Multiterminal Memristive Nanowire Devices for Logic and Memory Applications: A Review

Memristive devices have the potential for a complete renewal of the electron devices landscape, including memory, logic, and sensing applications. This is especially true when considering that the memristive functionality is not limited to two-terminal devices, whose practical realization has been demonstrated within a broad range of different technologies. For electron devices, the memristive functionality can be generally attributed to a material state modification, whose dynamics can be engineered to target a specific application. In this review paper, we show that trap charging dynamics can explain some of the memristive effects previously reported for Schottky-barrier field-effect Si nanowire transistors (SB SiNW FETs). Moreover, the SB SiNW FETs do show additional memristive functionality due to trap charging at the metal/ semiconductor surface. The combination of these two memristive effects into multiterminal metal–oxide–semiconductor field-effect transistor (MOSFET) devices gives rise to new opportunities for both memory and logic applications as well as new sensors based on the physical mechanism that originate memristance. In the special case of four-terminal memristive Si nanowire devices, which are presented for the first time in this paper, enhanced functionality is demonstrated. Finally, the multiterminal memristive devices presented here have the potential of a very high integration density, and they are suitable for hybrid complementary metal–oxide–semiconductor (CMOS) cofabrication with a CMOS-compatible process

Applications of Multi-Terminal Memristive Devices: A Review

Memristive devices have the potential for a complete renewal of the electron devices landscape, including memory, logic and sensing applications. This is especially true when considering that the memristive functionality is not limited to two-terminal devices, whose practical realization has been demonstrated within a broad range of different technologies. For electron devices, the memristive functionality can be generally attributed to a state modification, whose dynamics can be engineered to target a specific application. In this review paper, we show examples of two-terminal Resistive RAMs (ReRAM) for standalone memory and Field Programmable Gate Arrays (FPGA) applications. Moreover, a Generic Memory Structure (GMS) utilizing two ReRAMs for 3D-FPGA is discussed. In addition, we show that trap charging dynamics can explain some of the memristive effects previously reported for Schottky-barrier field-effect Si nanowire transistors (SB SiNW FETs). Moreover, the SB SiNW FETs do show additional memristive functionality due to trap charging at the metal/semiconductor surface. The combination of these two memristive effects into multi-terminal MOSFET devices gives rise to new opportunities for both memory and logic applications as well as new sensors based on the physical mechanism that originate memristance. Finally, the multi-terminal memristive devices presented here have the potential of a very high integration density, and they are suitable for hybrid CMOS co-fabrication with a CMOS-compatible process

Memristive-Biosensors: A New Detection Method by Using Nanofabricated Memristors

This paper proposes a new detection methodology based on memristive-effect registered on silicon nanowire. The nano-wires are fabricated by a lithographic technique that allows precise and selective etching at the nanoscale. The wires are obtained in three main steps. Initially, a photoresist line defines the wire position. In a second step, silicon deep reactive ion etching is performed to obtain a scalloped trench. In the final step, the trench is reduced to a suspended nanowire after wet oxidation. The obtained wires present Schottky barrier contacts and are used for bio-molecular detection on dried samples. The memristive silicon nanowire devices are functionalized with rabbit antibodies in order to sense antigens. The sensitivity and detection limit of this new kind of nano-bio-sensors are estimated equal to 37 ± 1 mV/fM and 3.4 ± 1.8 fM, respectively

SiNW-based Biosensors for Profiling Biomarkers in Breast Tumor Tissues

Breast cancer is the most common life-threatening malignancy in women of most developed countries today, with approximately 200,000 new cases diagnosed every year. About 30% of these cases progress to metastatic disease and death. Considering that one-third of these cancer deaths could be decreased if detected and treated early, new strategies for early breast cancer detection are needed to improve the efficacy of current diagnostics. The sensitive analysis of proteins such as breast cancer biomarkers has become the focus of intensive research due to its relevance to tumor diagnosis. However, the state-of-the-art diagnostic tools still lack the level of resolution needed for the detection of biomarkers at the very early stage of the disease, when treatments have more probability of success, and when protein concentration in tumor tissue is still very low. Nanotechnologies have shown great potential for the development of high-sensitive, portable devices for clinical applications. In particular, SiNWs with their unique properties such as the high surface-to-volume ratio and size, combined with the specificity of immune-sensing, are natural candidates for the fabrication of nanosensors. Thanks to their compatibility with conventional CMOS technology, SiNWs have been incorporated in standard FETs. In biosensing, SiNW-FETs have been shown a promising method for the label-free detection of trace amounts of biomolecules. However, detection of Antigen using Antibody immobilized SiNW-FETs is limited by ionic screening effects that reduce the sensor responsiveness and limit their applicability in tumor tissue. Here, we propose novel SiNW-based biosensing strategies with the aim of overcoming current sensitivity limitations of conventional SiNW-FET biosensors for the detection of breast cancer biomarkers in real human samples. Specifically, we address this goal by investigating two different approaches of biosensing. In the first method, we push the sensitivity of SiNW-FETs to their limits by proposing an alternative way of doing sensing in dry conditions. We show that in-air electrical measurements of Ab-Ag binding have the big advantage of increased Debye screening length in non-bulk solutions, and enable highly sensitive and specific measurements in breast tumor extract. Then, we present a completely novel biosensing paradigm that shows, for the first time, the use of memristive effects in fabricated SiNWs for biodetection purposes. This novel detection method has been named Voltage Gap (VoG)-biosensing as it is based on the changes of the VoG parameter, observed in the hysteretic characteristic of memristive devices, as a function of biomolecules. In this research, we demonstrate the use of the memristive-based VoG effect in Schottky Barrier SiNWs for the high-resolution sensing of ionic and biological species both in ideal buffer solutions and in tumor tissue extracts. Moreover, we propose an original theory enabling the physical interpretation and prediction of the mechanisms underlying the VoG-biosensing method in memristive devices. Finally, we demonstrate the potential of our system for future integration in a multi-panel VoG-biosensing platform. We fabricated a PDMS microfluidics enabling selective and high-quality functionalization of the NWs. We also realized a CMOS readout circuit for multiplexed VoG acquisition. The simulations demonstrate the feasibility of the approach and the potential for the integration of the reader with a portable and automated biosensing platform. Microfluidics and VoG reader will enable fast, concurrent detection ofmultiple angiogenic and inflammatory ligands in tumor tissue. This will highly improve the level of knowledge of the cancer disease by capturing the heterogeneity and the complexity of the tumor microenvironment, thus leading to novel opportunities in breast cancer diagnosis

Memristive Devices Fabricated with Silicon Nanowire Schottky Barrier Transistors

This paper reports on the memory and memristive effects of Schottky barrier field effect transistors (SBFET) with gate-all-around (GAA) configuration and Si nanowire (SiNW) channel. Similar behavior has also been investigated for SBFETs with poly-Si nanowire (poly-SiNW) channel in back-gate configuration. The memristive devices presented here have the potential of a very high integration density, and they are suitable for hybrid CMOS co-fabrication with a CMOS-compatible process. We show that 2 different regimes are possible, making these devices suitable either for volatile ambipolar memory or resistive random access memory (RRAM) applications. In addition, frequency- and amplitude- dependence of the memristive behavior are reported

Reconfigurable Si Nanowire Nonvolatile Transistors

Reconfigurable transistors merge unipolar p- and n-type characteristics of field-effect transistors into a single programmable device. Combinational circuits have shown benefits in area and power consumption by fine-grain reconfiguration of complete logic blocks at runtime. To complement this volatile programming technology, a proof of concept for individually addressable reconfigurable nonvolatile transistors is presented. A charge-trapping stack is incorporated, and four distinct and stable states in a single device are demonstrated

Modeling Memristive Biosensors

In the present work, a computational study is carried out investigating the relationship between the biosensing and the electrical characteristics of two-terminal Schottky- barrier silicon nanowire devices. The model suggested successfully reproduces computationally the experimentally obtained electrical behavior of the devices prior to and after the surface bio-modification. Throughout modeling and simulations, it is confirmed that the nanofabricated devices present electrical behavior fully equivalent to that of a memristor device, according to literature. Furthermore, the model introduced successfully reproduces computationally the voltage gap appearing in the current to voltage characteristics for nanowire devices with bio- modified surface. Overall, the present study confirms the implication of the memristive effect for bio sensing applications, therefore demonstrating the Memristive Biosensors