Recent Submissions

  • Enhanced photo-response of WS2 photodetectors through interfacial defect engineering using TiO2 interlayer

    Pak, Yusin; Park, Woojin; Alaal, Naresh; Kumaresan, Yogeenth; Aravindh, S. Assa; Mitra, Somak; Xin, Bin; Min, Jung-Wook; Kim, Hyeonghun; Lim, Namsoo; Cho, Byungjin; Jung, Gun Young; Hussain, Muhammad Mustafa; Roqan, Iman S. (ACS Applied Electronic Materials, American Chemical Society (ACS), 2020-02-26) [Article]
    To develop a stable and reliable two-dimensional (2D) tungsten disulfide (WS2)-based photodetector (PD), it is essential to address the issue of interfacial defects that are unavoidably formed at an interface between WS2 and metal contact, as such defects can markedly deteriorate photo-response characteristics. In this work, this drawback is mitigated by adopting a facile technique for passivating a WS2 surface with an ultrathin TiO2 film. The TiO2 interlayer is deposited on the 2D-WS2 surface via twenty cycles of atomic layer deposition (ALD) prior to proceeding with photolithography and contact metal deposition. Advanced characterizations reveal that TiO2/WS2 PD exhibits enhanced photo-response compared to bare WS2. Much higher photo-responsivity (~10 times higher at 1 mW/cm2) and faster recovery (~124 times faster at 0.1 V) is obtained from TiO2/WS2 PDs relative to bare WS2 PDs. The mechanism underlying the enhanced PD performance is faithfully demonstrated. The computational density functional theory (DFT) using Hyed-Scuseria-Ernzerhof (HSE) approach demonstrates the significant role of TiO2/WS2 interface in facilitating the charge transfer, and improving the PD performance compared to the bare device. This approach paves the way for developing reliable and high-performance 2D WS2-based optoelectronic devices.
  • Design Analysis and Human Tests of Foil-Based Wheezing Monitoring System for Asthma Detection

    Khan, Sherjeel M.; Qaiser, Nadeem; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (IEEE Transactions on Electron Devices, IEEE, 2019-12-30) [Article]
    We present a flexible acoustic sensor that has been designed to detect wheezing (a common symptom of asthma) while attached to the chest of a human. We adopted a parallel-plate capacitive structure using air as the dielectric material. The pressure (acoustic) waves from wheezing vibrate the top diaphragm of the structure, thereby changing the output capacitance. The sensor is designed in such a way that it resonates in the frequency range of wheezing (100-1000 Hz), which presents twofold benefits. The resonance results in large deflection of the diaphragm that eradicates the need for using signal amplifiers (used in microphones). Second, the design itself acts as a low-pass filter to reduce the effect of background noise, which mostly lies in the >1000-Hz frequency range. The resulting analog interface is minimal, and thus consumes less power and occupies less space. The sensor is made up of low-cost sustainable materials (aluminum foil) that greatly reduce the cost and complexity of manufacturing processes. A robust wheezing detection (matched filter) algorithm is used to identify different types of wheezing sounds among the noisy signals originating from the chest that lie in the same frequency range as wheezing. The sensor is connected to a smartphone via Bluetooth, enabling signal processing and further integration into digital medical electronic systems based on the Internet of Things (IoT). Bending, cyclic pressure, heat, and sweat tests are performed on the sensor to evaluate its performance in simulated real-life harsh conditions.
  • In-plane deformation mechanics of highly stretchable Archimedean interconnects

    Alcheikh, Nouha; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (AIP Advances, AIP Publishing, 2019-01-24) [Article]
    Stretchable inorganic electronics are very attractive for many applications, which require large deformation during stretching. Archimedean–inspired interconnect designs can offer and achieve high level of stretchability under extreme deformations. Here, we systematically investigate the relationship between stretchability and the geometrical parameters under in-plane deformation. The stretchable structures are made of amorphous silicon (a-Si), which cracked at very small strain 1.6%. Finite element method (FEM) was carried out to simulate the maximum strain/stress of interconnects. The results show that high stress appears at the base and the half-circle of the Archimedean interconnects. Experimental results agree well with the numerical modeling, both showing that the stretchability more than double when the straight line at the base is replaced by two lines in series. Our results demonstrate a stretchability up to 1020% and 605%, respectively for two types of Archimedean interconnect. The results indicate that the narrower width, the larger gap separated the straight lines (higher radius), and the longer straight lines will achieve lower stress and high stretchability. Further, a numerical study is conducted to explore the mechanical performance of Poly-crystalline silicon based structures where the maximum bending strain should be up to 1%.
  • Corrugation Architecture Enabled Ultra-Flexible Mono-Crystalline Silicon Solar Cells via Plasma Etching and Laser Ablation

    Bahabry, Rabab R.; Sepulveda, Adrian C.; Kutbee, Arwa T.; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC), Institute of Electrical and Electronics Engineers (IEEE), 2018-12-08) [Conference Paper]
    Extreme mechanical flexibility is highly desirable for the new generation of Mono-Crystalline Silicon solar cells while maintaining the high power conversion efficiency. Here, we show a novel corrugation architecture, which transforms rigid interdigitated back contact 5 ×5 inch c-Si solar wafers into an ultra-flexible (140 m bending radius) version while retaining its original efficiency of 17%. We also investigated using both fluorine-based plasma and Ytterbium fiber laser for forming the corrugation architecture.
  • Fully spherical stretchable silicon photodiodes array for simultaneous 360 imaging

    Sevilla, Galo T.; Qaiser, Nadeem; Diaz, Marlon; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (Applied Physics Letters, AIP Publishing, 2018-09-26) [Article]
    Imaging is one of the important wonders of today's world. While everyday millions of snaps are taken, new advances like panoramic imaging have become increasingly popular. However, as of today an imaging system which can simultaneously capture images from all 360° viewpoints with a single sensor has not been achieved. Here, we show a physically flexible and stretchable version of arrayed silicon photodiodes made from low-cost bulk monocrystalline silicon (100) that can capture simultaneous omnidirectional images. The present report, with multiple wavelength detection, fast photoresponsivity, a wide viewing angle, selective aberration, and dynamic focusing enabled by 3D printed pneumatic actuators (note, today millions of image sensors can be integrated in mm area), overcomes previous demonstrations of only hemispherical photodetection capability. Such imaging capability will make unmanned air vehicles or self-driven cars safer, affordable augmented and virtual reality and more importantly, in-vivo biomedical imaging will be more effective.
  • Ultra-stretchable Archimedean interconnects for stretchable electronics

    Alcheikh, Nouha; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (Extreme Mechanics Letters, Elsevier BV, 2018-08-20) [Article]
    Stretchable inorganic electronic systems are promising research area for many applications, such as wearable electronics. The island-interconnects design represents one of the categories, which is widely used in stretchable electronics. Here we show, Archimedean-inspired design for interconnect that can achieve more than 1020 % of stretchability. Mathematical modeling followed by experimental validation is done to study the relationship between the stretchability and various geometrical parameters. Further, a numerical study is conducted comparing the stretchability of the Archimedean structure to that of the spiral and serpentine structures. We show that the Archimedean interconnects attain the lowest stress and thus the highest stretchability.
  • Strain-induced topological transformation of thermoelectric responsive thin films

    Singh, Devendra; Hussain, Muhammad Mustafa (2018-06-07) [Patent]
    A three-dimensional structure may be obtained from a two-dimensional thin film by applying a stressor layer to the two-dimensional thin film and releasing the thin film from a support substrate. Such a three-dimensional structure may include a thermoelectric responsive material for forming a thermoelectric generator (TEG). A manufacturing process for the transformation from 2-D to 3-D may use a polymer stressor layer deposited on the thermoelectric responsive thin film. The combination thermoelectric responsive layer and stressor layer can be released from a carrier, after which the stressor layer causes the thermoelectric responsive layer to curl. The curl can cause the thermoelectric responsive layer to roll up during the release from the carrier to form a tubular structure.
  • CMOS Enabled Microfluidic Systems for Healthcare Based Applications

    Khan, Sherjeel; Gumus, Abdurrahman; Nassar, Joanna M.; Hussain, Muhammad Mustafa (Advanced Materials, Wiley, 2018-02-27) [Article]
    With the increased global population, it is more important than ever to expand accessibility to affordable personalized healthcare. In this context, a seamless integration of microfluidic technology for bioanalysis and drug delivery and complementary metal oxide semiconductor (CMOS) technology enabled data-management circuitry is critical. Therefore, here, the fundamentals, integration aspects, and applications of CMOS-enabled microfluidic systems for affordable personalized healthcare systems are presented. Critical components, like sensors, actuators, and their fabrication and packaging, are discussed and reviewed in detail. With the emergence of the Internet-of-Things and the upcoming Internet-of-Everything for a people-process-data-device connected world, now is the time to take CMOS-enabled microfluidics technology to as many people as possible. There is enormous potential for microfluidic technologies in affordable healthcare for everyone, and CMOS technology will play a major role in making that happen.
  • Democratized electronics to enable smart living for all

    Hussain, Muhammad Mustafa; Nassar, Joanna M.; Khan, S. M.; Saikh, S. F.; Sevilla, Galo T.; Kutbee, Arwa T.; Bahabry, Rabab R.; Babatain, Wedyan; Muslem, A. S.; Nour, Maha A.; Wicaksono, I.; Mishra, Kush (2017 IEEE SENSORS, Institute of Electrical and Electronics Engineers (IEEE), 2018-01-02) [Conference Paper]
    With the increased global population, smart living is an increasingly important criteria to ensure equal opportunities for all. Therefore, what is Smart Living? The first time when we tossed this terminology seven years back, we thought reducing complexities in human life. Today we believe it more. However, smart living for all complicates the technological need further. As by all, we mean any age group, any academic background and any financial condition. Although electronics are powerful today and have enabled our digital world, many as of today have not experienced that progress. Going forward while we realize more and more electronics in our daily life, the most important question would be how. Here we show, a heterogeneous integration approach to integrate low-cost high performance interactive electronic system which are physically compliant. We are redesigning electronics to redefine its purposes to reconfigure life for all to enable smart living.
  • Corrugation Architecture Enabled Ultraflexible Wafer-Scale High-Efficiency Monocrystalline Silicon Solar Cell

    Bahabry, Rabab R.; Kutbee, Arwa T.; Khan, Sherjeel M.; Sepulveda, Adrian C.; Wicaksono, Irmandy; Nour, Maha A.; Wehbe, Nimer; Almislem, Amani Saleh Saad; Ghoneim, Mohamed T.; Sevilla, Galo T.; Syed, Ahad; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (Advanced Energy Materials, Wiley, 2018-01-02) [Article]
    Advanced classes of modern application require new generation of versatile solar cells showcasing extreme mechanical resilience, large-scale, low cost, and excellent power conversion efficiency. Conventional crystalline silicon-based solar cells offer one of the most highly efficient power sources, but a key challenge remains to attain mechanical resilience while preserving electrical performance. A complementary metal oxide semiconductor-based integration strategy where corrugation architecture enables ultraflexible and low-cost solar cell modules from bulk monocrystalline large-scale (127 × 127 cm) silicon solar wafers with a 17% power conversion efficiency. This periodic corrugated array benefits from an interchangeable solar cell segmentation scheme which preserves the active silicon thickness of 240 μm and achieves flexibility via interdigitated back contacts. These cells can reversibly withstand high mechanical stress and can be deformed to zigzag and bifacial modules. These corrugation silicon-based solar cells offer ultraflexibility with high stability over 1000 bending cycles including convex and concave bending to broaden the application spectrum. Finally, the smallest bending radius of curvature lower than 140 μm of the back contacts is shown that carries the solar cells segments.
  • Enhanced Performance of MoS2 Photodetectors by Inserting an ALD-Processed TiO2 Interlayer

    Pak, Yusin; Park, Woojin; Mitra, Somak; Devi, Assa Aravindh Sasikala; Loganathan, Kalaivanan; Kumaresan, Yogeenth; Kim, Yonghun; Cho, Byungjin; Jung, Gun-Young; Hussain, Muhammad Mustafa; Roqan, Iman S. (Small, Wiley, 2017-12-04) [Article]
    2D molybdenum disulfide (MoS2) possesses excellent optoelectronic properties that make it a promising candidate for use in high-performance photodetectors. Yet, to meet the growing demand for practical and reliable MoS2 photodetectors, the critical issue of defect introduction to the interface between the exfoliated MoS2 and the electrode metal during fabrication must be addressed, because defects deteriorate the device performance. To achieve this objective, the use of an atomic layer-deposited TiO2 interlayer (between exfoliated MoS2 and electrode) is reported in this work, for the first time, to enhance the performance of MoS2 photodetectors. The TiO2 interlayer is inserted through 20 atomic layer deposition cycles before depositing the electrode metal on MoS2/SiO2 substrate, leading to significantly enhanced photoresponsivity and response speed. These results pave the way for practical applications and provide a novel direction for optimizing the interlayer material.
  • Strain-Induced Rolled Thin Films for Lightweight Tubular Thermoelectric Generators

    Singh, Devendra; Kutbee, Arwa T.; Ghoneim, Mohamed T.; Hussain, Aftab M.; Hussain, Muhammad Mustafa (Advanced Materials Technologies, Wiley, 2017-11-24) [Article]
    Thermoelectric generators (TEGs) are interesting energy harvesters of otherwise wasted heat. Here, a polymer-assisted generic process and its mechanics to obtain sputtered thermoelectric (TE) telluride material-based 3D tubular structures with unprecedented length (up to seamless 4 cm and further expandable) are shown. This length allows for large temperature differences between the hot and the cold ends, a critical but untapped enabler for high power generation. Compared with a flat slab, better area efficiency is observed for a rolled tube and compared with a solid rod architecture, a rolled tube uses less material (thus making it lightweight and cost effective) and has competitive performance advantage due to a smaller contact area. It is also shown that a tubular architecture thermopile-based TEG is able to generate up to 5 μW of power (eight pairs of p- and n-type thermopiles) through a temperature difference of 60 °C. The demonstrated process can play an important role in transforming 2D atomic crystal structure TE materials into 3D tubular thermopiles for effective TEG application, which can maintain higher temperature differences by longer distances between hot and cold ends.
  • Mechanical response of spiral interconnect arrays for highly stretchable electronics

    Qaiser, Nadeem; Khan, S. M.; Nour, Maha A.; Rehman, M. U.; Rojas, J. P.; Hussain, Muhammad Mustafa (Applied Physics Letters, AIP Publishing, 2017-11-21) [Article]
    A spiral interconnect array is a commonly used architecture for stretchable electronics, which accommodates large deformations during stretching. Here, we show the effect of different geometrical morphologies on the deformation behavior of the spiral island network. We use numerical modeling to calculate the stresses and strains in the spiral interconnects under the prescribed displacement of 1000 μm. Our result shows that spiral arm elongation depends on the angular position of that particular spiral in the array. We also introduce the concept of a unit-cell, which fairly replicates the deformation mechanism for full complex hexagon, diamond, and square shaped arrays. The spiral interconnects which are axially connected between displaced and fixed islands attain higher stretchability and thus experience the maximum deformations. We perform tensile testing of 3D printed replica and find that experimental observations corroborate with theoretical study.
  • Wavy Architecture Thin-Film Transistor for Ultrahigh Resolution Flexible Displays

    Hanna, Amir; Kutbee, Arwa T.; Subedi, Ram Chandra; Ooi, Boon S.; Hussain, Muhammad Mustafa (Small, Wiley, 2017-11-13) [Article]
    A novel wavy-shaped thin-film-transistor (TFT) architecture, capable of achieving 70% higher drive current per unit chip area when compared with planar conventional TFT architectures, is reported for flexible display application. The transistor, due to its atypical architecture, does not alter the turn-on voltage or the OFF current values, leading to higher performance without compromising static power consumption. The concept behind this architecture is expanding the transistor's width vertically through grooved trenches in a structural layer deposited on a flexible substrate. Operation of zinc oxide (ZnO)-based TFTs is shown down to a bending radius of 5 mm with no degradation in the electrical performance or cracks in the gate stack. Finally, flexible low-power LEDs driven by the respective currents of the novel wavy, and conventional coplanar architectures are demonstrated, where the novel architecture is able to drive the LED at 2 × the output power, 3 versus 1.5 mW, which demonstrates the potential use for ultrahigh resolution displays in an area efficient manner.
  • Flexible and biocompatible high-performance solid-state micro-battery for implantable orthodontic system

    Kutbee, Arwa T.; Bahabry, Rabab R.; Alamoudi, Kholod; Ghoneim, Mohamed T.; Diaz, Marlon; Almislem, Amani Saleh Saad; Gumus, Abdurrahman; Diallo, Elhadj; Nassar, Joanna M.; Hussain, Aftab M.; Khashab, Niveen M.; Hussain, Muhammad Mustafa (npj Flexible Electronics, Springer Nature, 2017-10-25) [Article]
    To augment the quality of our life, fully compliant personalized advanced health-care electronic system is pivotal. One of the major requirements to implement such systems is a physically flexible high-performance biocompatible energy storage (battery). However, the status-quo options do not match all of these attributes simultaneously and we also lack in an effective integration strategy to integrate them in complex architecture such as orthodontic domain in human body. Here we show, a physically complaint lithium-ion micro-battery (236 μg) with an unprecedented volumetric energy (the ratio of energy to device geometrical size) of 200 mWh/cm3 after 120 cycles of continuous operation. Our results of 90% viability test confirmed the battery’s biocompatibility. We also show seamless integration of the developed battery in an optoelectronic system embedded in a three-dimensional printed smart dental brace. We foresee the resultant orthodontic system as a personalized advanced health-care application, which could serve in faster bone regeneration and enhanced enamel health-care protection and subsequently reducing the overall health-care cost.
  • Modular Lego-Electronics

    Shaikh, Sohail F.; Ghoneim, Mohamed T.; Bahabry, Rabab R.; Khan, Sherjeel M.; Hussain, Muhammad Mustafa (Advanced Materials Technologies, Wiley, 2017-10-24) [Article]
    Electronic system components have thousands of individual field effect transistors (FETs) interconnected executing dedicated functions. Assembly yield of >80% will guarantee system failure since a single interconnect failure will result in undesired performance. Hence, a paradigm shift is needed in the self-assembly or integration of state-of-the-art integrated circuits (ICs) for a physically compliant system. Traditionally, most ICs share same geometry with only variations in dimensions and packaging. Here, a generic manufacturable method of converting state-of-the-art complementary metal oxide semiconductor-based ICs into modular Lego-electronics is shown with unique geometry that is physically identifiable to ease manufacturing and enhance throughput. Various geometries at the backside of the silicon die and on the destination site having the same geometry with relaxed dimension (up to 50 µm extra) allow targeted site binding like DNA assembly. Different geometries, angles, and heights for different modules provide a unique identity to each of the ICs. A two-level geometric combination presented here helps in maintaining the uniqueness of individual module to assemble at exact matching site like a perfect lock-and-key model. The assembled ICs offer uncompromised electrical performance, higher yield, and fabrication ease. In future, this method can further be expanded for fluidic assisted self-assembly.
  • Nano-islands Based Charge Trapping Memory: A Scalability Study

    Elatab, Nazek; Saadat, Irfan; Saraswat, Krishna; Nayfeh, Ammar (IEEE Transactions on Nanotechnology, Institute of Electrical and Electronics Engineers (IEEE), 2017-10-19) [Article]
    Zinc-oxide (ZnO) and zirconia (ZrO2) metal oxides have been studied extensively in the past few decades with several potential applications including memory devices. In this work, a scalability study, based on the ITRS roadmap, is conducted on memory devices with ZnO and ZrO2 nano-islands charge trapping layer. Both nano-islands are deposited using atomic layer deposition (ALD), however, the different sizes, distribution and properties of the materials result in different memory performance. The results show that at the 32-nm node charge trapping memory with 127 ZrO2 nano-islands can provide a 9.4 V memory window. However, with ZnO only 31 nano-islands can provide a window of 2.5 V. The results indicate that ZrO2 nano-islands are more promising than ZnO in scaled down devices due to their higher density, higher-k, and absence of quantum confinement effects.
  • Stable MoS2 Field-Effect Transistors Using TiO2 Interfacial Layer at Metal/MoS2 Contact

    Park, Woojin; Min, Jung-Wook; Shaikh, Sohail F.; Hussain, Muhammad Mustafa (physica status solidi (a), Wiley, 2017-09-07) [Article]
    Molybdenum disulphide (MoS2) is an emerging 2-dimensional (2D) semiconductor for electronic devices. However, unstable and low performance of MoS2 FETs is an important concern. In this study, inserting an atomic layer deposition (ALD) titanium dioxide (TiO2) interfacial layer between contact metal and MoS2 channel is suggested to achieve more stable performances. The reduced threshold voltage (VTH) shift and reduced series resistance (RSD) were simultaneously achieved.
  • Neuron-inspired flexible memristive device on silicon (100)

    Ghoneim, Mohamed T.; Hussain, Muhammad Mustafa (arXiv, 2017-06-18) [Preprint]
    Comprehensive understanding of the world's most energy efficient powerful computer, the human brain, is an elusive scientific issue. Still, already gained knowledge indicates memristors can be used as a building block to model the brain. At the same time, brain cortex is folded allowing trillions of neurons to be integrated in a compact volume. Therefore, we report flexible aluminium oxide based memristive devices fabricated and then derived from widely used bulk mono-crystalline silicon (100). We use complementary metal oxide semiconductor based processes to layout the foundation for ultra large scale integration (ULSI) of such memory devices to advance the task of comprehending a physical model of human brain.
  • Stretchable and foldable silicon-based electronics

    Cavazos Sepulveda, Adrian; Diaz Cordero, M. S.; Carreno, Armando Arpys Arevalo; Nassar, Joanna M.; Hussain, Muhammad Mustafa (Applied Physics Letters, AIP Publishing, 2017-03-30) [Article]
    Flexible and stretchable semiconducting substrates provide the foundation for novel electronic applications. Usually, ultra-thin, flexible but often fragile substrates are used in such applications. Here, we describe flexible, stretchable, and foldable 500-μm-thick bulk mono-crystalline silicon (100) “islands” that are interconnected via extremely compliant 30-μm-thick connectors made of silicon. The thick mono-crystalline segments create a stand-alone silicon array that is capable of bending to a radius of 130 μm. The bending radius of the array does not depend on the overall substrate thickness because the ultra-flexible silicon connectors are patterned. We use fracture propagation to release the islands. Because they allow for three-dimensional monolithic stacking of integrated circuits or other electronics without any through-silicon vias, our mono-crystalline islands can be used as a “more-than-Moore” strategy and to develop wearable electronics that are sufficiently robust to be compatible with flip-chip bonding.

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