Preface

Semiconductor materials have a long design and manufacturing chain before their use in all types of electronic products, which also need to incorporate various aspects of circuit logic to adapt to current and future needs. Revolutions in the automotive, media and Internet markets depend on this technological synergy, as do other sectors such as banking and financial markets, telemedicine, e-commerce, industrial automation, smart homes, and agriculture, all of which are expected to benefit from these advances.

New power-generation processes and the development of more energy-efficient devices and equipment directly or indirectly involve new advances in semiconductors. Quality of life has greatly improved with the mass production of more affordable devices for individual communication, which directly depends on the reduction of semiconductor costs. Therefore, more efficient and cheaper semiconductor materials can partially solve the problem of the imbalance between energy generation and consumption by individuals and communities.

Semiconductor materials are the basis of photovoltaic cells for on-site electricity generation. They are also used in water purification processes and hydrogen fuel generation. Thus, the field of semiconductor research is interdisciplinary, including chemistry, physics, engineering, and medicine, offering technological solutions in various fields.

New Advances in Semiconductors offers an updated review of semiconductors, including strategies in the field of circuit logic and experiments on some semiconductor materials. It discusses important aspects of the performance of semiconductors, such as environmental parameters of operation optimization, namely, the influence of operating temperature, light incidence, electric current, magnetic field, and even radioactivity. Many devices are influenced by variations of these experimental parameters, from simple diodes and transistors to complex integrated circuits and solar cells.

This book contains six chapters, divided into two sections. Section 1, "Calculations and Simulations in Semiconductors," includes four chapters that discuss several aspects of the mechanisms of action in systems and devices based on semiconductors. They present proposals to obtain greater energy savings in an operational environment and examine how the interfacial mechanisms between semiconductors and electrolytes can be better understood for the continuous improvement of devices in future projects.

Chapter 1 shows how considerations about individual particles introduce additional difficulties in quasi-macroscopic dielectric function calculations and proposes the exclusion of the single-particle effective field model in this type of calculation based on dielectric relaxation matrices. The author proposes that the use of a polyelectronic wave function, as a sufficient condition for the calculations, has the advantage of allowing considerations about the interactions of the electron-hole pair to be disregarded, greatly facilitating the calculations.

Chapter 2 presents a new analytical model for calculating performance in amplitudemodulated systems, which can be very useful for semiconductor optical amplifiers, considering the lower and upper limits of performance. These calculations can be useful for the development of integrated photonic circuit designs that use amplitudemodulated systems, such as optical amplifiers and interconnects. The model is validated through numerical and experimental simulations, including examples of photonic integrated circuit sizing, and shows how the parameters associated with amplitude modulation can be adjusted for application in semiconductor optical amplifiers.

Chapter 3 discusses how the use of a new circuit design based on Tri-State Buffer connection technology can lead to greater efficiency in electronic circuits. The project shows that there are energy savings if a submodule with two logic routines based on ASIC design and Verilog HDL language is inserted into the logic circuit diagram. Thus, the circuit presents greater energy savings due to the reduction of dynamic and total power. These are relevant mathematical approaches, as they demonstrate how energy savings are verified as a function of dissipation reduction. A performance evaluation is also provided for validation in terms of energy dissipated in connections with Tri-State Buffer technology.

Chapter 4 provides an introduction to charge transport at the interphase junction between solid semiconductors and liquid electrolytes. It demonstrates how the changes occur whether the system is illuminated or not, with basic considerations on the use of semiclassical charge transport equations in the semiconductor used as an electrode. The chapter also presents the behavior of the ideal interface between the semiconductor and the electrolyte at a broad level, describing the interactions as a function of the redox reactions in the electrolyte and the energy relations of charge transfer. The proposed system is also interpreted from the point of view of the kinetics of the electron-hole pair recombination during irradiation. Propositions are also made on how the semiconductor surface can be occupied to explain the behavior of the photocurrent-voltage curves.

Section 2, "Semiconductor Materials," contains two chapters. These chapters discuss two important environmental parameters in semiconductor operation. Chapter 5 describes the dependence of electrical resistivity as a function of temperature for dilute magnetic semiconductors. It also presents a specific case of electrical resistivity reduction for a manganese-doped gallium arsenide p-type semiconductor and examines how the behavior of the curves changes as a function of temperature from 0K to 300K. It is shown that, in addition to the temperature dependence, the electrical resistivity of this type of magnetic material also strongly depends on the concentration of dopants in the structure. Considerations on mechanisms of how electrical resistivity considerably affects state density and energy gap are also made.

Chapter 6 discusses the properties and consequences of the response in electronic components and circuits based on semiconductor materials exposed to neutron radiation. It presents the behavior of several semiconductors based on chemical

elements of Group IV and Groups III and V of the periodic table regarding two types of neutron radiation produced by reactions involving deuterium as well as deuterium and tritium. Reaction rates and classification of neutron-induced byproducts are presented, according to their nature and energy.

Please note that this book can be read in or out of sequential order, as there is no progression of basic knowledge level between chapters or sections. We thank each of the chapter authors for bringing us the most current issues in this field of knowledge. This book is a useful resource for students, researchers, and other interested readers.

## **Alberto Adriano Cavalheiro**

Interdisciplinary Laboratory of Advanced Materials of Navirai (LIMAN), State University of Mato Grosso do Sul (UEMS), Navirai-MS, Brazil

Section 1
