Introduction to Nano

Over the last 15–20 years there has been a lot of buzz surrounding the word “nanotechnology” [1‐7]. A lot is being printed in the press and being aired in the media regarding how this new technology is changing the world around us with myriad applications. It is already touching the everyday lives of people in various avatars such as nanoparticles containing sunscreen lotions, dirt-resistant glass/paint with nanocoatings, the lab on a chip (also known as the micro testing and analyzing system; µ-TAS in short), and the various nanocomposite materials. This chapter looks to introduce the readers to what nanotechnology is about.

We live in a macroscopic world surrounded by macroscopic objects, which adhere to the laws of classical mechanics and are very comfortable with it. From the trajectory of a humble pebble thrown into a pond and the ripples thus created by it, to the motion of the great planets can all be quite satisfactorily explained within the domain of classical physics. However, apart from this macroscopic scale, there exist numerous other phenomena around us, especially on the microscopic scale, which seem to defy most conventional “common-sense” beliefs. The key to the understanding of the workings of this amazing microscopic world lies with quantum physics.

The physics and structure of solid materials is an extremely vast and interesting field of study. In this chapter, we would only look at the basic concepts of solid-state physics, with an outlook toward nanocrystalline solids.

Modern-day electronic devices need to provide high current densities for VLSI applications that eventually force shrinking device dimensions. At an era of nanoelectronic device research, more and more devices are being fabricated where device lengths are downscaled far below the 100 nm range. At that limit, quantum mechanical effects become a dominating factor and a better understanding of such devices can only be achieved by applying necessary quantum corrections. In this chapter, we shall focus on the basics of quantum mechanics which will be useful for lower dimensional devices like quantum wire or quantum dot.

The physical properties of the material significantly depend on their size when reduced to nanodimension. In bulk system, most of the atoms are the interior atoms, so the properties of the materials are determined by them. But in the case of nanoparticles, the fraction of surface atoms cannot be neglected. To illustrate the increasing contribution of surface atoms, let us consider the following example of spherical nanoparticle having radius “r.” Thus surface-(S)-to-volume (V) ratio (S/V) = 3/r for such nanoparticle dramatically increases as its size is reduced Since surface atoms have different environment in contrast to interior atoms, their behaviors to any external excitation are completely different. The size effect becomes prominent when their size is ~5–50 nm.

During past few decades, nanoparticles have attracted large number research scientist due to their exotic properties originating from their smaller size (less than 100 nm). Various methods and growth mechanism have been proposed to for nanoparticles having different morphologies like cubes, polyhedrons, rods, rings etc. Due to larger surface area and quantum effect, nanoparticles often possesses properties completely different from bulk those make it possible to use them in the field of single electron devices, nanoelectronics, drug delivery etc. They can be used to generate various predetermined structure in order to achieve some specific purpose. In this chapter, we’ll first introduce few methods to synthesis nanoparticles and then some characterization techniques will be discussed in order to understand their physical properties.

Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) has emerged over the last few decades as the basic building block of almost all computing devices. This steady growth of MOS transistors is attributed to the scaling of the underlying MOS technology which at present has reached the nanoscale (sub-90 nm) regime. Although the industry roadmap has suggested that the MOS transistor in its classical form is rapidly approaching toward some fundamental physical limits, yet many semiconductor industries prefer to use classical MOS transistor device structure because of the simplicity of operation and success of the use of such transistors in low cost-integrated circuits and systems.

With the conventional MOS Non-Volatile Memory (NVM) devices nearing its limits due to scaling issues; many new devices, advanced structures and materials are being explored for their memory applications. The advanced MOSFET NVMs like the nanocrystal embedded gate dielectric Double Gate (DG) MOS, FinFET and Gate all around (GAA) MOSFET are expected to be integrated in the 3-Dimensional ICs by 2015. Also another class of NVMs which operate based on rather different phenomena than charge trapping (as in MOS devices) has come to the fore in recent years. This new generation of NVMs include the Resistive RAM (RRAM), Ferro FET (FeFET), Spin Torque Transfer (STT)-RAM, CNT/Graphene based memories, CNT mass transport and NEMS NVM etc. Such devices depend on processes like resistive switching, ferroelectric hysteresis, spin-torque transfer and tunneling magnetoresistance modulation, nano manipulation, cantilever actuation and so on. These new NVMs offer considerably faster switching, low power and denser and longer data storage capabilities than the present MOS NVMs. Also the advances in nanofabrication techniques have brought about possibilities of realizing complex multi-layer and 3-D structures with great accuracy. All these developments in materials and design are all set to revolutionize the memory technology. The underlying physics and the quantum effects in such next generation NVM devices are a truly intriguing field of study as well. Various models have been proposed and many new ones are being put forward to study the electron tunneling currents nanocrystal embedded gate advanced MOSFET NVMs, the filament formation mechanisms in RRAM, the spin torque transfer in MRRAM and the various other physical phenomena in such devices. This Chapter provides a comprehensive and up-to date review on the recent developments in the field of NVM devices, discussing new memory devices, architectures and novel data storage mechanisms, with in depth discussions regarding the physics based modeling of such memory cells.

The term sensor comes from the Latin word ‘sentire’ which means to perceive (Sze in Semiconductor sensors. Wiley, New York, 1994 [1]). In electronics sensors are a type of devices that converts some non-electrical input parameter (which we want to measure) into electrical signals having some correlation with the magnitude and nature of the input. Sensors have invaded every sphere of modern industry. In industrial automation, consumer electronics, automobile, space-exploration, medical sector, sensors are everywhere. One of the chief applications of sensors is for the detection of gases and chemical vapors.