Dr. Muhammad Naeem Awais - Academia.edu (original) (raw)
Papers by Dr. Muhammad Naeem Awais
The attributes of a memristor such as non-volatile, simple structure, no leakage current, and fas... more The attributes of a memristor such as non-volatile, simple structure, no leakage current, and fast switching speed have unfolded enormous opportunities for various analog and digital applications. It is imperative to develop an accurate physical model of the memristor in order to design digital applications. The hitherto published memristor modeling approaches do not match with the practical memristor dynamics. A new model is developed by considering Schottky contact at the metal-insulator-metal (MIM) interfaces. In this research work, a novel memristor is also fabricated to validate the proposed model. A bead polymer based on methyl methacrylate and n-butyl methacrylate (MMBM) is firstly used to explore the resistive switching properties of the device. A cost-effective screen printing technique is first demonstrated to deposit the resistive switching layer for the fabrication of the memristor. The resistive switching behavior is observed in the sandwiched layer with a silver (Ag) a...
2019 International Conference on Frontiers of Information Technology (FIT), 2019
People suffering from a neurological injury such as stroke or spinal cord injury can suffer from ... more People suffering from a neurological injury such as stroke or spinal cord injury can suffer from a partial or total loss of their limbs, including hands which can harm their quality of life. It can be countered by the use of prosthetic and robotic support. This article describes the development of a soft wearable robotic glove for stroke-affected patients with limited hand mobility. The developed prototype utilizes Electromyography (EMG) signals that control the system as per the user's intention through actuators. The prototype developed in this work is a cable driven system which eliminates the need of rigid frames and thereby allowing the weight of soft robotic glove to be less than 50 grams and provides flexibility and comfort to the user. The device aims to regulate the grip force of the patient and allows him/her to perform activities of daily life (like grasping a cup) without external help. To enhance the rehabilitation, the robotic glove can also be controlled by another sensor glove that can be worn by the user on their unaffected hand or by a physiotherapist. The glove worn on the affected hand mimics the movement of the sensor glove. The proposed system is cost effective and can be used to handle up to 500 grams of weight. The performance of the glove is evaluated for a stroke affected patients and aged persons to analyze the grip force provided by the device and the range of motion of grip. The results show that the offered assistive strength is sufficient to improve the stroke-affected hand.
Optimized use of computing resources is one of the basic requirements of constrained environments... more Optimized use of computing resources is one of the basic requirements of constrained environments like Internet of Things (IoT). Due to its constrained nature, small computing platforms are frequently used in different IoT solutions. Therefore, optimization of such small platforms can play an important role in an overall improved performance of such solutions. This paper demonstrates an optimized processor utilization by estimating and utilizing the gain time on a small platform. Gain time of a task is defined as the difference between Worst-Case Execution Time (WCET) and its Actual Execution Time (AET) at runtime. It is a practical parameter which is ignored in the theoretical design considerations. Consequently, the offline schedulability analysis of a scheduling algorithm is based only on the WCET which may result tin underutilization of the processing power. In this paper, we present an empirical analysis of the factors affecting the gain time of an application while considering...
Computers & Electrical Engineering, 2018
Reliability, performance and power consumption of a real-time multiprocessor system are negativel... more Reliability, performance and power consumption of a real-time multiprocessor system are negatively affected by high temperatures, spatial gradients and thermal cycles. Software-based load balancing techniques have been used for thermal management. The transfer of workload in such techniques is based on temperature estimation. In this paper, we proposed an online temperatureaware scheduling technique that performs load balancing based on dynamic temperature measurement at a fixed ambient temperature. Contrary to the static techniques that utilize the principle of temperature prediction, the proposed technique does not require any thermal history of workload and is effective for any kind of workload without prior knowledge. Moreover, it reduces the energy consumption and avoids the workload switching delays among the cores. The simulation results show that the technique reduces overall temperature up to 5%, thermal cycles up to 3% and lowers the temporal and spatial gradients compared to the commonly used techniques.
Journal of the Korean Physical Society, 2019
The prediction of the current-voltage (IV) characteristics of resistive switching devices has rem... more The prediction of the current-voltage (IV) characteristics of resistive switching devices has remained a challenge before their physical realization. This research work addresses the prediction of the IV characteristics and the bipolar switching mechanism of polymer-based resistive switches by examining their structures before their fabrication. The research was carried out through an analytical study of the device structure, thereby correlating the predicted IV curve to the in-situ IV characteristics of the device. Different types of the device structures were considered, depending upon the work function of the top and the bottom electrodes and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of the sandwiched layer. We concluded that the defects/traps within the sandwiched layer lead to the interface effect being the dominant switching mechanism driving the polymer-based resistive switches. Furthermore, we also found that the devices following the interface effect are driven from trap-limited space-charge-limited current (SCLC) conduction to trap-free SCLC conduction as their current conduction mechanisms.
International Journal of Distributed Sensor Networks, 2019
Thermal issues in microprocessors have become a major design constraint because of their adverse ... more Thermal issues in microprocessors have become a major design constraint because of their adverse effects on the reliability, performance and cost of the system. This article proposes an improvement in earliest deadline first, a uni-processor scheduling algorithm, without compromising its optimality in order to reduce the thermal peaks and variations. This is done by introducing a factor of fairness to earliest deadline first algorithm, which introduces idle intervals during execution and allows uniform distribution of workload over the time. The technique notably lowers the number of context switches when compare with the previous thermal-aware scheduling algorithm based on the same amount of fairness. Although, the algorithm is proposed for uni-processor environment, it is also applicable to partitioned scheduling in multi-processor environment, which primarily converts the multi-processor scheduling problem to a set of uni-processor scheduling problem and thereafter uses a uni-pro...
International Workshop on Cellular Nanoscale Networks and their Applications, 2012
Fabrication of the printed memristors and their memristive behavior have been presented for diffe... more Fabrication of the printed memristors and their memristive behavior have been presented for different metal-insulator-metal (MIM) structures. The printing techniques studied for the current work includes electrohydrodynamic printing (EHDP) and roll-to-plate. The materials used for the electrode deposition are silver (Ag) and indium titanium oxide (ITO) while zirconium oxide (ZrO2) and graphene oxide (GO) have been used for the sandwich layer between two electrodes on a polyimide (PI) substrate. Electrically stable bipolar resistive switching behavior of all the MIM structures with significant Off/On ratio has been observed. The analysis regarding device dimensions and its current voltage (IV) behavior with respect to the employed printed electronic techniques confirms their feasibility for the cost-effective memristive device fabrication.
Thin Solid Films, 2013
ABSTRACT Electrohydrodynamic (EHD) printing technique has been deployed to fabricate flexible pri... more ABSTRACT Electrohydrodynamic (EHD) printing technique has been deployed to fabricate flexible printed resistive (memristive) switch in a metal–insulator–metal sandwich structure of Ag/ZrO2/Ag on a polyimide substrate under normal room conditions. The top and bottom electrodes were deposited through the jetting of EHD printing and the active layer of ZrO2 between two electrodes was deposited through the atomization of EHD printing process. The achieved dimensions of the printed device were around 100 μm × 100 μm with the thickness of the bottom electrode, switching layer and top electrode were around 230 nm, 680 nm and 420 nm respectively. The fabricated device showed stable bipolar memristive switching behavior around ± 3 V. The reversible resistive switching behavior was measured with the high OFF/ON ratio of 100:1. The device kept on exhibiting memristive characteristics after being physically flexed over 500 times that shows its viability for flexible electronics applications.
Materials Science in Semiconductor Processing, 2013
In this paper, we have investigated the resistive switching behavior of nanostructured zirconium ... more In this paper, we have investigated the resistive switching behavior of nanostructured zirconium oxide (ZrO 2) thin film deposition by spin coating. The metal (silver) electrodes were patterned by electrohydrodynamic inkjet printing technique. The X-ray diffraction and Fourier transform infra-red spectra confirmed that the presence of monoclinic phase in the as deposited ZrO 2 thin film. The field emission scanning electron microscopic image revealed the uniform deposition of ZrO 2 thin film with spherical morphology. The as-fabricated Ag/ZrO 2 /Ag memory device exhibited the characteristic bipolar resistive switching behavior under consecutive dc sweep. The possible mechanism of the bipolar resistive switching has been discussed in detail. The endurance and retention analysis of the fabricated device revealed the stability of the device. Our results ensure the promising applications of ZrO 2 thin film in the memory device applications.
Microelectronic Engineering, 2013
The insulating active layer has a vital role in the MIM (Metal-Insulator-Metal) structure of resi... more The insulating active layer has a vital role in the MIM (Metal-Insulator-Metal) structure of resistive switch (memristor). Different fabrication technologies are being used to the deposition of the active layer to explore the resistive switching in metal oxides. Electrohydrodynamic atomization (EHDA) has been used in this brief to deposit an active layer for the printed resistive switch (memristor). A thin liquid jet of solution containing ZrO 2 (Zirconium Dioxide) nanoparticles was generated through a metallic capillary with a constant flow rate under the electrical forces. Liquid jet was further disintegrated into small droplets, containing nanoparticles, under the influence of electrical stresses and were collected on the ITO coated PET (Polyethylene Terephthalate) to form uniform layer of ZrO 2 nanoparticles. A smooth thin film was observed with an average thickness of 67 nm. Resistive (memristive) behavior was observed in the deposited thin film with ITO (Indium-Tin Oxide) as a bottom electrode and Ag as a top electrode. Bipolar reversible resistive switching was analyzed by setting different current compliances. Results reveal that EHDA has full potential to fabricate the active layer in resistive switches for printed electronics.
Journal of the Korean Physical Society, 2012
A novel route to thin-film fabrication of graphene oxide (GO) is presented using a well-known tec... more A novel route to thin-film fabrication of graphene oxide (GO) is presented using a well-known technique, i.e., electrospray deposition. For deposition of the graphene-oxide thin film, grapheneoxide ink containing 0.025 wt% graphene oxide flowing through a metal capillary was subjected to a static electric field in order to generate atomized droplets, thereby depositing a uniform thin film of graphene oxide on an indium-tin-oxide coated polyethylene terephthalate substrate. The quality of the layer was characterized by analyzing the surface morphology and the thickness, and the electrical measurements on the single film were performed. In order to study the resistive switching behavior of GO, a prototype GO-based resistive switching device having an active area of 0.026 mm 2 was developed and was analyzed by current voltage measurements. The IV characteristics of the device successfully showed a typical non-volatile resistive switching behavior for a GO layer having the retention times of ∼10 3 s, thus highlighting the electrospray deposition technology as a reliable candidate for the fabrication of GO layers.
Journal of Electronic Materials, 2013
Resistive switching in organic resistive switches fabricated with a sandwich structure of indium ... more Resistive switching in organic resistive switches fabricated with a sandwich structure of indium tin oxide (ITO)-coated polyethylene terephthalate (PET)/ poly(4-vinylphenol) (PVP)/silver (Ag) is reported. A single layer of PVP was used as an active layer in the sandwich structure between the two electrodes. The active layer of the polymer was atomized with the electrohydrodynamic atomization technique on the ITO-coated PET. The film thickness of the PVP polymeric layer on the ITO-coated PET was measured to be 110 nm. The surface morphology was characterized by field-emission scanning electron microscopy, and the purity of the film was examined by x-ray photoelectron spectroscopy analysis. Electrical current-voltage (I-V) measurements confirmed the memristive behavior of the sandwich device. The effect of the current compliance (CC) on resistive switching in the fabricated sandwich structure was also explored. The PVP-based organic resistive switch showed a CC-dependent OFF/ON ratio and memory window. Resistive switching memory effects were prominent at low CC up to nanoamps. The as-fabricated device was operated with low operational voltages for both polarities with OFF/ON ratio greater than 100:1. The robustness of the fabricated memristor was checked with multiple voltage sweeps, and the retention time is reported to be over 100 min.
Japanese Journal of Applied Physics, 2013
ABSTRACT Poly[2-methoxy-5-(2'-ethylhexyloxy)--(p-phenylenevinylene)] (MEH:PPV) based orga... more ABSTRACT Poly[2-methoxy-5-(2'-ethylhexyloxy)--(p-phenylenevinylene)] (MEH:PPV) based organic memristor (memory resistor) has been fabricated on the indium--tin oxide (ITO) coated poly(ethylene terepthalate) (PET) substrate by the electrohydrodynamic atomization (EHDA) technique. Thin jet containing MEH:PPV polymer was generated through a capillary under electrical stresses. The jet was broken into small droplets by adjusting the distance from nozzle to substrate and collected over the substrate under normal room conditions, consequently a high quality layer of MEH:PPV was achieved with an average thickness of 168 nm. The layer was morphologically characterized by a field emission scanning electron microscope (FESEM) analysis. X-ray photoelectron spectroscope (XPS) analysis was also carried out to confirm the chemistry of the deposited material. Electrically, ITO/MEH:PPV/Ag fabricated memristor was found to be switchable between high state and low state between ± 4 V. The research work provides the memristive behavior in electrohydrodynamic atomized layers of MEH:PPV to be used for the next generation printed electronics application.
Applied Physics A, 2013
Polymeric negative differential resistive (NDR) switching was explored based on the sandwiched st... more Polymeric negative differential resistive (NDR) switching was explored based on the sandwiched structure of indium titanium oxide (ITO) coated polyethyleneterepthalate(PET)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/silver(Ag) through electrohydrodynamic atomization (EHDA) printing technique. The NDR switching in the fabricated device with the structure of ITO/PEDOT:PSS/Ag was analyzed through semiconductor device analyzer under polarity dependent bipolar sweeping voltage of less than ±5V${\pm} 5~\mathrm{ V}$. Effect of the current compliance (CC) in the NDR switching of the fabricated switch has been demonstrated. Multiple resistive switching sweeps were taken to scrutinize the robustness of the fabricated device over 100 cycles. The non-volatility of the as-fabricated device was checked against different time stresses over 2500 s. The switching mechanism is proposed to be due to the transition between PEDOT+ and PEDOT0 chains. The current conduction mechanism involved in the PEDOT:PSS based NDR switches is attributed to the ohmic conduction at lower voltages, while space charge limited conduction and NDR effects were prominent due to the injection of carriers at higher voltages.
Journal of the Korean Physical Society, 2012
This brief demonstrates the promising feasibility of electrohydrodynamic (EHD) printing technolog... more This brief demonstrates the promising feasibility of electrohydrodynamic (EHD) printing technology for the fabrication of a crossbar resistive switch (memristor) through the patterning of ITO as a bottom electrode and Ag as a top electrode. An ITO/ZrO2/Ag sandwich exhibiting reversible resistive switching (memristive) behavior has been demonstrated on a glass substrate. A physically layer-wise, electrical current-voltage (IV) characterization was done for the device fabricated using EHD printing. The device dimensions achieved in the current research were around 100 µm × 100 µm. The as-fabricated device showed a high ON/OFF ratio greater than 100000:1 with multiple operational voltages less than ±10 V. The measured retention time of the fabricated device was over 3 days. Results reveal that the current research work provides for the fabrication of a relatively low-cost memristive device with reversible resistive switching properties.
The attributes of a memristor such as non-volatile, simple structure, no leakage current, and fas... more The attributes of a memristor such as non-volatile, simple structure, no leakage current, and fast switching speed have unfolded enormous opportunities for various analog and digital applications. It is imperative to develop an accurate physical model of the memristor in order to design digital applications. The hitherto published memristor modeling approaches do not match with the practical memristor dynamics. A new model is developed by considering Schottky contact at the metal-insulator-metal (MIM) interfaces. In this research work, a novel memristor is also fabricated to validate the proposed model. A bead polymer based on methyl methacrylate and n-butyl methacrylate (MMBM) is firstly used to explore the resistive switching properties of the device. A cost-effective screen printing technique is first demonstrated to deposit the resistive switching layer for the fabrication of the memristor. The resistive switching behavior is observed in the sandwiched layer with a silver (Ag) a...
2019 International Conference on Frontiers of Information Technology (FIT), 2019
People suffering from a neurological injury such as stroke or spinal cord injury can suffer from ... more People suffering from a neurological injury such as stroke or spinal cord injury can suffer from a partial or total loss of their limbs, including hands which can harm their quality of life. It can be countered by the use of prosthetic and robotic support. This article describes the development of a soft wearable robotic glove for stroke-affected patients with limited hand mobility. The developed prototype utilizes Electromyography (EMG) signals that control the system as per the user's intention through actuators. The prototype developed in this work is a cable driven system which eliminates the need of rigid frames and thereby allowing the weight of soft robotic glove to be less than 50 grams and provides flexibility and comfort to the user. The device aims to regulate the grip force of the patient and allows him/her to perform activities of daily life (like grasping a cup) without external help. To enhance the rehabilitation, the robotic glove can also be controlled by another sensor glove that can be worn by the user on their unaffected hand or by a physiotherapist. The glove worn on the affected hand mimics the movement of the sensor glove. The proposed system is cost effective and can be used to handle up to 500 grams of weight. The performance of the glove is evaluated for a stroke affected patients and aged persons to analyze the grip force provided by the device and the range of motion of grip. The results show that the offered assistive strength is sufficient to improve the stroke-affected hand.
Optimized use of computing resources is one of the basic requirements of constrained environments... more Optimized use of computing resources is one of the basic requirements of constrained environments like Internet of Things (IoT). Due to its constrained nature, small computing platforms are frequently used in different IoT solutions. Therefore, optimization of such small platforms can play an important role in an overall improved performance of such solutions. This paper demonstrates an optimized processor utilization by estimating and utilizing the gain time on a small platform. Gain time of a task is defined as the difference between Worst-Case Execution Time (WCET) and its Actual Execution Time (AET) at runtime. It is a practical parameter which is ignored in the theoretical design considerations. Consequently, the offline schedulability analysis of a scheduling algorithm is based only on the WCET which may result tin underutilization of the processing power. In this paper, we present an empirical analysis of the factors affecting the gain time of an application while considering...
Computers & Electrical Engineering, 2018
Reliability, performance and power consumption of a real-time multiprocessor system are negativel... more Reliability, performance and power consumption of a real-time multiprocessor system are negatively affected by high temperatures, spatial gradients and thermal cycles. Software-based load balancing techniques have been used for thermal management. The transfer of workload in such techniques is based on temperature estimation. In this paper, we proposed an online temperatureaware scheduling technique that performs load balancing based on dynamic temperature measurement at a fixed ambient temperature. Contrary to the static techniques that utilize the principle of temperature prediction, the proposed technique does not require any thermal history of workload and is effective for any kind of workload without prior knowledge. Moreover, it reduces the energy consumption and avoids the workload switching delays among the cores. The simulation results show that the technique reduces overall temperature up to 5%, thermal cycles up to 3% and lowers the temporal and spatial gradients compared to the commonly used techniques.
Journal of the Korean Physical Society, 2019
The prediction of the current-voltage (IV) characteristics of resistive switching devices has rem... more The prediction of the current-voltage (IV) characteristics of resistive switching devices has remained a challenge before their physical realization. This research work addresses the prediction of the IV characteristics and the bipolar switching mechanism of polymer-based resistive switches by examining their structures before their fabrication. The research was carried out through an analytical study of the device structure, thereby correlating the predicted IV curve to the in-situ IV characteristics of the device. Different types of the device structures were considered, depending upon the work function of the top and the bottom electrodes and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of the sandwiched layer. We concluded that the defects/traps within the sandwiched layer lead to the interface effect being the dominant switching mechanism driving the polymer-based resistive switches. Furthermore, we also found that the devices following the interface effect are driven from trap-limited space-charge-limited current (SCLC) conduction to trap-free SCLC conduction as their current conduction mechanisms.
International Journal of Distributed Sensor Networks, 2019
Thermal issues in microprocessors have become a major design constraint because of their adverse ... more Thermal issues in microprocessors have become a major design constraint because of their adverse effects on the reliability, performance and cost of the system. This article proposes an improvement in earliest deadline first, a uni-processor scheduling algorithm, without compromising its optimality in order to reduce the thermal peaks and variations. This is done by introducing a factor of fairness to earliest deadline first algorithm, which introduces idle intervals during execution and allows uniform distribution of workload over the time. The technique notably lowers the number of context switches when compare with the previous thermal-aware scheduling algorithm based on the same amount of fairness. Although, the algorithm is proposed for uni-processor environment, it is also applicable to partitioned scheduling in multi-processor environment, which primarily converts the multi-processor scheduling problem to a set of uni-processor scheduling problem and thereafter uses a uni-pro...
International Workshop on Cellular Nanoscale Networks and their Applications, 2012
Fabrication of the printed memristors and their memristive behavior have been presented for diffe... more Fabrication of the printed memristors and their memristive behavior have been presented for different metal-insulator-metal (MIM) structures. The printing techniques studied for the current work includes electrohydrodynamic printing (EHDP) and roll-to-plate. The materials used for the electrode deposition are silver (Ag) and indium titanium oxide (ITO) while zirconium oxide (ZrO2) and graphene oxide (GO) have been used for the sandwich layer between two electrodes on a polyimide (PI) substrate. Electrically stable bipolar resistive switching behavior of all the MIM structures with significant Off/On ratio has been observed. The analysis regarding device dimensions and its current voltage (IV) behavior with respect to the employed printed electronic techniques confirms their feasibility for the cost-effective memristive device fabrication.
Thin Solid Films, 2013
ABSTRACT Electrohydrodynamic (EHD) printing technique has been deployed to fabricate flexible pri... more ABSTRACT Electrohydrodynamic (EHD) printing technique has been deployed to fabricate flexible printed resistive (memristive) switch in a metal–insulator–metal sandwich structure of Ag/ZrO2/Ag on a polyimide substrate under normal room conditions. The top and bottom electrodes were deposited through the jetting of EHD printing and the active layer of ZrO2 between two electrodes was deposited through the atomization of EHD printing process. The achieved dimensions of the printed device were around 100 μm × 100 μm with the thickness of the bottom electrode, switching layer and top electrode were around 230 nm, 680 nm and 420 nm respectively. The fabricated device showed stable bipolar memristive switching behavior around ± 3 V. The reversible resistive switching behavior was measured with the high OFF/ON ratio of 100:1. The device kept on exhibiting memristive characteristics after being physically flexed over 500 times that shows its viability for flexible electronics applications.
Materials Science in Semiconductor Processing, 2013
In this paper, we have investigated the resistive switching behavior of nanostructured zirconium ... more In this paper, we have investigated the resistive switching behavior of nanostructured zirconium oxide (ZrO 2) thin film deposition by spin coating. The metal (silver) electrodes were patterned by electrohydrodynamic inkjet printing technique. The X-ray diffraction and Fourier transform infra-red spectra confirmed that the presence of monoclinic phase in the as deposited ZrO 2 thin film. The field emission scanning electron microscopic image revealed the uniform deposition of ZrO 2 thin film with spherical morphology. The as-fabricated Ag/ZrO 2 /Ag memory device exhibited the characteristic bipolar resistive switching behavior under consecutive dc sweep. The possible mechanism of the bipolar resistive switching has been discussed in detail. The endurance and retention analysis of the fabricated device revealed the stability of the device. Our results ensure the promising applications of ZrO 2 thin film in the memory device applications.
Microelectronic Engineering, 2013
The insulating active layer has a vital role in the MIM (Metal-Insulator-Metal) structure of resi... more The insulating active layer has a vital role in the MIM (Metal-Insulator-Metal) structure of resistive switch (memristor). Different fabrication technologies are being used to the deposition of the active layer to explore the resistive switching in metal oxides. Electrohydrodynamic atomization (EHDA) has been used in this brief to deposit an active layer for the printed resistive switch (memristor). A thin liquid jet of solution containing ZrO 2 (Zirconium Dioxide) nanoparticles was generated through a metallic capillary with a constant flow rate under the electrical forces. Liquid jet was further disintegrated into small droplets, containing nanoparticles, under the influence of electrical stresses and were collected on the ITO coated PET (Polyethylene Terephthalate) to form uniform layer of ZrO 2 nanoparticles. A smooth thin film was observed with an average thickness of 67 nm. Resistive (memristive) behavior was observed in the deposited thin film with ITO (Indium-Tin Oxide) as a bottom electrode and Ag as a top electrode. Bipolar reversible resistive switching was analyzed by setting different current compliances. Results reveal that EHDA has full potential to fabricate the active layer in resistive switches for printed electronics.
Journal of the Korean Physical Society, 2012
A novel route to thin-film fabrication of graphene oxide (GO) is presented using a well-known tec... more A novel route to thin-film fabrication of graphene oxide (GO) is presented using a well-known technique, i.e., electrospray deposition. For deposition of the graphene-oxide thin film, grapheneoxide ink containing 0.025 wt% graphene oxide flowing through a metal capillary was subjected to a static electric field in order to generate atomized droplets, thereby depositing a uniform thin film of graphene oxide on an indium-tin-oxide coated polyethylene terephthalate substrate. The quality of the layer was characterized by analyzing the surface morphology and the thickness, and the electrical measurements on the single film were performed. In order to study the resistive switching behavior of GO, a prototype GO-based resistive switching device having an active area of 0.026 mm 2 was developed and was analyzed by current voltage measurements. The IV characteristics of the device successfully showed a typical non-volatile resistive switching behavior for a GO layer having the retention times of ∼10 3 s, thus highlighting the electrospray deposition technology as a reliable candidate for the fabrication of GO layers.
Journal of Electronic Materials, 2013
Resistive switching in organic resistive switches fabricated with a sandwich structure of indium ... more Resistive switching in organic resistive switches fabricated with a sandwich structure of indium tin oxide (ITO)-coated polyethylene terephthalate (PET)/ poly(4-vinylphenol) (PVP)/silver (Ag) is reported. A single layer of PVP was used as an active layer in the sandwich structure between the two electrodes. The active layer of the polymer was atomized with the electrohydrodynamic atomization technique on the ITO-coated PET. The film thickness of the PVP polymeric layer on the ITO-coated PET was measured to be 110 nm. The surface morphology was characterized by field-emission scanning electron microscopy, and the purity of the film was examined by x-ray photoelectron spectroscopy analysis. Electrical current-voltage (I-V) measurements confirmed the memristive behavior of the sandwich device. The effect of the current compliance (CC) on resistive switching in the fabricated sandwich structure was also explored. The PVP-based organic resistive switch showed a CC-dependent OFF/ON ratio and memory window. Resistive switching memory effects were prominent at low CC up to nanoamps. The as-fabricated device was operated with low operational voltages for both polarities with OFF/ON ratio greater than 100:1. The robustness of the fabricated memristor was checked with multiple voltage sweeps, and the retention time is reported to be over 100 min.
Japanese Journal of Applied Physics, 2013
ABSTRACT Poly[2-methoxy-5-(2'-ethylhexyloxy)--(p-phenylenevinylene)] (MEH:PPV) based orga... more ABSTRACT Poly[2-methoxy-5-(2'-ethylhexyloxy)--(p-phenylenevinylene)] (MEH:PPV) based organic memristor (memory resistor) has been fabricated on the indium--tin oxide (ITO) coated poly(ethylene terepthalate) (PET) substrate by the electrohydrodynamic atomization (EHDA) technique. Thin jet containing MEH:PPV polymer was generated through a capillary under electrical stresses. The jet was broken into small droplets by adjusting the distance from nozzle to substrate and collected over the substrate under normal room conditions, consequently a high quality layer of MEH:PPV was achieved with an average thickness of 168 nm. The layer was morphologically characterized by a field emission scanning electron microscope (FESEM) analysis. X-ray photoelectron spectroscope (XPS) analysis was also carried out to confirm the chemistry of the deposited material. Electrically, ITO/MEH:PPV/Ag fabricated memristor was found to be switchable between high state and low state between ± 4 V. The research work provides the memristive behavior in electrohydrodynamic atomized layers of MEH:PPV to be used for the next generation printed electronics application.
Applied Physics A, 2013
Polymeric negative differential resistive (NDR) switching was explored based on the sandwiched st... more Polymeric negative differential resistive (NDR) switching was explored based on the sandwiched structure of indium titanium oxide (ITO) coated polyethyleneterepthalate(PET)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/silver(Ag) through electrohydrodynamic atomization (EHDA) printing technique. The NDR switching in the fabricated device with the structure of ITO/PEDOT:PSS/Ag was analyzed through semiconductor device analyzer under polarity dependent bipolar sweeping voltage of less than ±5V${\pm} 5~\mathrm{ V}$. Effect of the current compliance (CC) in the NDR switching of the fabricated switch has been demonstrated. Multiple resistive switching sweeps were taken to scrutinize the robustness of the fabricated device over 100 cycles. The non-volatility of the as-fabricated device was checked against different time stresses over 2500 s. The switching mechanism is proposed to be due to the transition between PEDOT+ and PEDOT0 chains. The current conduction mechanism involved in the PEDOT:PSS based NDR switches is attributed to the ohmic conduction at lower voltages, while space charge limited conduction and NDR effects were prominent due to the injection of carriers at higher voltages.
Journal of the Korean Physical Society, 2012
This brief demonstrates the promising feasibility of electrohydrodynamic (EHD) printing technolog... more This brief demonstrates the promising feasibility of electrohydrodynamic (EHD) printing technology for the fabrication of a crossbar resistive switch (memristor) through the patterning of ITO as a bottom electrode and Ag as a top electrode. An ITO/ZrO2/Ag sandwich exhibiting reversible resistive switching (memristive) behavior has been demonstrated on a glass substrate. A physically layer-wise, electrical current-voltage (IV) characterization was done for the device fabricated using EHD printing. The device dimensions achieved in the current research were around 100 µm × 100 µm. The as-fabricated device showed a high ON/OFF ratio greater than 100000:1 with multiple operational voltages less than ±10 V. The measured retention time of the fabricated device was over 3 days. Results reveal that the current research work provides for the fabrication of a relatively low-cost memristive device with reversible resistive switching properties.