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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: 黑料网, 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: Introduction to advances in emerging thermoelectric materials and devices dc.contributor.author: Manjunatha, Krishna Nama; Paul, Shashi; Sahu, Satyajit; Zebarjadi, Mona dc.description.abstract: Due to the growing global energy demand and the increasing adoption of sustainable and clean energy solutions, research in thermoelectric generators (TEGs) has intensified, leading to the development of novel materials that are earth-abundant, non-toxic, and produced at low cost. The direct conversion of heat into electricity is enabled by thermoelectric materials, which have gained significant attention because of their potential for clean energy harvesting. TEGs have recently gained popularity mainly due to their simple device structure and operation, being lightweight, noise-free and solid-state (there is no ongoing maintenance as there are no moving parts), and the possibility to integrate them with various devices that produce heat as a by-product. The performance of TEGs is determined by the dimensionless thermoelectric figure of merit (ZT). dc.description: open access article

  • dc.title: Advances in Gallium Oxide: Properties, Applications, and Future Prospects dc.contributor.author: Ganguly, Swapnodoot; Nama Manjunatha, Krishna; Paul, Shashi dc.description.abstract: The traditional domination of silicon (Si) in device fabrication is increasingly infiltrated by state鈥恛f鈥恡he鈥恆rt wide bandgap semiconductors such as gallium nitride (GaN) and silicon carbide (SiC). However, the performance of these wide bandgap semiconductors has not yet exceeded the optical material limitation, which leaves ample room for further development. Gallium oxide (Ga2O3) has surfaced as the preferred material for next鈥恎eneration device fabrication, as it has a wider bandgap (鈮�4.5鈥�5.7聽eV), an estimated twofold greater breakdown field strength of 8 MV cm鈭�1, and a higher Baliga's figure of merit(BFOM) (>3000) than SiC and GaN, therefore pushing the limit. In this review, the properties of gallium oxide, several methods for epitaxial growth, its energy band, and its broad spectrum of applications are discussed. Metals for achieving different types of contact and the influence of interfacial reactions are additionally assessed. Furthermore, defects and challenges such as p鈥恡ype doping, integration with heterostructures, the formation of superlattices, and thermal management associated with the use of this material are also reviewed. dc.description: open access article

  • dc.title: Inkjet-printed graphene oxide memory cells on paper for flexible electronics dc.contributor.author: Salaoru, Iulia; Worsley, Myles; Fern, George; Paul, Shashi dc.description.abstract: A number of two-dimensional (2D) materials have been explored for various applications, from electronic transistors to energy generation and storage. In this work, we explored the possibility of using reduced graphene oxide (rGO) in emerging two terminal memory devices using a printing technique. The fabricated memory devices were analysed using scanning electron microscopy, Raman spectroscopy, optical microscopy, and in-depth electrical measurements. We experimentally demonstrated that rGO memory devices fabricated via inkjet printing exhibit bipolar switching without the required electroforming step, with an on/off ratio of 3 orders of magnitude. The inkjet-printed approach allows for the layering of memory devices on each other, leading to an increase in information storage density. dc.description: open access article

  • 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: Investigation on the Mist intensity to deposit Gallium Oxide thin films by Mist Chemical Vapour Deposition (M鈥怌VD) dc.contributor.author: Ganguly, Swapnodoot; Manjunatha, Krishna Nama; Paul, Shashi dc.description.abstract: This study demonstrates a novel, simple and robust Mist鈥怌VD (M鈥怌VD) compatible with existing industrial practices to deposit gallium oxide thin films and influence of mist intensity on the properties of gallium oxide. The intensity of the mist generation has been optimized to obtain smooth and uniform thin films. The thin film deposited in this work is mixed phase polycrystalline gallium oxide. UV鈥怴is NIR spectroscopy and photo response of thin film unveils that gallium oxide thin film is responsive to ultra鈥恦iolet wavelengths including deep UVC and UVB bands and the mist generation intensity has negligible influence on the bandgap of the thin film. Thickness of thin film can be altered by varying the mist intensity. It has been observed that there is no appreciable impact on refractive index of varying mist intensity. Morphological studies prove the formation of ultra鈥恠mooth thin film with rms value of 0.628nm; which is closer and/or better than conventional semiconductor thin film deposition processes used for depositing Ga dc.description: open access article

  • dc.title: Electrical Bistability by Creating an Internal Electrical Field and Its Application in Emerging Two-terminal Electronic Memory Devices dc.contributor.author: Paul, Febin; Paul, Shashi dc.description.abstract: This chapter focusses on the electrical bistability observed in nanocomposite memory devices that have been studied over two decades. Bistability, in the context of memory devices, has been discussed and visual tools have been employed for its examination as a general mathematical function. The bistability observed in memory devices, in terms of electrical hysteresis, has been focussed and typical curves observed in several studies over the last fifty years have been consolidated and systematically examined. The development of the field has led to much confusion in terms of understanding of the device switching mechanism, which has been investigated in detail. The discrepancies in the proposed device behaviour and the observations have over time led to the rise of many opinions/models to explain the physics of the device conduction switching. In this chapter, the charge-trap models have been examined and solutions to some open questions have been proposed in terms of analysing at the system from the perspective of field generation, instead of the material interaction.

  • 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: Storing Electronic information on Semi-Metal Nanoparticles dc.contributor.author: Paul, Febin; Nama Manjunatha, Krishna; Paul, Shashi dc.description.abstract: This paper presents the use of selenium nanoparticles for the application of information storage in two terminal electronic memory devices. Selenium is a semi-metal with interesting electronic and optical properties that have seldom been studied in terms of electronic memory. In this study selenium nanoparticles have been demonstrated as an embedded charge storage layer between silicon oxide tunnel layer and silicon nitride blocking layer. The electrical characterisation demonstrates clear evidence that charge storage is taking place, and that it is indispensable without the presence of nanoparticles. AFM images show that selenium nanoparticles are almost uniformly distributed on Silicon substrate having a thin silicon dioxide tunnelling layer, and the electrical retention measurement shows potential for long term data storage 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. ; Open Access Article

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

Courses 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.

黑料网 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 黑料网:

黑料网 Shows the Benefits of Gold Nanoparticles for Organic Electronics:

黑料网 Shows the Benefits of Gold Nanoparticles for Organic Electronics:

Flexible memory has wide ranging application

ORCID number

0000-0002-7077-8235

shashipaul