Shashi Paul - Academia.edu (original) (raw)

Papers by Shashi Paul

Scientific Reports, 2016

The work described in this paper focuses on the utilisation of silicon nanowires as the informati... more The work described in this paper focuses on the utilisation of silicon nanowires as the information storage element in flash-type memory devices. Silicon nanostructures have attracted attention due to interesting electrical and optical properties, and their potential integration into electronic devices. A detailed investigation of the suitability of silicon nanowires as the charge storage medium in two-terminal non-volatile memory devices are presented in this report. The deposition of the silicon nanostructures was carried out at low temperatures (less than 400 °C) using a previously developed a novel method within our research group. Two-terminal non-volatile (2TNV) memory devices and metal-insulator-semiconductor (MIS) structures containing the silicon nanowires were fabricated and an in-depth study of their characteristics was carried out using current-voltage and capacitance techniques.

Nickel oxide has been investigated for several potential applications, namely, ultraviolet detect... more Nickel oxide has been investigated for several potential applications, namely, ultraviolet detectors, electro chromic devices, displays, diodes for light emitting, transparent conductive electrode, and optoelectronic devices. These applications require an in depth analysis of nickel oxide prior to its exploration in aforementioned devices. Optical properties of materials were investigated by depositing thin film of nickel oxide on different substrates in order to understand if the choice of substrate can have effect on deducing various optical parameters and can lead to wrong conclusions. In view of this, we have investigated optical properties of nickel oxide deposited on different substrates (glass, transparent plastic, sapphire, potassium bromide, and calcium fluoride).

Journal of Optoelectronics and Advanced Materials

In recent years, the interest in the application of organic materials in electronic devices (ligh... more In recent years, the interest in the application of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has shown a rapid increase. A new family of organic electronic device is organic memory device. These devices, based on a thin film of nano-sized particles and small molecules embledded in an organic layer attracted considerable attention. This work presents the polymer memory device which is made of a blend of poly(vinyl acetate) and ferroelectric barium titanate nanoparticles. A polymer blend of polyvinyl acetate and barium titanate (BaTiO 3) nanoparticles was prepared in methanol and spin coated onto a glass substrate marked with thin Al tracks and top contacts were evaporated onto the blend after drying -this resulted in a metal-organic-metal (MOM) structure. The current-voltage (I-V) behaviour of MOM devices shows that the devices can be switched from a high conductivity state to a low conductivity state, by applying an exte...

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences

Growth in the use of organic materials in the fabrication of electronic devices is on the rise. R... more Growth in the use of organic materials in the fabrication of electronic devices is on the rise. Recently, some attempts have been undertaken to manufacture polymer memory devices. Such devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductivity states ('high' and 'low') when a voltage is applied, thus rendering the structures suitable for data retention. In this paper, we describe an attempt to fabricate memory devices using ferroelectric nanoparticles embedded in an organic polymer. This paper also discusses issues related to the observed memory effect.

Thin Solid Films

For the last a few decades the interest in using organic materials in electronic applications (li... more For the last a few decades the interest in using organic materials in electronic applications (light emitting diodes, field effect transistors, solar cells, etc) has increased rapidly. Recently, organic materials have also been used to realise electronic memory devices. These devices show two electrical conductance states ("high" and "low") when voltage is applied. The memory effect in these devices with simple structure based on a thin film of nano-sized particles and/or small molecules embedded in an organic layer was demonstrated. This work investigates organic memory devices based on organic materials–blend between small organic molecules (TTF and TCNE) and polymer (PVAc).

ECS Transactions

Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organ... more Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states ("1" and "0") when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of non-volatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated. This study is aimed at further understanding the electrical bistability observed in such devices. This work also investigates if an electrical charge can be transferred to gold nano-particles and, between small molecule complexes.

Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organ... more Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states ("1" and "0") when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of nonvolatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated. This study is aimed at further understanding the electrical bistability observed in such devices. This work also investigates if an electrical charge can be transferred to gold nano-particles and, between small molecule complexes.

The 55 peer-reviewed papers collected here together offer a plenitude of up-to-date information o... more The 55 peer-reviewed papers collected here together offer a plenitude of up-to-date information on “Adaptive, Active and Multifunctional Smart Materials Systems”. The papers are conveniently arranged into: Chapter 1: Smart Inorganic Materials Systems, Chapter 2: Stimuli Responsive Polymers and Gels, Chapter 3: Luminescent and Chromogenic Materials Systems, Chapter 4: Multifunctional Composites and Porous Materials Systems, Chapter 5: Non-Volatile Memory Devices, Chapter 6: Multiferroics, Chapter 7: Metamaterials, Chapter 8: Graphene, Chapter 9: Multifunctional Materials for Energy Harvesting, Chapter 10: Actively Moving Polymers

Water research, Jan 14, 2015

As a high-quantum-efficiency photocatalyst, the serious photo-corrosion of silver phosphate (Ag3P... more As a high-quantum-efficiency photocatalyst, the serious photo-corrosion of silver phosphate (Ag3PO4), limits the practical applications in water purification and challenges us. Herein, Ag3PO4 is found to have a high stability under natural indoor weak light irradiation, suggesting that we can employ it by adopting a new application strategy. In our studies, rhodamine B (RhB, cationic dye), methyl orange (MO, anionic dye) and RhB-MO mixture aqueous solutions are used as the probing reaction for the degradation of organic wastewater. It is found that RhB, MO and RhB-MO can be completely degraded after 28 h under natural indoor weak light irradiation, indicating that multi-component organic contaminants can be efficiently degraded by Ag3PO4 under natural indoor weak light irradiation. The density of natural indoor weak light is measured to be 72cd, which is merely one-thousandth of 300 W xenon lamp (68.2 × 10(3)cd). Most importantly, Ag3PO4 shows a high stability under natural indoor w...

Applied Surface Science, 2015

ABSTRACT Abstract Nickel oxide has been investigated for several potential applications, namely, ... more ABSTRACT Abstract Nickel oxide has been investigated for several potential applications, namely, ultraviolet detectors, electro chromic devices, displays, diodes for light emitting, transparent conductive electrode, and optoelectronic devices. These applications require an in depth analysis of nickel oxide prior to its exploration in aforementioned devices. Optical properties of materials were investigated by depositing thin film of nickel oxide on different substrates in order to understand if the choice of substrate can have effect on deducing various optical parameters and can lead to wrong conclusions. In view of this, we have investigated optical properties of nickel oxide deposited on different substrates (glass, transparent plastic, sapphire, potassium bromide, and calcium fluoride).

Springer Proceedings in Mathematics & Statistics, 2015

We discuss a novel inverse problem in which the data is generated by the sequential contractive p... more We discuss a novel inverse problem in which the data is generated by the sequential contractive projections of the convolution of two unknown functions, both of which we aim to learn. The method is illustrated using an application that relates to the multiple inversions of image data recorded with a Scanning Electron Microscope, with the aim of learning the density of a given material sample and the microscopy correction function. Given the severe logistical difficulties in this application of taking multiple images at different viewing angles, a novel imaging experiment is undertaken, resulting in expansion of information. In lieu of training data, it is noted that the highly discontinuous material density function cannot be modelled using a Gaussian Process (GP) as the parametrisation of the required non-stationary covariance function of such a GP cannot be achieved without training data. Consequently, we resort to estimating values of the unknown functions at chosen locations in their domain-locations at which an image data are available. Image data across a range of resolutions leads to multiscale models which we use to estimate material densities from the micro-metre to nano-metre length scales. We discuss applications of the method in non-destructive learning of material density using simulated metallurgical image data, as well as perform inhomogeneity detection in multi-component composite on nano metre scales, by inverting real image data of a brick of nano-particles.

Nanoscience and Nanotechnology Letters, 2010

ABSTRACT In order to take advantage of the possibilities for constructing electronic devices, off... more ABSTRACT In order to take advantage of the possibilities for constructing electronic devices, offered by organic materials, it is essential to be able to control their electrical characteristics. By incorporating tetragonal barium titanate nanoparticles with a phosphonic acid ligand into a matrix of poly-vinyl acetate it has been shown that it is possible to increase the relative permittivity of the polymer. The upper limit of this effect has not yet been found, although carrying out the same work using barium titanate filler without the ligands exhibits behaviour consistent with conduction effects that occur at the percolation limit of the polymer. The devices produced using the ligand exhibit even distribution of nanoparticles within the polymer matrix and good and reproducible electrical characteristics.

EPJ Photovoltaics, 2014

We have demonstrated that by adding ferroelectric nanoparticles to poly(3-hexylthiophene) (P3HT) ... more We have demonstrated that by adding ferroelectric nanoparticles to poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) photovoltaic devices the relative efficiency can be increased compared to the same blend without these nanoparticles. In this work samples of 20 mg/ml concentrations of P3HT and PCBM were prepared in a 1:1 ratio and the samples prepared using ferroelectric barium titanate (BT) and strontium titanate (ST) nanoparticles in a 1:1:0.5 ratio. The samples were spin coated onto ITO coated glass with a layer of poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS). A top electrode of aluminium 1 cm 2 was deposited. The current-voltage characteristics of the devices were determined using a solar simulator and the absorption characteristics by UV-Vis spectroscopy. The samples with BT and ST exhibited increased absorption around 490 nm and increased open circuit voltage and short circuit current compared to the control P3HT/PCBM sample. The possible mechanism that helps to understand the increase in open circuit voltage and short circuit current is also proposed in this work.

Advances in Science and Technology, 2008

Page 1. Gold Nanoparticle Based Electrically Rewritable Polymer Memory Devices D. Prime 1, a , S.... more Page 1. Gold Nanoparticle Based Electrically Rewritable Polymer Memory Devices D. Prime 1, a , S. Paul 1,b 1 Emerging Technologies Research Centre, De Montfort University, The Gateway, Leicester LE1 9BH, UK. adprime@dmu.ac.uk, bpshashi@dmu.ac.uk ...

Materials Research Society Symposium Proceedings, 2008

In this work, we propose a hybrid inorganic/organic memory device that is fabricated using simple... more In this work, we propose a hybrid inorganic/organic memory device that is fabricated using simple techniques at a temperature compatible with large area plastic substrate materials. The devices are a combination of the organic polymers polystyrene and polyvinyl acetate and nanorods of zinc oxide (ZnO), grown via a hydrothermal process which uses nanoparticles of ZnO as growth precursors.

Materials Research Society Symposium Proceedings, 2008

In recent years, interest in applications of organic materials in electronic devices (light emitt... more In recent years, interest in applications of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has increased rapidly. The advantages of organic materials are the ease of processing, lower production costs and structural flexibility allowing achievement of the desired electrical and mechanical characteristics. Very recently, there have been demonstrations of blends of polymer and metal nanoparticles and/or small organic molecules in memory devices; such memory devices are called polymer memory devices (PMDs). These devices show two electrical conductance states ("high" and "low") when voltage is applied, thus rendering the structures suitable for data retention.

MRS Proceedings, 2009

ABSTRACT The influence of native point defects on the electrical and optical stability of zinc ox... more ABSTRACT The influence of native point defects on the electrical and optical stability of zinc oxide (ZnO) layers in air produced by reactive RF magnetron sputtering is investigated. ZnO thin films are strongly affected by oxygen (O2) molecules in ambient atmosphere. For instance, surface defects such as oxygen vacancies act as adsorption sites of O2 molecules, and the chemisorption of O2 molecules depletes the surface electronic states and reduces channel conductivity. Thin films of ZnO produced have electrical resistivities between 8.6 × 103 and 8.3 × 108 Ω-cm, and were found to be electrically-stable in air. TFTs fabricated using these films exhibited effective mobilities of ∼3 cm2V-1s-1 and the threshold voltage shifts by < 5 V under gate bias stress of 1 MV/cm for up to 104 s.

2014 IEEE Workshop on Statistical Signal Processing (SSP), 2014

ABSTRACT A major limiting factor in the performance of MIMO-CDMA systems is multiple access inter... more ABSTRACT A major limiting factor in the performance of MIMO-CDMA systems is multiple access interference (MAI) which can reduce the system capacity as well as bit error rate (BER). Thus, statistical characterization of MAI is vital in analyzing the performance of such systems. Since, the statistical analysis of MAI in MIMO-CDMA is quite involved especially in the presence of fading channels, existing works in literature employ suboptimal approaches to detect the subscriber without involving the need for MAI statistics such as successive interference cancellation (SIC) and parallel interference cancellation (PIC). To date, the exact characterization of multiple access interference in MIMO-CDMA is an unsolved problem. In this paper, we derive the expressions for the probability density function of MAI and MAI plus noise in MIMO-CDMA systems in the presence of both Rayleigh fading channels and additive Gaussian noise. Simulation results show that the theoretical predictions are very well substantiated.

Scientific Reports, 2016

The work described in this paper focuses on the utilisation of silicon nanowires as the informati... more The work described in this paper focuses on the utilisation of silicon nanowires as the information storage element in flash-type memory devices. Silicon nanostructures have attracted attention due to interesting electrical and optical properties, and their potential integration into electronic devices. A detailed investigation of the suitability of silicon nanowires as the charge storage medium in two-terminal non-volatile memory devices are presented in this report. The deposition of the silicon nanostructures was carried out at low temperatures (less than 400 °C) using a previously developed a novel method within our research group. Two-terminal non-volatile (2TNV) memory devices and metal-insulator-semiconductor (MIS) structures containing the silicon nanowires were fabricated and an in-depth study of their characteristics was carried out using current-voltage and capacitance techniques.

Nickel oxide has been investigated for several potential applications, namely, ultraviolet detect... more Nickel oxide has been investigated for several potential applications, namely, ultraviolet detectors, electro chromic devices, displays, diodes for light emitting, transparent conductive electrode, and optoelectronic devices. These applications require an in depth analysis of nickel oxide prior to its exploration in aforementioned devices. Optical properties of materials were investigated by depositing thin film of nickel oxide on different substrates in order to understand if the choice of substrate can have effect on deducing various optical parameters and can lead to wrong conclusions. In view of this, we have investigated optical properties of nickel oxide deposited on different substrates (glass, transparent plastic, sapphire, potassium bromide, and calcium fluoride).

Journal of Optoelectronics and Advanced Materials

In recent years, the interest in the application of organic materials in electronic devices (ligh... more In recent years, the interest in the application of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has shown a rapid increase. A new family of organic electronic device is organic memory device. These devices, based on a thin film of nano-sized particles and small molecules embledded in an organic layer attracted considerable attention. This work presents the polymer memory device which is made of a blend of poly(vinyl acetate) and ferroelectric barium titanate nanoparticles. A polymer blend of polyvinyl acetate and barium titanate (BaTiO 3) nanoparticles was prepared in methanol and spin coated onto a glass substrate marked with thin Al tracks and top contacts were evaporated onto the blend after drying -this resulted in a metal-organic-metal (MOM) structure. The current-voltage (I-V) behaviour of MOM devices shows that the devices can be switched from a high conductivity state to a low conductivity state, by applying an exte...

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences

Growth in the use of organic materials in the fabrication of electronic devices is on the rise. R... more Growth in the use of organic materials in the fabrication of electronic devices is on the rise. Recently, some attempts have been undertaken to manufacture polymer memory devices. Such devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductivity states ('high' and 'low') when a voltage is applied, thus rendering the structures suitable for data retention. In this paper, we describe an attempt to fabricate memory devices using ferroelectric nanoparticles embedded in an organic polymer. This paper also discusses issues related to the observed memory effect.

Thin Solid Films

For the last a few decades the interest in using organic materials in electronic applications (li... more For the last a few decades the interest in using organic materials in electronic applications (light emitting diodes, field effect transistors, solar cells, etc) has increased rapidly. Recently, organic materials have also been used to realise electronic memory devices. These devices show two electrical conductance states ("high" and "low") when voltage is applied. The memory effect in these devices with simple structure based on a thin film of nano-sized particles and/or small molecules embedded in an organic layer was demonstrated. This work investigates organic memory devices based on organic materials–blend between small organic molecules (TTF and TCNE) and polymer (PVAc).

ECS Transactions

Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organ... more Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states ("1" and "0") when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of non-volatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated. This study is aimed at further understanding the electrical bistability observed in such devices. This work also investigates if an electrical charge can be transferred to gold nano-particles and, between small molecule complexes.

Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organ... more Nano-composite polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and nanoparticles) between two metal electrodes. These devices show two electrical conductance states ("1" and "0") when voltage is applied, thus rendering the structures suitable for data retention. These two states can be viewed as the realisation of nonvolatile memory. Nano-composite polymer memory devices comprising of a blend of a polymer and small molecules and/or nanoparticles are investigated. This study is aimed at further understanding the electrical bistability observed in such devices. This work also investigates if an electrical charge can be transferred to gold nano-particles and, between small molecule complexes.

The 55 peer-reviewed papers collected here together offer a plenitude of up-to-date information o... more The 55 peer-reviewed papers collected here together offer a plenitude of up-to-date information on “Adaptive, Active and Multifunctional Smart Materials Systems”. The papers are conveniently arranged into: Chapter 1: Smart Inorganic Materials Systems, Chapter 2: Stimuli Responsive Polymers and Gels, Chapter 3: Luminescent and Chromogenic Materials Systems, Chapter 4: Multifunctional Composites and Porous Materials Systems, Chapter 5: Non-Volatile Memory Devices, Chapter 6: Multiferroics, Chapter 7: Metamaterials, Chapter 8: Graphene, Chapter 9: Multifunctional Materials for Energy Harvesting, Chapter 10: Actively Moving Polymers

Water research, Jan 14, 2015

As a high-quantum-efficiency photocatalyst, the serious photo-corrosion of silver phosphate (Ag3P... more As a high-quantum-efficiency photocatalyst, the serious photo-corrosion of silver phosphate (Ag3PO4), limits the practical applications in water purification and challenges us. Herein, Ag3PO4 is found to have a high stability under natural indoor weak light irradiation, suggesting that we can employ it by adopting a new application strategy. In our studies, rhodamine B (RhB, cationic dye), methyl orange (MO, anionic dye) and RhB-MO mixture aqueous solutions are used as the probing reaction for the degradation of organic wastewater. It is found that RhB, MO and RhB-MO can be completely degraded after 28 h under natural indoor weak light irradiation, indicating that multi-component organic contaminants can be efficiently degraded by Ag3PO4 under natural indoor weak light irradiation. The density of natural indoor weak light is measured to be 72cd, which is merely one-thousandth of 300 W xenon lamp (68.2 × 10(3)cd). Most importantly, Ag3PO4 shows a high stability under natural indoor w...

Applied Surface Science, 2015

ABSTRACT Abstract Nickel oxide has been investigated for several potential applications, namely, ... more ABSTRACT Abstract Nickel oxide has been investigated for several potential applications, namely, ultraviolet detectors, electro chromic devices, displays, diodes for light emitting, transparent conductive electrode, and optoelectronic devices. These applications require an in depth analysis of nickel oxide prior to its exploration in aforementioned devices. Optical properties of materials were investigated by depositing thin film of nickel oxide on different substrates in order to understand if the choice of substrate can have effect on deducing various optical parameters and can lead to wrong conclusions. In view of this, we have investigated optical properties of nickel oxide deposited on different substrates (glass, transparent plastic, sapphire, potassium bromide, and calcium fluoride).

Springer Proceedings in Mathematics & Statistics, 2015

We discuss a novel inverse problem in which the data is generated by the sequential contractive p... more We discuss a novel inverse problem in which the data is generated by the sequential contractive projections of the convolution of two unknown functions, both of which we aim to learn. The method is illustrated using an application that relates to the multiple inversions of image data recorded with a Scanning Electron Microscope, with the aim of learning the density of a given material sample and the microscopy correction function. Given the severe logistical difficulties in this application of taking multiple images at different viewing angles, a novel imaging experiment is undertaken, resulting in expansion of information. In lieu of training data, it is noted that the highly discontinuous material density function cannot be modelled using a Gaussian Process (GP) as the parametrisation of the required non-stationary covariance function of such a GP cannot be achieved without training data. Consequently, we resort to estimating values of the unknown functions at chosen locations in their domain-locations at which an image data are available. Image data across a range of resolutions leads to multiscale models which we use to estimate material densities from the micro-metre to nano-metre length scales. We discuss applications of the method in non-destructive learning of material density using simulated metallurgical image data, as well as perform inhomogeneity detection in multi-component composite on nano metre scales, by inverting real image data of a brick of nano-particles.

Nanoscience and Nanotechnology Letters, 2010

ABSTRACT In order to take advantage of the possibilities for constructing electronic devices, off... more ABSTRACT In order to take advantage of the possibilities for constructing electronic devices, offered by organic materials, it is essential to be able to control their electrical characteristics. By incorporating tetragonal barium titanate nanoparticles with a phosphonic acid ligand into a matrix of poly-vinyl acetate it has been shown that it is possible to increase the relative permittivity of the polymer. The upper limit of this effect has not yet been found, although carrying out the same work using barium titanate filler without the ligands exhibits behaviour consistent with conduction effects that occur at the percolation limit of the polymer. The devices produced using the ligand exhibit even distribution of nanoparticles within the polymer matrix and good and reproducible electrical characteristics.

EPJ Photovoltaics, 2014

We have demonstrated that by adding ferroelectric nanoparticles to poly(3-hexylthiophene) (P3HT) ... more We have demonstrated that by adding ferroelectric nanoparticles to poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) photovoltaic devices the relative efficiency can be increased compared to the same blend without these nanoparticles. In this work samples of 20 mg/ml concentrations of P3HT and PCBM were prepared in a 1:1 ratio and the samples prepared using ferroelectric barium titanate (BT) and strontium titanate (ST) nanoparticles in a 1:1:0.5 ratio. The samples were spin coated onto ITO coated glass with a layer of poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS). A top electrode of aluminium 1 cm 2 was deposited. The current-voltage characteristics of the devices were determined using a solar simulator and the absorption characteristics by UV-Vis spectroscopy. The samples with BT and ST exhibited increased absorption around 490 nm and increased open circuit voltage and short circuit current compared to the control P3HT/PCBM sample. The possible mechanism that helps to understand the increase in open circuit voltage and short circuit current is also proposed in this work.

Advances in Science and Technology, 2008

Page 1. Gold Nanoparticle Based Electrically Rewritable Polymer Memory Devices D. Prime 1, a , S.... more Page 1. Gold Nanoparticle Based Electrically Rewritable Polymer Memory Devices D. Prime 1, a , S. Paul 1,b 1 Emerging Technologies Research Centre, De Montfort University, The Gateway, Leicester LE1 9BH, UK. adprime@dmu.ac.uk, bpshashi@dmu.ac.uk ...

Materials Research Society Symposium Proceedings, 2008

In this work, we propose a hybrid inorganic/organic memory device that is fabricated using simple... more In this work, we propose a hybrid inorganic/organic memory device that is fabricated using simple techniques at a temperature compatible with large area plastic substrate materials. The devices are a combination of the organic polymers polystyrene and polyvinyl acetate and nanorods of zinc oxide (ZnO), grown via a hydrothermal process which uses nanoparticles of ZnO as growth precursors.

Materials Research Society Symposium Proceedings, 2008

In recent years, interest in applications of organic materials in electronic devices (light emitt... more In recent years, interest in applications of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has increased rapidly. The advantages of organic materials are the ease of processing, lower production costs and structural flexibility allowing achievement of the desired electrical and mechanical characteristics. Very recently, there have been demonstrations of blends of polymer and metal nanoparticles and/or small organic molecules in memory devices; such memory devices are called polymer memory devices (PMDs). These devices show two electrical conductance states ("high" and "low") when voltage is applied, thus rendering the structures suitable for data retention.

MRS Proceedings, 2009

ABSTRACT The influence of native point defects on the electrical and optical stability of zinc ox... more ABSTRACT The influence of native point defects on the electrical and optical stability of zinc oxide (ZnO) layers in air produced by reactive RF magnetron sputtering is investigated. ZnO thin films are strongly affected by oxygen (O2) molecules in ambient atmosphere. For instance, surface defects such as oxygen vacancies act as adsorption sites of O2 molecules, and the chemisorption of O2 molecules depletes the surface electronic states and reduces channel conductivity. Thin films of ZnO produced have electrical resistivities between 8.6 × 103 and 8.3 × 108 Ω-cm, and were found to be electrically-stable in air. TFTs fabricated using these films exhibited effective mobilities of ∼3 cm2V-1s-1 and the threshold voltage shifts by < 5 V under gate bias stress of 1 MV/cm for up to 104 s.

2014 IEEE Workshop on Statistical Signal Processing (SSP), 2014

ABSTRACT A major limiting factor in the performance of MIMO-CDMA systems is multiple access inter... more ABSTRACT A major limiting factor in the performance of MIMO-CDMA systems is multiple access interference (MAI) which can reduce the system capacity as well as bit error rate (BER). Thus, statistical characterization of MAI is vital in analyzing the performance of such systems. Since, the statistical analysis of MAI in MIMO-CDMA is quite involved especially in the presence of fading channels, existing works in literature employ suboptimal approaches to detect the subscriber without involving the need for MAI statistics such as successive interference cancellation (SIC) and parallel interference cancellation (PIC). To date, the exact characterization of multiple access interference in MIMO-CDMA is an unsolved problem. In this paper, we derive the expressions for the probability density function of MAI and MAI plus noise in MIMO-CDMA systems in the presence of both Rayleigh fading channels and additive Gaussian noise. Simulation results show that the theoretical predictions are very well substantiated.