Nano-FET Devices: Miniaturization, Simulation, and Applications (Part 2)

In the semiconductor industry, the integration of the Complementary-Metal-Oxide-Semiconductor (CMOS) mechanism into Integrated Circuits (ICs) has resulted in a significant rise in the count of transistors on a single chip. This is made possible by shrinking down the size of Metal-Oxide-Semiconductor-Field-Effect-Transistors (MOSFETs). However, scaling can lead to device performance degradation. To address this, advanced MOSFET designs like multi-gate transistors, junction-less transistors, and Tunnel FETs have been proposed, aiming to sustain Moore's Law and support continued transistor scaling in the coming decade. The key principles of this chapter involved in both single and multi-gate FETs include quantum mechanics, carrier transport, and electrostatics. The scaling of transistors to smaller sizes involves considerations of quantum effects, like tunneling and quantum confinement, which have a significant impact on their behavior. Understanding this chapter is crucial for optimizing their performance, enabling further miniaturization, and enhancing the capabilities of integrated circuits. Additionally, it plays a crucial role in advancing the field of nextgeneration electronics and computational devices.

In the last few years, the semiconductor industry has brought about a drastic revolution in the existing technology in order to realize a larger on-chip integration, enhance performance, increase operating speed, and decrease energy consumption. Delay and power consumption have become the most vital performance parameters of any digital circuit. One of the methods devised to achieve this is by scaling the feature size of a transistor. However, when the channel length is reduced beyond 45nm in metal-oxidesemiconductor field-effect transistors (MOSFETs) technology, it gives rise to perilous complications and challenges such as decreased gate control, short channel effect, increased power density, higher sensitivity to process deviation, higher manufacturing cost, and increased leakage current. This draws a limit on the transistor size and demands for new transistor structures and technologies to overcome the drawbacks. Technologies like benzene rings, single electron transistors (SET), Quantum-dot cellular automata (QCA), and carbon nanotubes are slowly rising as alternatives to reduce the problems associated with CMOS. New technologies demand faster processors, smaller sizes, and less power consumption. Advances in 5G networks have increased the pressure to improve the battery life of smartphones, their performance, spectral efficiency, and many more. The potential to achieve these is the use of Carbon Nanotube Field Effect Transistors (CNTFETs). They have higher carrier mobilities and direct band gaps that enhance the band-to-band tunneling and optical properties. These features make CNTFETs suitable to be used in future novel electronic devices. Hence, this chapter focuses on the emerging and future trends of CNTFETs. The constructional aspects, features, types, designs, and applications of CNTFETs are dealt with in detail in the forthcoming sections of the chapter.

Carbon Nanotube Field Effect Transistors (CNTFETs) are potential nanoscaled devices for realising high-performance, very dense, and low-power circuits. A Carbon Nanotube Field Effect Transistor is a FET that uses a single CNT or an array of CNTs as the channel material rather than bulk silicon as in a standard MOSFET configuration. A carbon nanotube is at the heart of a CNTFET. This paper provides an overview of CNTFETs-pH sensor based on carbon nanotubes (CNTs)-FETs-pH measurement range of 1.34 to 12.68, reliability, and low hysteresis, indicating a promising application prospect in harsher testing environments. The determination of carbamate pesticides-adjusting the VTH revealed that carbaryl and carbofuran additions had a favorable effect on the CFO/s-SWCNT-FET and structure. In this chapter, modeling, fabrication, and applications have been discusseddevices.

The accelerating advancement of nanoscience and nanotechnology has established an explosion of potential opportunities for the fabrication of miniaturized nanostructured components with specialized applications in biology, electronics, chemistry, mechanics, and computational functions. This has a huge impact on the special field of biosensors, empowering the fabrication of extremely sensitive, compact, and effective diagnostic equipment. Notably, among these aforementioned advances, the nano-based Field-Effect Transistor (NFET) serves as an attractive candidate for biosensor applications owing to its remarkable attributes, including label-free detection, a high level of sensitivity, rapid response times, continuous measurement capabilities, low consumption of electricity, and potential for miniaturization into compact devices. Each of these traits combines to make nano-based FET biosensors, an interesting and robust technology for a variety of biomedical applications. In recent years, the integration of semiconducting materials, polymers, and carbon-based biocompatible nanomaterials has significantly revolutionized biosensing applications. These materials have been strategically incorporated into various nanostructures to elevate the efficacy and sensitivity of biosensing devices, particularly in the realm of field-effect transistor (FET)- based systems. This proposed book chapter aims to explore the burgeoning landscape of biocompatible nanomaterials and their role in the evolution of biosensing technologies. The utilization of nanomaterials, including metal nanoparticles, polymer nanocomposites, and carbon-based structures, has offered unique opportunities to enhance the performance and reliability of biosensors. Overall, the chapter strives to deliver an inclusive examination of the advancements including potential future directions in the realm of biocompatible nanomaterials, specifically focusing on their integration into FET-based biosensing devices. It aspires to be an essential resource for researchers, scientists, and practitioners in the field of nanotechnology and biosensing

The proposed book chapter aims to present a comprehensive review of nanomaterial-based biosensors utilizing field-effect transistors (FETs), exploring their diverse applications, advancements, and future potentials. The focus will be on examining the integration of carbon-based nanomaterials into FET-based biosensors and their role in revolutionizing biosensing technologies. Field effect-based biosensors (BioFETs) stand out among other biosensing technologies due to their unique features such as real-time screening, ultrasensitive detection, low cost, and amenability to extreme device miniaturization due to the convenient utilization of nanoscale materials. FETbased sensors operate on the principle that changes in the surrounding environment, such as alterations in temperature, pressure, gas concentration, or biological elements, modulate the electrical characteristics of the transistor. The integration of carbon-based nanomaterials into biosensing applications has emerged as a transformative development, significantly augmenting the efficacy and sensitivity of detection devices, particularly within the domain of field-effect transistor (FET) based technologies. The intent is to provide a holistic view of how these advancements have contributed to improving detection capabilities and to outline potential avenues for further research and applications in the field of biosensing.

Over the previous thirty years, the scaling of complementary metal-oxidesemiconductor (CMOS) technology has stood crucial to the continued advancement of the silicon-based semiconductor industry. However, when technological scaling reaches the nanoscale zone, CMOS devices face several significant challenges, including higher leakage currents, difficulty increasing on-current, massive parameter changes, low yield and reliability, increased manufacturing costs, etc. In order to sustain previous advances, numerous developments in CMOS technologies and device topologies have been developed and put into practice. Simultaneously with these investigations, some innovative nanoelectronic devices, labelled as "Beyond CMOS Devices," are currently intensively investigated and developed as potential replacements or supplements for eventually scaled classic CMOS devices. Despite offering system integration at extremely high densities, these nanoelectronic devices continue to be in their infancy and confront numerous challenges, including high variations and low dependability. The actual implementation of these promising technologies necessitates substantial study at the device and system architectural levels.

In this chapter, we address the limitations of device scaling imposed by the subthreshold value restriction of 60mV/decade in the CMOS VLSI design. The focus of current research primarily revolves around effective power methods for cutting-edge electronic devices with additional attributes. Instead of conventional homo-junction MOS devices, our investigation explores the utilization of heterojunctions with SiGe and Ge as these materials have a lower bandgap. By employing a Heterojunction Tunneling Field Effect Transistor (HTFET), we demonstrate a reduction in the subthreshold swing value and achieve low leakage current. We present a revolutionary HTFET design with Gate Oxide Overlap onto Source (GOS) to improve the futuristic features of low-power devices for ultra-low-power memory applications. We implement both n-type and p-type GOS HTFETs, contributing to energy-efficient SRAM cells, by combining low bandgap materials such as SiGe or Ge with high-k dielectrics. The suggested devices show large improvements in Miller capacitance together with a noteworthy decrease in subthreshold swing, high current ratios from ON to OFF, and an increased drive current proportion in the ON state. Expanding the application scope, the proposed device is integrated into a radiation-hardened 14T SRAM cell, showcasing superior performance compared to traditional designs. Memory activities are accelerated, and the chapter concludes with a comparative power and delay analysis of HTFETs-based SRAM cells.

Mercury Cadmium Telluride (Hg1–xCdxTe) stands out as the predominant material for developing infrared (IR) detectors. In this chapter, the two-dimensional (2D) p-n (single homojunction and single heterojunction) and p-i-n (dual-heterojunction) architecture models of p+-Hg0.7783Cd0.2217Te/n–-Hg0.7783Cd0.2217Te, p+- Hg0.69Cd0.31Te/n–-Hg0.7783Cd0.2217Te, and n+-Hg0.68Cd0.32Te/n–- Hg0.7783Cd0.2217Te/p+-Hg0.7783Cd0.2217Te are proposed in long-wavelength infrared (LWIR) spectral region. The detectors are designed and analyzed for various optoelectronic characteristic parameters. The outcomes achieved through the Silvaco Atlas TCAD software are compared with those derived from analytical expressions and are found to agree with the analytical results. The proposed detectors are well-suited for their functioning at a wavelength of 10.6 μm under the condition of liquid nitrogen temperature (77 K). The single homojunction-based detector shows an external quantum efficiency (QEext) of 58.29%, a 3-dB cut-off frequency (f3-dB) of 104 GHz with a response time of 3.3 ps, whereas the heterojunction-based detector exhibits a QEext of 67.6%, a f3-dB of 265 GHz with a response time of 1.3 ps, and least dark current density. On the other hand, a dual-junction-based detector exhibits a QEext of 84.92%, a f3-dB of 1.28 THz with a response time of 0.27 ps, further confirming the suitability of the proposed dual-junction detector for low-noise operations.

The evolution of the Nanostructure Field Effect Transistor (Nano FET) has provided significant progress in healthcare applications. Inherent properties such as easy integration, high sensitivity, and better selectivity increased the role of Nano FET devices in wearable electronic devices. Nano FET biosensors have placed great attention in the biomedical field, which performs label-free biomolecule sensing to screen out various diseases. The detection includes cancer biomarkers, cardiovascular diseases, diabetes, HIV/AIDS, DNA and RNA, and viral and bacterial infections. This chapter discusses the overview of diverse applications in healthcare, challenges, and future technologies of NanoFET devices.