Research into gallium nitride (GaN) has borne fruit and holds further promise for the optoelectronics and electronics industries. Among the fields of active research is exploiting GaN for power electronics, with one example being Schottky barriers as power rectifiers. However, one challenge in implementing GaN-based technologies arises from the device processing and choices involved when fabricating metal/semiconductor contacts. Consequently, a study of metallizations to GaN based on thermodynamics with careful selection of the surface treatment and deposition techniques is of the upmost importance. The first objective of this dissertation was to understand the role of HBr in lessening the contaminants on various semiconductor surfaces. Motivated initially a need to passivate Ge nanostructures, HBr vapor was used to remove the native oxide and passivate a Ge wafer, and x-ray photoelectron spectroscopy (XPS) was used to study the surface. For exposures of at least 20 min above the 48% HBr solution, we found a clear reduction in the amount of oxide present. Interestingly, stability against reoxidation in air was greatly improved using longer exposures to HBr vapor, and XPS reveals that bromine is adsorbed onto these surfaces, suggesting that it is physically blocking H2O and O2 molecules from coming into contact and reoxidizing the Ge surface. Given its success as a surface treatment, aqueous HBr was also tested on GaN. The GaN surfaces, examined by XPS, exhibited no noticeable difference in C and O surface contaminants between HBr and HCl, which is widely used for cleaning GaN surfaces. This finding enhanced our confidence in the efficacy of using HCl for surface preparation. The main objective of this dissertation was to choose a pure transition metal, metal alloy, and compound metallization for GaN based on their thermodynamic stability against metallurgical reactions, high work functions, and conductivity. The only pure transition metal in thermodynamic equilibrium with GaN is rhenium (Re). Prior work on Re/n-GaN has demonstrated diodes with good thermal stability, but the diodes were not as high in quality as the ones produced in this dissertation, due in part to improved crystal growth technology as well as improvements in device processing in this dissertation. Re diodes were fabricated to study the effects of deposition, processing, and annealing on the electrical characteristics of the diodes. As-deposited diodes varied dramatically depending on deposition technique. Electron-beam evaporated Re/Au diodes consistently demonstrated low ideality factors (1.02-1.04) and high barrier heights (0.72-0.82 eV), whereas sputtered Re diodes had high ideality factors (1.26-1.73) and low barrier heights (0.38-0.41 eV), likely due to process-induced defects. However, a remarkable improvement was observed in their electrical characteristics when annealed at 500°C for 5 min in which the barrier height improved to 0.74 eV and the ideality factor to 1.02. Compared to baseline palladium (Pd) diodes fabricated on a similar substrate, the Re diodes were more resilient against annealing conditions that degrade their Pd counterparts. Pd diodes consistently showed degradation after a mild thermal excursion (250°C for 2 h) during dielectric deposition, where the barrier height changed from 0.99 eV to 0.92 eV and ideality factor from 1.02 to 1.13. After annealing at 600°C for 5 min (as a direct comparison to Re diodes) the Pd diodes' barrier height changed from 0.92 eV to 0.86 eV and ideality factor changed from 1.13 to 1.56, whereas the Re diodes remained stable. Stacked layers of Ni and Ga were also pursued as a metal gallide metallization given past success of nickel gallide contacts surviving high temperatures better than pure Ni contacts. However, preliminary current-voltage (I-V) characteristics found that our diodes degraded after annealing at 400°C and 600°C, which may be due to the inhomogeneity in Ga deposition, since Ga deposits with an uneven morphology. With some regions containing more Ga than others, Ni may still react in patches. This inhomogeneity across that diode resulted in low barrier heights and high ideality factors. Therefore, it was deemed beneficial to choose another contact to study. MoCxNy diodes deposited via remote plasma atomic layer deposition (PE-ALD) were also investigated as an attractive compound candidate. Not only is MoNx conductive, refractory, and thermally stable on GaN, it has a high work function and exhibits good adhesion to GaN. Films were examined by XPS, grazing incidence x-ray diffraction (GIXRD), and transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) to determine their composition and structure. TEM reveals an abrupt interface between MoCxNy and n-GaN, and that MoCxNy adopts a cubic phase. Remarkably, XPS also shows a significant amount of carbon within the single cubic phase. It is hypothesized that our single-phase MoC0.3N0.7 film is a cubic NaCl-type structure with a lattice parameter of 0.42 nm that has C and N atoms occupying half of the sites on one sublattice. The incorporation of C in our film, and its occupation in the cubic crystal, could be playing a role in improving the electrical characteristics. The diodes demonstrated high barrier height (0.87 eV) after an anneal at 600°C for 5 min, with an ideality factor of 1.02 by I-V measurements, revealing potential for a thermally stable Schottky diode. The conclusions drawn and experiments developed augment the understanding of device fabrication, metallization, and processing for contacts to n-GaN applications for high-temperature and high-power electronics.

Metal Oxide Semiconductors Up-to-date resource highlighting highlights emerging applications of metal oxide semiconductors in various areas and current challenges and directions in commercialization Metal Oxide Semiconductors provides a current understanding of oxide semiconductors, covering fundamentals, synthesizing methods, and applications in diodes, thin-film transistors, gas sensors, solar cells, and more. The text presents state-of-the-art information along with fundamental prerequisites for understanding and discusses the current challenges in pursuing commercialization and future directions of this field. Despite rapid advancements in the materials science and device physics of oxide semiconductors over the past decade, the understanding of science and technology in this field remains incomplete due to its relatively short research history; this book aims to bridge the gap between the rapidly advancing research progress in this field and the demand for relevant materials and devices by researchers, engineers, and students. Written by three highly qualified authors, Metal Oxide Semiconductors discusses sample topics such as: Fabrication techniques and principles, covering vacuum-based methods, including sputtering, atomic layer deposition and evaporation, and solution-based methods Fundamentals, progresses, and potentials of p–n heterojunction diodes, Schottky diodes, metal-insulator-semiconductor diodes, and self-switching diodes Applications in thin-film transistors, detailing the current progresses and challenges towards commercialization for n-type TFTs, p-type TFTs, and circuits Detailed discussions on the working mechanisms and representative devices of oxide-based gas sensors, pressure sensors, and PH sensors Applications in optoelectronics, both in solar cells and ultraviolet photodetectors, covering their parameters, materials, and performance Memory applications, including resistive random-access memory, transistor-structured memory devices, transistor-structured artificial synapse, and optical memory transistors A comprehensive monograph covering all aspects of oxide semiconductors, Metal Oxide Semiconductors is an essential resource for materials scientists, electronics engineers, semiconductor physicists, and professionals in the semiconductor and sensor industries who wish to understand all modern developments that have been made in the field.

Compound Semiconductors 1995 focuses on emerging applications for GaAs and other compound semiconductors, such as InP, GaN, GaSb, ZnSe, and SiC, in the electronics and optoelectronics industries. The book presents the research and development work in all aspects of compound semiconductors. It reflects the maturity of GaAs as a semiconductor material and the rapidly increasing pool of research information on many other compound semiconductors. Covering the full breadth of the subject, from growth through processing to devices and integrated circuits, this volume provides researchers in materials science, device physics, condensed matter physics, and electrical and electronic engineering with a comprehensive overview of developments in this well-established research area.

Compound Semiconductors 1995 focuses on emerging applications for GaAs and other compound semiconductors, such as InP, GaN, GaSb, ZnSe, and SiC, in the electronics and optoelectronics industries. The book presents the research and development work in all aspects of compound semiconductors. It reflects the maturity of GaAs as a semiconductor material and the rapidly increasing pool of research information on many other compound semiconductors. Covering the full breadth of the subject, from growth through processing to devices and integrated circuits, this volume provides researchers in materials science, device physics, condensed matter physics, and electrical and electronic engineering with a comprehensive overview of developments in this well-established research area.

Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed coverage of hydrogen in silicon, chapters are provided that discuss hydrogen-related phenomena in germanium and the neutralization of defects and dopants in III*b1V semiconductors. Provides the most in-depth coverage of hydrogen in silicon available in a single source**Includes an extensive chapter on the neutralization of defects in III*b1V semiconductors**Combines both experimental and theoretical studies to form a comprehensive reference

Semiconductors are at the heart of modern living. Almost everything we do, be it work, travel, communication, or entertainment, all depend on some feature of semiconductor technology. Comprehensive Semiconductor Science and Technology, Six Volume Set captures the breadth of this important field, and presents it in a single source to the large audience who study, make, and exploit semiconductors. Previous attempts at this achievement have been abbreviated, and have omitted important topics. Written and Edited by a truly international team of experts, this work delivers an objective yet cohesive global review of the semiconductor world. The work is divided into three sections. The first section is concerned with the fundamental physics of semiconductors, showing how the electronic features and the lattice dynamics change drastically when systems vary from bulk to a low-dimensional structure and further to a nanometer size. Throughout this section there is an emphasis on the full understanding of the underlying physics. The second section deals largely with the transformation of the conceptual framework of solid state physics into devices and systems which require the growth of extremely high purity, nearly defect-free bulk and epitaxial materials. The last section is devoted to exploitation of the knowledge described in the previous sections to highlight the spectrum of devices we see all around us. Provides a comprehensive global picture of the semiconductor world Each of the work's three sections presents a complete description of one aspect of the whole Written and Edited by a truly international team of experts