Iii Nitride Ultraviolet Emitters Produced By Molecular Beam Epitaxy

Since the initial breakthroughs in structural quality and p-type conductivity in GaN during the late 1980s, the group-III nitride material system has attracted an enormous amount of interest because of its properties and applications in both electronics and optoelectronics. Although blue light-emitting diodes have been commercialized based on this success, much less progress has been made in ultraviolet emitters, green emitters, and photovoltaics. This lack of development has been attributed to insufficient structural and electrical material quality, which is directly linked to the growth of the material. The objective of this work is to expand the understanding of III-nitride growth towards the improvement of current device capabilities and the facilitation of novel device designs. :Group-III nitride thin films are grown by molecular-beam epitaxy in a pulsed, metal-rich environment. The growths of nitride binaries and ternaries are observed in situ by transient reflection high-energy electron diffraction (RHEED) intensities, which respond to the behavior of atoms on the growing surface. By analyzing and interpreting these RHEED signatures, a comprehensive understanding of nitride thin film growth is obtained. :The growth kinetics of unintentionally doped GaN by metal-rich MBE are elucidated, and a novel method of in situ growth rate measurement is discovered. This technique is expanded to InN, highlighting the similarity in molecular-beam epitaxy growth kinetics between III-nitride binaries. The growth of Mg-doped GaN is then explored to increase Mg incorporation and electrical activation. The growth of InxGa1-xN alloys are investigated with the goal of eliminating phase separation, which enables single-phase material for use in photovoltaics. Finally, the growth of unintentionally doped and Mg-doped AlGaN is investigated towards higher efficiency light emitting diodes. :These advancements in the understanding of III-nitride growth will address several critical problems and enable devices relying on consistent growth in production, single-phase material, and practical hole concentrations in materials with high carrier activation energies.

This book provides a comprehensive overview of the state-of-the-art in group III-nitride based ultraviolet LED and laser technologies, covering different substrate approaches, a review of optical, electronic and structural properties of InAlGaN materials as well as various optoelectronic components. In addition, the book gives an overview of a number of key application areas for UV emitters and detectors, including water purification, phototherapy, sensing, and UV curing. The book is written for researchers and graduate level students in the area of semiconductor materials, optoelectronics and devices as well as developers and engineers in the various application fields of UV emitters and detectors.

Discover a comprehensive exploration of the foundations and frontiers of the optoelectronics technology of group-III nitrides and their ternary alloys In Group III-Nitride Semiconductor Optoelectronics, expert engineer Dr. Choudhury J. Praharaj delivers an insightful overview of the optoelectronic applications of group III-nitride semiconductors. The book covers all relevant aspects of optical emission and detection, including the challenges of optoelectronic integration and a detailed comparison with other material systems. The author discusses band structure and optical properties of III-nitride semiconductors, as well as the properties of their low-dimensional structures. He also describes different optoelectronic systems such as LEDs, lasers, photodetectors, and optoelectronic integrated circuits. Group III-Nitride Semiconductor Optoelectronics covers both the fundamentals of the field and the most cutting-edge discoveries. Detailed appendices contain Maxwell's equations in dielectric media and descriptions of time-dependent perturbation theory and light-matter interaction. Readers will also benefit from: A thorough introduction to the band structure and optical properties of group III-nitride semiconductors Comprehensive explorations of growth and doping of group III-nitride devices and heterostructures Practical discussions of the optical properties of low dimensional structures in group III-nitrides In-depth examinations of lasers and light-emitting diodes, other light-emitting devices, photodetectors, photovoltaics, and optoelectronic integrated circuits Concise treatments of the quantum optical properties of nitride semiconductor devices Perfect for researchers in electrical engineering, applied physics, and materials science, Group III-Nitride Semiconductor Optoelectronics is also a must-read resource for graduate students and industry practitioners in those fields seeking a state-of-the-art reference on the optoelectronics technology of group III-nitrides.

Molecular Beam Epitaxy (MBE): From Research to Mass Production, Second Edition, provides a comprehensive overview of the latest MBE research and applications in epitaxial growth, along with a detailed discussion and ‘how to’ on processing molecular or atomic beams that occur on the surface of a heated crystalline substrate in a vacuum. The techniques addressed in the book can be deployed wherever precise thin-film devices with enhanced and unique properties for computing, optics or photonics are required. It includes new semiconductor materials, new device structures that are commercially available, and many that are at the advanced research stage. This second edition covers the advances made by MBE, both in research and in the mass production of electronic and optoelectronic devices. Enhancements include new chapters on MBE growth of 2D materials, Si-Ge materials, AIN and GaN materials, and hybrid ferromagnet and semiconductor structures. Condenses the fundamental science of MBE into a modern reference, speeding up literature review Discusses new materials, novel applications and new device structures, grounding current commercial applications with modern understanding in industry and research Includes coverage of MBE as mass production epitaxial technology and how it enhances processing efficiency and throughput for the semiconductor industry and nanostructured semiconductor materials research community

III-Nitride semiconductor materials OCo (Al, In, Ga)N OCo are excellent wide band gap semiconductors very suitable for modern electronic and optoelectronic applications. Remarkable breakthroughs have been achieved recently, and current knowledge and data published have to be modified and upgraded. This book presents the new developments and achievements in the field. Written by renowned experts, the review chapters in this book cover the most important topics and achievements in recent years, discuss progress made by different groups, and suggest future directions. Each chapter also describes the basis of theory or experiment. The III-Nitride-based industry is building up and new economic developments from these materials are promising. It is expected that III-Nitride-based LEDs may replace traditional light bulbs to realize a revolution in lighting. This book is a valuable source of information for engineers, scientists and students working towards such goals. Sample Chapter(s). Chapter 1: Hydride Vapor Phase Epitaxy of Group III Nitride Materials (540 KB). Contents: Hydride Vapor Phase Epitaxy of Group III Nitride Materials (V Dmitriev & A Usikov); Planar MOVPE Technology for Epitaxy of III-Nitride Materials (M Dauelsberg et al.); Close-Coupled Showerhead MOCVD Technology for the Epitaxy of GaN and Related Materials (E J Thrush & A R Boyd); Molecular Beam Epitaxy for III-N Materials (H Tang & J Webb); Growth and Properties of Nonpolar GaN Films and Heterostructures (Y J Sun & O Brandt); Indium-Nitride Growth by High-Pressure CVD: Real-Time and Ex-Situ Characterization (N Dietz); A New Look on InN (L-W Tu et al.); Growth and Optical/Electrical Properties of Al x Ga 1-x N Alloys in the Full Composition Range (F Yun); Optical Investigation of InGaN/GaN Quantum Well Structures Grown by MOCVD (T Wang); Clustering Nanostructures and Optical Characteristics in InGaN/GaN Quantum-Well Structures with Silicon Doping (Y-C Cheng et al.); III-Nitrides Micro- and Nano-Structures (H M Ng & A Chowdhury); New Developments in Dilute Nitride Semiconductor Research (W Shan et al.). Readership: Scientists; material growers and evaluators; device design, processing engineers; postgraduate and graduate students in electrical & electronic engineering and materials engineering.

Significant progress has been achieved in the past two decades in III-nitride light emitters. It has captured the attention of the scientific community due to applications in solid-state lighting, sterilization, gas sensing, and polymer curing. The success in p-type GaN revolutionized the lighting industry. However, hole injection still remains as a bottleneck in the nitride semiconductor LEDs and LDs. The low hole density poses significantly more challenges for emission wavelength in the deeper ultraviolet regime. Recently, tunnel junction based GaN LEDs were explored to reduce the contact resistance to p-type layer and enhance the current spreading. The first topic is the theoretical design and experimental demonstration of tunnel junctions using polarization engineering. A theoretically predicted design is put to test using blue LED heterostructures grown by molecular beam epitaxy. The results show that polarization engineering enhances hole injection by tunneling, and identifies the operation regime in which is the enhancement can be leveraged. To enable efficient electrically injected deep-UV photonic devices, a detailed study of Mg doping in AlGaInN is performed. A significant enhancement of Mg incorporation efficiency is observed for InGaN and AlGaN alloys compared to GaN. Optimal Mg doping concentration in InGaN results in a very high hole concentration of 1019 cm-3 at room temperature, significantly higher than what is achieved in p-type GaN. Incorporating such p-InGaN layer in the p-type contacts of UV-C LEDs significantly reduces the p-contact resistance, enabling continuous wave operation compared to pulsed operation p-GaN contact device at 243nm. Similar Mg doping optimization in graded p-AlGaN layers also exhibit ~1000 times improvement over constant p-AlGaN to a resistivity of 104 Ω_cm. Homoepitaxy of AlN on newly available bulk AlN crystals by MBE is a critical enabler for quantum heterostructures for electronic and photonic devices. To enable homoepitaxy of AlN, a new surface preparation technique using plasma-assisted molecular beam epitaxy is presented. A growth window to achieve smooth parallel atomic steps on single crystal bulk AlN substrate is identified. High Al-content AlGaN layers are then grown pseudomorphically on the bulk AlN without relaxation. AlGaN and AlN epitaxial layers with very low impurity concentrations such as Si, O, H, and C are measured by secondary ion mass spectrometry. These findings are the critical enablers of MBE-grown UV lasers and high performance power electronic devices on low dislocation density bulk AlN substrates.