtained his MSc from IIT Kanpur and PhD from Cornell University, Ithaca, USA. He had
Post-doctoral experience at the Max Planck Institute, Stuttgart as an Alexander von Humboldt Fellow. He has
worked as a Professor at Indian Institute Science Bangalore, the Director of National Physical Laboratory, New
Delhi and as the Director of S. N. Bose National Centre for Basic Sciences, Kolkata, where he is currently a
Distinguished Professor Emeritus and J C Bose Fellow. His research interests cover condensed matter physics
and materials physics. His current research mainly focuses on nanomaterials that include nanofabrications using
nanolithography techniques such as use of electron-beam and ion-beam lithography for fabrication of single
nanowires based devices including ultra-high responsivity single nanowire photodetectors. He is a Fellow of all the
Science Academies in India and is a winner of the S S Bhatnagar Award in Physical Sciences in 1994.
arup@bose.res.inA K Raychaudhuri
S. N. Bose National Centre for Basic
Sciences, India
A K Raychaudhuri, Nano Res Appl 2017, 3:4
DOI: 10.21767/2471-9838-C1-004
Proteomics Meeting 2017