Manohar Chirumamilla

Manohar Chirumamilla

Introduction

Education

Jan 2010 - Dec 2012
Istituto Italiano di Tecnologia
Ph. D
NANOSTRUCTURES

Experience

Dec 2017
Aalborg University
Jan 2014 - Apr 2014
Istituto Italiano di Tecnologia
Researcher
Nanochemistry
May 2017
Technical University of Hamburg
Postdoc
Optics and Electronic Materials
Apr 2014
Aalborg Universitet
Postdoctoral Researcher
Physics and Nanotechnology Department

Publications

9Publications

1126Reads

2Profile Views

336PubMed Central Citations

Metamaterial emitter for thermophotovoltaics stable up to 1400 °C.

Sci Rep 2019 May 10;9(1):7241. Epub 2019 May 10.

Institute of Optical and Electronic Materials, Hamburg University of Technology, Eissendorfer Strasse 38, Hamburg, 21073, Germany.

High temperature stable selective emitters can significantly increase efficiency and radiative power in thermophotovoltaic (TPV) systems. However, optical properties of structured emitters reported so far degrade at temperatures approaching 1200?°C due to various degradation mechanisms. We have realized a 1D structured emitter based on a sputtered W-HfO layered metamaterial and demonstrated desired band edge spectral properties at 1400?°C. To the best of our knowledge the temperature of 1400?°C is the highest reported for a structured emitter, so far. The spatial confinement and absence of edges stabilizes the W-HfO multilayer system to temperatures unprecedented for other nanoscaled W-structures. Only when this confinement is broken W starts to show the well-known self-diffusion behavior transforming to spherical shaped W-islands. We further show that the oxidation of W by atmospheric oxygen could be prevented by reducing the vacuum pressure below 10?mbar. When oxidation is mitigated we observe that the 20?nm spatially confined W films survive temperatures up to 1400?°C. The demonstrated thermal stability is limited by grain growth in HfO, which leads to a rupture of the W-layers, thus, to a degradation of the multilayer system at 1450?°C.

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http://dx.doi.org/10.1038/s41598-019-43640-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510906PMC
May 2019
787 Reads
3 Citations
5.078 Impact Factor

Multilayer tungsten-alumina-based broadband light absorbers for high-temperature applications

Opt. Mater. Exp. 2016 Aug 6;8 (2704)

Optical Materials Express

Efficient broadband absorption of visible and near-infrared light by low quality-factor metal-insulator-metal (MIM) resonators using refractory materials is reported. Omnidirectional absorption of incident light for broad angles of incidence and polarization insensitivity are observed for the fabricated MIM resonator. Excellent thermal stability of the absorber is demonstrated at high operating temperatures (800 °C). The experimental broadband absorption spectra show good agreement with simulations. The resonator with 12 nm top tungsten and 100 nm alumina spacer film shows absorbance above 95% in the range of 650 to 1750 nm. The absorption window is tunable in terms of the center wavelength, bandwidth, and the value of maximum absorbance (~98%) by simple variation of appropriate layer thicknesses. Owing to their flexibility, ease of fabrication and low cost, the presented absorbers have the potential for a wide range of applications, including the use in commonly used infrared bands or absorbers for (solar) thermo-photovoltaic energy conversion, where high absorbance and simultaneously low (thermal) re-radiation is of paramount importance.

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August 2016

60 Citations

Impact Factor 2.673

9 Reads

Near-infrared tailored thermal emission from wafer-scale continuous-film resonators.

Opt Express 2015 Sep;23(19):A1111-9

We experimentally investigate the near-infrared emission from simple-to-fabricate, continuous-film Fabry-Perot-type resonators, consisting only of unstructured dielectric and metallic films. We show that the proposed configuration is suitable for realization of narrowband emitters, tunable in ranges from mid- to near-infrared, and demonstrate emission centered at the wavelength of 1.7 ?m, which corresponds to the band gap energy of GaSb-based photodetectors. The emission is measured at 748 K and follows well the emissivity as predicted from reflection measurements and Kirchhoff's reciprocity. The considered emitter configuration is spectrally highly tunable and, consisting of only few unstructured layers, is amenable to wafer-scale fabrication at low cost by use of standard deposition procedures.

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http://dx.doi.org/10.1364/OE.23.0A1111DOI Listing
September 2015
23 Reads
3.488 Impact Factor

Bimetallic 3D nanostar dimers in ring cavities: recyclable and robust surface-enhanced Raman scattering substrates for signal detection from few molecules.

ACS Nano 2014 Aug 8;8(8):7986-94. Epub 2014 Aug 8.

Istituto Italiano di Tecnologia , Via Morego 30, 16163 Genova, Italy.

Top-down fabrication of electron-beam lithography (EBL)-defined metallic nanostructures is a successful route to obtain extremely high electromagnetic field enhancement via plasmonic effects in well-defined regions. To this aim, various geometries have been introduced such as disks, triangles, dimers, rings, self-similar lenses, and more. In particular, metallic dimers are highly efficient for surface-enhanced Raman spectroscopy (SERS), and their decoupling from the substrate in a three-dimensional design has proven to further improve their performance. However, the large fabrication time and cost has hindered EBL-defined structures from playing a role in practical applications. Here we present three-dimensional nanostar dimer devices that can be recycled via maskless metal etching and deposition processes, due to conservation of the nanostructure pattern in the 3D geometry of the underlying Si substrate. Furthermore, our 3D-nanostar-dimer-in-ring structures (3D-NSDiRs) incorporate several advantageous aspects for SERS by enhancing the performance of plasmonic dimers via an external ring cavity, by efficient decoupling from the substrate through an elevated 3D design, and by bimetallic AuAg layers that exploit the increased performance of Ag while maintaining the biocompatibility of Au. We demonstrate SERS detection on rhodamine and adenine at extremely low density up to the limit of few molecules and analyze the field enhancement of the 3D-NSDiRs with respect to the exciting wavelength and metal composition.

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http://dx.doi.org/10.1021/nn5020038DOI Listing
August 2014
19 Reads
67 Citations
13.709 Impact Factor

Plasmon resonance tuning in metal nanostars for surface enhanced Raman scattering.

Nanotechnology 2014 Jun 21;25(23):235303. Epub 2014 May 21.

Istituto Italiano di Tecnologia, Via Morego 30, 16131 Genova, Italy.

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http://dx.doi.org/10.1088/0957-4484/25/23/235303DOI Listing
June 2014
25 Reads
2 Citations
3.821 Impact Factor

3D nanostar dimers with a sub-10-nm gap for single-/few-molecule surface-enhanced raman scattering.

Adv Mater 2014 Apr 22;26(15):2353-8. Epub 2014 Jan 22.

Nanostructures, Istituto Italiano di Tecnologia, via Morego 30, Genova, 16163, Italy.

Plasmonic nanostar-dimers, decoupled from the substrate, have been fabricated by combining electron-beam lithography and reactive-ion etching techniques. The 3D architecture, the sharp tips of the nanostars and the sub-10 nm gap size promote the formation of giant electric-field in highly localized hot-spots. The single/few molecule detection capability of the 3D nanostar-dimers has been demonstrated by Surface-Enhanced Raman Scattering.

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http://dx.doi.org/10.1002/adma.201304553DOI Listing
April 2014
158 Reads
201 Citations
21.950 Impact Factor

Plasmon based biosensor for distinguishing different peptides mutation states.

Sci Rep 2013 ;3:1792

Nanostructures, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy.

Periodic and reproducible gold nanocuboids with various matrix dimensions and with different inter-particle gaps were fabricated by means of top-down technique. Rhodamine 6G was used as a probe molecule to optimize the design and the fabrication of the cuboid nanostructures. The electric field distribution for the nanocuboids with varying matrix dimensions/inter-particle gap was also investigated. These SERS devices were employed as biosensors through the investigation of both myoglobin and wild/mutated peptides. The results demonstrate the probing and the screening of wild/mutated BRCA1 peptides, thus opening a path for the fabrication of simple and cheap SERS device capable of early detection of several diseases.

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http://dx.doi.org/10.1038/srep01792DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3647166PMC
February 2014
39 Reads
5.078 Impact Factor

Interplay between electric and magnetic effect in adiabatic polaritonic systems.

Opt Express 2013 Mar;21(6):7538-48

Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163 Genova, Italy.

We report on the possibility of realizing adiabatic compression of polaritonic wave on a metallic conical nano-structure through an oscillating electric potential (quasi dynamic regime). By comparing this result with an electromagnetic wave excitation, we were able to relate the classical lighting-rod effect to adiabatic compression. Furthermore, we show that while the magnetic contribution plays a marginal role in the formation of adiabatic compression, it provides a blue shift in the spectral region. In particular, magnetic permeability can be used as a free parameter for tuning the polaritonic resonances. The peculiar form of adiabatic compression is instead dictated by both the source and the metal permittivity. The analysis is performed by starting from a simple electrostatic system to end with the complete electromagnetic one through intermediate situations such as the quasi-electrostatic and quasi-dynamic regimes. Each configuration is defined by a particular set of equations which allows to clearly determine the individual role played by the electric and magnetic contribution in the generation of adiabatic compression. We notice that these findings can be applied for the realization of a THz nano-metric generator.

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http://dx.doi.org/10.1364/OE.21.007538DOI Listing
March 2013
29 Reads
3.488 Impact Factor

Terahertz Dipole Nanoantenna Arrays: Resonance Characteristics.

Plasmonics 2013 Mar 24;8(1):133-138. Epub 2012 Aug 24.

Fondazione Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genoa, Italy.

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http://dx.doi.org/10.1007/s11468-012-9439-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3597338PMC
March 2013
46 Reads
3 Citations
2.240 Impact Factor