AV大平台

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Professor Shashi Paul

Job: Professor of Nanoscience and Nanotechnology and working for Emerging Technologies Research Centre

Faculty: Computing, Engineering and Media

School/department: School of Engineering and Sustainable Development

Research group(s): Emerging Technologies Research Centre (EMTERC)

Address: AV大平台, The Gateway, Leicester, LE1 9BH, United Kingdom

T: +44 (0)116 207 8548

E: spaul@dmu.ac.uk

W: /emterc

 

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Personal profile

I graduated from Indian Institute of Science, Bangalore, India and have previously worked in Cambridge University., Durham University, and Rutgers University. My research interests include manufacturing and analysis of nano-materials and their applications into energy (e.g. photovoltaic solar cells), electronics (emerging electronic memory devices including neuromorphic) and biological sensors. My particular focus is on the development of materials manufacturing processes to reduce the carbon footprint and next generation electronic devices.

Research group affiliations

Institute of Engineering Sciences (IES)

Publications and outputs


  • dc.title: Schottky barrier formation on r.f.-plasma enhanced chemical vapour deposited hydrogenated amorphous carbon dc.contributor.author: Paul, Shashi; Clough, F. J. dc.description.abstract: This paper reports the fabrication and electrical characterization of sub-micron metal contacts to thin films of hydrogenated amorphous carbon deposited by the r.f.-plasma enhanced chemical vapour deposition technique. The I鈥揤 characteristics of 鈥渓arge鈥� area (diameter 0.5 mm) top metal contacts to amorphous carbon are consistent with bulk limited conduction by the Poole鈥揊renkel mechanism. The I鈥揤 characteristics of sub-micron metal contacts, formed at different locations on the same amorphous carbon film, range from symmetrical to highly asymmetrical with forward-to-reverse rectification ratios up to three orders of magnitude. Asymmetrical I鈥揤 characteristics and a linear C鈭�2鈥揤 response confirm, for the first time, Schottky barrier formation at the metal/amorphous carbon interface. Spatial non-uniformity in the composition of the hydrogenated amorphous carbon surface is indicated, which mirrors bulk inhomogeneity.

  • dc.title: Non鈥怹ero and Open鈥怢oop Current鈥揤oltage Characteristics in Electronic Memory Devices dc.contributor.author: Paul, Febin; Nama Manjunatha, Krishna; Paul, Shashi dc.description.abstract: This work focuses on the non-zero-crossing and open-loop current鈥搗oltage (I鈥揤) characteristics of electronic memory devices that are studied and focused on primarily for non-volatile memory storage applications. Gold nanoparticles-based devices are fabricated to understand possible non-crossing zero and open-loop current鈥搗oltage behavior, where a non-zero current and open loop I鈥揤 characteristics are observed at zero voltage. While other studies have attributed this behavior as a 鈥渂attery effect鈥�, this study presents an alternate perspective for non-redox-based charge storage memory devices. The electrical measurements clearly demonstrate that the non-zero current and open-loop characteristics are due to the charge trapping of the gold nanoparticles. The charge accumulation within the nanoparticle is observed to create a non-zero potential within the device and thereby encouraging such behavior, even though the applied external voltage is zero. The longstanding mystery in deciphering if electrical measurements or the charge storage device contributes toward non-zero property is unfurled in this article. A possible charge storage model is proposed and further verified using liquid crystals-based two terminal devices. The presence of internal potential leads to an offset within the devices, a non-zero current and open-loop I鈥揤 even when the external applied voltage is zero. dc.description: open access article

  • dc.title: Materials and challenges of 3D printing of emerging memory devices dc.contributor.author: Salaoru, Iulia; Ganguly, Swapnodoot; Morris, Dave; Paul, Shashi dc.description.abstract: The continuous development of the semiconductor industry to meet the increasing demand of modern electronic devices which can enhance computing capabilities is attributed to the exploration of efficient, simple, high-speed operation and multistate information storage capacity of electronic devices called memory devices. Nowadays, one of the main challenges the industry faces is limitations in manufacturing as the current fabrication pathway is complex and relies on the use of rigid substrates that do not match with the needs of industry for flexible, bendable electronics. 3D printing has a huge potential to address this challenge and to completely replace the current fabrication pathways and protocols. In this paper, the materials and the 3D printing technologies that have been explored to fabricate an emerging flexible, bendable memory device will be presented. dc.description: open access article

  • dc.title: Organic and Macromolecular Memory 鈥� Nanocomposite Bistable Memory Devices dc.contributor.author: Paul, Shashi dc.description.abstract: The primary aim in the memory devices is to produce structures that exhibit two distinct states when a certain type of stimulus (e.g. electric field or magnetic field) is applied. These two states can be viewed as the realization of memory devices. It is to be noted that the class of memory devices that is discussed in this chapter is based on the admixture of small molecules, nanoparticles, and polymers; such devices are referred to as polymer electronic memory devices. This chapter captured the key developments that have happened in the field of organic memory devices for the last two decades. This chapters include discussions on the progress in this field and address challenges that scholars are currently faced with, such as questions about the mechanism(s) of bistability, the conundrum of the experimental data, and the contradictions prevalent among the different groups and future directions. The chapter also introduces reader some basic terms, concepts and terminology often used in this field.

  • dc.title: To Be or Not to Be 鈥� Review of Electrical Bistability Mechanisms in Polymer Memory Devices dc.contributor.author: Paul, Febin; Paul, Shashi dc.description.abstract: Organic memory devices are a rapidly evolving field with much improvement in device performance, fabrication, and application. But the reports have been disparate in terms of the material behavior and the switching mechanisms in the devices. And, despite the advantages, the lack of agreement in regards to the switching behavior of the memory devices is the biggest challenge that the field must overcome to mature as a commercial competitor. This lack of consensus has been the motivation of this work wherein various works are compiled together to understand influencing factors in the memory devices. Different works are compared together to discover some clues about the nature of the switching occurring in the devices, along with some missing links that would require further investigation. The charge storage mechanism is critically analyzed alongside the various resistive switching mechanisms such as filamentary conduction, redox-based switching, metal oxide switching, and other proposed mechanisms. The factors that affect the switching process are also analyzed including the effect of nanoparticles, the effect of the choice of polymer, or even the effect of electrodes on the switching behavior and the performance parameters of the memory device. dc.description: open access article

  • dc.title: Comparative Study of Silicon Nanowires Grown From Ga, In, Sn, and Bi for Energy Harvesting dc.contributor.author: Manjunathan, Krishna Nama; Salaoru, Iulia; Milne, W.I; Paul, Shashi dc.description.abstract: A high density of silicon nanowires for solar cell applications was fabricated on a single crystalline silicon wafer, using low eutectic temperature metal catalysts, namely, gallium, indium, tin, and bismuth. The use of silicon nanowires is exploited for light trapping with an aim to enhance the efficiency of solar cells. Additionally, we have optimized the deposition parameters so that there is merely deposition of amorphous silicon along with the growth of silicon nanowires. Thus, it may improve the stability of silicon-based solar cells. The different catalysts used are extensively discussed with experimental results indicating stable growth and highly efficient silicon nanowires for photovoltaic applications. To test the stability, we measured the open-circuit voltage for four hours and the change in voltage was 卤0.05 V. The fabrication of all-crystalline silicon solar cells was demonstrated using the conventional mature industrial manufacturing process that is presently used for the amorphous silicon solar cells. To summarize, this research compares various post-transition metals as a catalyst for the growth of nanowires discussing their properties, and such silicon nanowires can be utilized in several other applications not only limited to photovoltaic research. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

  • dc.title: e-Information on wires- A First Step towards 2-Terminal Silicon Nanowires for Electronic Memory Devices dc.contributor.author: Saranti, Konstantina; Paul, Shashi dc.description.abstract: Presently, there is a rapid growth of interest in the area of flexible electronics. Benefits such as light weight, durability and low-cost are among the most appealing aspects. However, the high temperatures throughout the fabrication processes are still the main hurdle. In this study, the deposition of silicon nanowires (SiNWs) at low temperature (300藲C) using Tin (Sn) catalyst is studied. Silicon nanostructures have been the centre of research for many years for a number of applications in different areas. Chemical Vapour Deposition (CVD) and other industrial deposition techniques, for the growth of crystalline silicon micro- and nano structures use high temperatures and therefore are not compatible with temperature sensitive substrates. This work utilises a low temperature deposition method for the growth of SiNWs and creates a leeway to use flexible plastic sheets as substrates. The silicon nanowires were deposited by exploiting the Vapour-Liquid-Solid (VLS) material growth mechanism using Plasma Enhanced Chemical Vapour Deposition (PECVD) technique. The suitability of these structures, as an information storage material, for future flash and two terminals non-volatile memory devices are investigated. Strong charge storage behaviour with a retention time up to 5 hours was observed showing great potential for the future memory candidate. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

  • dc.title: Carrier selective metal-oxides for self-doped silicon nanowire solar cells dc.contributor.author: Manjunathan, Krishna Nama; Paul, Shashi dc.description.abstract: Selection of a material that serves multiple purposes is always beneficial for any electronic device including solar cells. This study investigates nickel oxide (NiO) as a multipurpose material to overcome the potential issues observed in traditional solar cells. A proof-of concept device is fabricated to understand the efficient hole transport from NiO while blocking electrons as determined by I-V measurements showing suppression of dark current and enhancement in the power conversion from the solar cell. Enhanced surface defects in the silicon nanowires (SiNWs) leading to the poor carrier collection is possible to be improved by the selection of wide bandgap metal-oxides that show high band offset for one carrier (electron/hole) while negligible band offset for another carrier (hole/electron) is discussed. Furthermore, Fermi level de-pinning for NiO sandwiched between different metal electrodes and SiNWs, signifying that the selection of appropriate metal electrodes is another key factor in improving the efficiency of solar cells; which is experimentally studied in this work. As fabricated solar cells in this work do not use high temperature diffused P[sbnd]N junction to separate the charge carriers neither toxic gases for doping SiNWs. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

  • dc.title: Wire-bar coating of doped Nickle oxide thin films from metal organic compounds dc.contributor.author: Nama Manjunatha, Krishna; Paul, Shashi dc.description.abstract: This study discusses the significance of aliovalent cations, especially monovalent compared to trivalent, which provide controlled doping and increase in the conductivity of nickel oxide (NiO) thin films. This report is a first proof of concept involving simple and economical K-bar, wire-wound deposition of doped and undoped NiO films. As deposited films have similar optical and electrical properties compared to the most commonly used deposition techniques for the deposition of NiO thin films. Doping of NiO from three different metal salts that have a different valencies (Cu1+, Zn2+, and Ga3+) as dopants for NiO thin films is investigated. This will help us understand the effect of monovalent, bivalent and trivalent ions towards the doping in NiO. Change in the structural, optical and electrical properties of NiO are investigated and compared amongst different metals (dopants) with different valencies. Furthermore, these properties are investigated in-depth by varying the concentration of the dopants (between 0鈥痑t.% and 8鈥痑t.%) within the NiO film. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

  • dc.title: Silicon Rising dc.contributor.author: Paul, Shashi dc.description.abstract: Silicon, as an electronic material, has played an enormous role in promoting the modern technical evolution in almost all fields. And, needless to say, it will continue its leadership until a better material is found. We are currently going through an exploration period to search out alternative materials. A number of different materials are have been proposed as challengers, but silicon (Si) is still the front runner, as far as complementary metaloxide- semiconductor (CMOS) technologies is concerned. Silicon is widely used in electronic industries in a number of forms, such as the amorphous silicon used in thin-film transistors (TFTs) in liquid-crystal display units, poly-silicon can be found in flash memory structures and photovoltaic solar cells, and single crystals are predominately used in CMOS technologies. Among the various forms of silicon embodiments, silicon nano-structures 鈥� for example, silicon nanowires 鈥� are also currently being explored, and for the last a few decades, there has been intense interest in how toprepare nanometre scale silicon.

Key research outputs

Memory effect in thin films of insulating polymer and C60 nanocomposites, Paul, S., Chhowalla, M. and Kanwal, A., Nanotechnology (2006), 17(1), pp. 145-151.

Langmuir-Blodgett film deposition of metallic nanoparticles and their application to electronic memory structures, Paul, S et al, Nano letters (2003), 3, 191-195.

Realisation of Non-volatile Memory Devices using Small Organic Molecules and Polymer”, S. Paul, IEEE Transaction on Nanotechnology, 2007, 6 , 191-195.

Ferroelectric nanoparticles in polyvinyl acetate (PVAc) matrix-A method to enhance the dielectric constant of polymers. D Black, I Salaoru, S Paul, Nanoscience and Nanotechnology Letters (2010), Volume 2, Issue 1, March 2010, Pages 41-45.

Prime, D. and Paul, S. (2010) First contact-charging of gold nanoparticles by electrostatic force, Applied Physics Letters, 96 (4) 043120.

Research interests/expertise

  • Organic and inorganic materials for plastic electronics (including printing techniques for their deposition)
  • Emerging Electronic Memory Devices (including neuromorphic)
  • New Growth Processes/Methods for Nano-structures/materials
  • Photovoltaic Solar Cells (organic and inorganic)
  • Energy Storage (Electrical and Heat)

Areas of teaching

  • Electrical & Electronic Principles 1 (ENGD1103)
  • Emerging Materials and Processes (ENGD3114)
  • Energy Conversion & Storage Systems (ENGD3121)
  • Physics of Semiconductor Devices (ENGT5128)
  • Study Skills and Research Methods (ENGT5214)

Qualifications

MSc, PhD

AV大平台 taught

MSc(Electronics Engineering)- Programme Leader, B.Engg (Mechanical Engineering), BSc(Energy Engineering) and a common module to all engineering disciplines in the school of engineering and sustainable development

Membership of external committees

The 4th International Conference “Smart Materials, Structures and Systems”- a part of CIMTEC2012 conference organising programme committee

Dr S Paul is member of international programme committee for the forthcoming Conference on Renewable Energies and Power Quality (ICREPQ) by the European Association for the Development of Renewable Energies, Environment and Power Quality (EA4EPQ)", (), 28-30 March, 2012, Santiago de Compostela, Spain.

The 3rd International Conference “Smart Materials, Structures and Systems” held in Acireale Catania District), Sicily, Italy, on June 8 to 13, 2008. Organised a special session on “Recent Development in Electrical Writable Organic Memory Devices”.

The 4th International Conference “Smart Materials, Structures and Systems” will be held in Acireale Catania District), Sicily, Italy, on June 8 to 13, 2008. Dr S Paul is organising a special session on “Emerging Non-volatile Memory Devices”.

Visiting Professor in the Physics department of Alexandru Ioan Cuza University of Iasi, Romania. From 24/12/2011 to 24/12/2013.

Membership of professional associations and societies

Association Name, period start, period end, description

Member IEEE (January, 2012 to December 2012)

Member Materials Research Society

Forthcoming events

Organising a special symposium on Emerging Memory Devices in CIMTEC2012

Conference attendance

Attended a number of international conferences (e.g.: IEEE, MRS, CIMTEC)

Current research students

1. Febin Paul (1st supervisor)
2. Swapnodoot Ganguly (2nd supervisor)
3. Chris Yang (1st supervisor)
4. Abdulrahaman Ogunji (1st supervisor)
5. Pratik Deorao Shende (1st supervisor)
6. Shashikala Madaiah (1st supervisor)
7. Maher Nahhas(1st supervisor)

Externally funded research grants information

  • Awarded an ICURe (Innovation & Commercialisation of University Research - funded by UKRI) £27k (from 1/1/2021 to 31/1/2021) for ‘Storing Electrical Energy in Silicon-Tin’ to explore commercialisation of his research. The CURe Programme offers university research teams with commercially-promising ideas funding and support to ‘get out of the lab’ and validate their ideas in the marketplace.
  • Energy Catalyst-3 - Creating electricity by reducing cost, payback time and Carbon footprint - An exploitation of a novel method into manufacturing Crystalline Silicon Photovoltaic solar Cells. (£70k) with 3 industrial partners.
  • EPSRC High Value Manufacturing (HVM) Catapult fellowship to work on the project “Manufacturing Silicon Nano-structure at low temperature – route to increase charge capacity and lower the cost of Li-Ion batteries” (£36,070)- February-2016 to February-2018.
  • EPSRC funding (#EP/E047785/1) on “Nano-Scale Rewritable Non-Volatile Polymer Memory Arrays”, principal investigator (£207k) – July-2007- November-2009.
  • National Physical Lab funding “Electrical Charging Mechanism in C60”, principal investigator (£20k)- October-2005 – September-2010.
  • EPSRC CASE Studentship (£57k) – October-2005 – March 2009.
  • “”, principle investigator, European Integrated Activity of Excellence and Networking for Nano and Micro- Electronics Analysis (FP6), December-2010
  • Hosting visitor from Iraq (6k) – 2013
  • Consultancy (AFM analysis) – 1k -2008.
  • EPSRC-DTA studentship (~40k) – 2008 for 3 years.

Internally funded research project information

RIF project: A Cleaner, Greener, Low Carbon Fabrication Process for Photovoltaic (PV) Solar Cells (PI). Start date: 01/04/10; End date: 01/07/10.

AV大平台PhD Bursary on Plastic compatiable Electronic Memory Devices, October-2011 to September 2014.

Published patents

  • GB2482915 - A low temperature method for the production of polycrystalline silicon, aligned silicon columns and silicon nanowires (Date Lodged: 20 August 2010, Granted on 5/2/2013).
  • GB2484743 - Organic photoconductive material (Filing date: 23 October 2010, Publication Date 25 April 2012, Granted in October, 2014).
  • 2 patent applications submitted in 2020.

Professional esteem indicators

Guest editor of the issue of the Philosophical Transaction of the Royal Society A, on the theme of “Making Nano-Bits Remember: A Recent Development in Organic Electronic Memory Devices”. Volume 367, Issue 1905, 28 October 2009.

Reviewer for a number of journals in the field of electronic materials and devices.

Visiting Professor, Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Romania.

Case studies

Nano-bits Enabled Application in storing electronic information and creating electrical energy:

Ribbon award – MRS Fall Meeting 2004, Boston, USA

News in Science -2004: http://www.sciencenews.org/view/generic/id/5717/title/Buckyballs_store_1s_and_0s_in_new_memory_device

Gold nanoparticles for memory storage: 

Organic electronic memory chip to be demonstrated in the UK

Huge breakthrough in tiny technology by DMU:

AV大平台 Shows the Benefits of Gold Nanoparticles for Organic Electronics:

AV大平台 Shows the Benefits of Gold Nanoparticles for Organic Electronics:

Flexible memory has wide ranging application

ORCID number

0000-0002-7077-8235

shashipaul