Semiconductors
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Iii-Nitride Ultraviolet Light-Emitting Diodes: Approaches for the Enhanced Efficiency
Copyright Warning & Restrictions The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted material. Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be “used for any purpose other than private study, scholarship, or research.” If a, user makes a request for, or later uses, a photocopy or reproduction for purposes in excess of “fair use” that user may be liable for copyright infringement, This institution reserves the right to refuse to accept a copying order if, in its judgment, fulfillment of the order would involve violation of copyright law. Please Note: The author retains the copyright while the New Jersey Institute of Technology reserves the right to distribute this thesis or dissertation Printing note: If you do not wish to print this page, then select “Pages from: first page # to: last page #” on the print dialog screen The Van Houten library has removed some of the personal information and all signatures from the approval page and biographical sketches of theses and dissertations in order to protect the identity of NJIT graduates and faculty. ABSTRACT III-NITRIDE ULTRAVIOLET LIGHT-EMITTING DIODES: APPROACHES FOR THE ENHANCED EFFICIENCY by Moulik Patel III-nitride ultraviolet (UV) light-emitting diodes (LEDs) offer marvelous potential for a wide range of applications, including air/water purification, surface disinfection, biochemical sensing, cancer cell elimination, and many more. III-nitride semiconductor alloys, especially AlGaN and AlInN, have drawn significant attention due to their significant advantages that include environmental-friendly material composition, compact in size, longer lifetime, low power consumption, and tunable optical emission. -
Sudan University of Science and Technology College of Graduate Studies
Sudan University of Science and Technology College of Graduate Studies Increasing The Electrical Conductivity of the semiconductor by Doping and Heating زﯾﺎدة اﻟﻤﻮﺻﻠﯿﺔ اﻟﻜﮭﺮﺑﯿﺔ ﻻﺷﺒﺎه اﻟﻤﻮﺻﻼت ﺑﺎﻟﺘﺸﻮﯾﺐ و اﻟﺤﺮارة Thesis Submitted For Partial Fulfillment of the Requirement for Degree of Master in Physics Prepared by : Seddega Mohammed Noor Diab Supervised by : Dr. Ahmed ELhassan ELfaki December 2016 1 اﻵﯾــــــــــــــــــﺔ ﻗﺎل ﺗﻌﺎﻟﻰ: ﺑﺳم اﻟﻠﮫ اﻟرﺣﻣن اﻟرﺣﯾم ﯾُﻜَﻠّ ِﻒُ اﻟﻠﱠﮫُ (ﻧَﻔْﺴًﺎ ﻻ َإِﻻ ﱠ وُﺳْﻌَﮭَﺎ ﻟَﮭَﺎ ﻣَﺎ ﻛَﺴَﺒَﺖْ و َﻋَﻠَﯿْﮭَﺎ ﻣَﺎ اﻛْﺘَﺴَﺒَﺖْ رَﺑﱠﻨَﺎ ﻻ َ ﻧﱠﺴِﯿﻨَﺎ أَوْ ﺗُﺆَاﺧِﺬْﻧَﺎ أَﺧْﻄَﺄ إِن ْﻧَﺎ رَﺑﱠﻨَﺎ و َﻻ َ ﺗَﺤْﻤِﻞْ ﻋَﻠَﯿْﻨَﺎ إِﺻْﺮًا ﻛَﻤَﺎ ﺣَﻤَﻠْﺘَﮫُ ﻋَﻠَﻰ َ ﻣِﻦ ﻗَﺒْﻠِﻨَﺎ رَﺑﱠﻨَﺎاﻟ و ﱠﺬِﯾﻦَﻻ َ ﺗُﺤَﻤِّﻠْﻨَﺎ ﻣَﺎ ﻻ َ طَﺎﻗَﺔَ ﻟَﻨَﺎ ﺑِﮫِ و َاﻋْﻒُ ﻋَﻨﱠﺎ و َاﻏْﻔِﺮْ ﻟَﻨَﺎ و َارْﺣَﻤْﻨَﺎ أَﻧﺖَ ﻣَﻮْﻻ َ ﻧَﺎ ﻓَﺎﻧﺼُﺮْﻧَﺎ ﻋَﻠَﻰ ﻘَﻮْمِاﻟْ اﻟْﻜَﺎﻓِﺮ ِﯾﻦَ ) ﺻدق اﻟﻠﮫ اﻟﻌظﯾم ﺳورة اﻟﺑﻘرة اﻷﯾﺔ (286) Dedication To whom he strives to bless comfort and welfare and never stints what he owns to push me in the success way who I taught me to promote life stairs wisely and patiently, to my dearest father To the Spring that never stops giving, to my mother who weaves my happiness with strings from her merciful heart To whose love flows in my veins, and my heart always remembers them, to my brothers ,sisters and my fiends To those who taught us letters of gold and words of jewel of the utmost and sweetest sentences in the whole knowledge. Who reworded to us their knowledge simply and from their thoughts made a lighthouse guides us through the knowledge and success path, To our honored teachers and professors. -
CHAPTER 8: Diffusion
1 Chapter 8 CHAPTER 8: Diffusion Diffusion and ion implantation are the two key processes to introduce a controlled amount of dopants into semiconductors and to alter the conductivity type. Figure 8.1 compares these two techniques and the resulting dopant profiles. In the diffusion process, the dopant atoms are introduced from the gas phase of by using doped-oxide sources. The doping concentration decreases monotonically from the surface, and the in-depth distribution of the dopant is determined mainly by the temperature and diffusion time. Figure 8.1b reveals the ion implantation process, which will be discussed in Chapter 9. Generally speaking, diffusion and ion implantation complement each other. For instance, diffusion is used to form a deep junction, such as an n-tub in a CMOS device, while ion implantation is utilized to form a shallow junction, like a source / drain junction of a MOSFET. Boron is the most common p-type impurity in silicon, whereas arsenic and phosphorus are used extensively as n-type dopants. These three elements are highly soluble in silicon with solubilities exceeding 5 x 1020 atoms / cm3 in the diffusion temperature range (between 800oC and 1200oC). These dopants can be introduced via several means, including solid sources (BN for B, As2O3 for As, and P2O5 for P), liquid sources (BBr3, AsCl3, and POCl3), and gaseous sources (B2H6, AsH3, and PH3). Usually, the gaseous source is transported to the semiconductor surface by an inert gas (e.g. N2) and is then reduced at the surface. 2 Chapter 8 Figure 8.1: Comparison of (a) diffusion and (b) ion implantation for the selective introduction of dopants into a semiconductor substrate. -
Which Pnictogen Is Best?† Cite This: New J
NJC PAPER Pnictogen bonding with alkoxide cages: which pnictogen is best?† Cite this: New J. Chem., 2019, 43,14305 Henry J. Trubenstein, ‡ Shiva Moaven, ‡ Maythe Vega, Daniel K. Unruh and Anthony F. Cozzolino * Pnictogen bonding is beginning to emerge as a useful supramolecular interaction. The design strategies for these systems are still in the early stages of development and much attention has been focused on the lighter pnictogens. Pnictogen bond donors can have up to three independent sites for binding which can result in triple pnictogen bonding. This has been observed in the self-assembly of antimony alkoxide cages, but not with the lighter congeners. This work reports structural characterization of an analogous arsenic alkoxide cage that engages in a single pnictogen bond and synthetic explorations of Received 14th July 2019, the bismuth congener. DFT calculations are used to evaluate the differences between the structures. Accepted 13th August 2019 Ultimately the partial charge on the pnictogen and the energy of the pnictogen lone pair dictate the DOI: 10.1039/c9nj03648b strength, orientation and number of pnictogen bonds that these cages form. Antimony cages strike the best balance between strength and directionality, allowing them to achieve triple pnictogen bonding rsc.li/njc where the other congeners do not. Introduction or bismuth.15–23 Recently, antimony centred PnBs have been purposefully designed into molecules to actively direct the self- A pnictogen bond (PnB), in analogy to a halogen or chalcogen assembly of reversed bilayer vesicles,24 enable anion binding bond (XB/HaB or ChB), is ‘‘the net attractive interaction between with applications in sensing and transport,25–28 self-assembly an electrophilic region associated with a [pnictogen] atom in a complex architectures through triple pnictogen bonding29 and molecular entity [the PnB donor] and a nucleophilic region in allow for supramolecular catalysis.30 These applications rely on another, or the same, molecular entity [the PnB acceptor].’’1 the predictable formation of PnBs. -
Introduction to Semiconductor
Introduction to semiconductor Semiconductors: A semiconductor material is one whose electrical properties lie in between those of insulators and good conductors. Examples are: germanium and silicon. In terms of energy bands, semiconductors can be defined as those materials which have almost an empty conduction band and almost filled valence band with a very narrow energy gap (of the order of 1 eV) separating the two. Types of Semiconductors: Semiconductor may be classified as under: a. Intrinsic Semiconductors An intrinsic semiconductor is one which is made of the semiconductor material in its extremely pure form. Examples of such semiconductors are: pure germanium and silicon which have forbidden energy gaps of 0.72 eV and 1.1 eV respectively. The energy gap is so small that even at ordinary room temperature; there are many electrons which possess sufficient energy to jump across the small energy gap between the valence and the conduction bands. 1 Alternatively, an intrinsic semiconductor may be defined as one in which the number of conduction electrons is equal to the number of holes. Schematic energy band diagram of an intrinsic semiconductor at room temperature is shown in Fig. below. b. Extrinsic Semiconductors: Those intrinsic semiconductors to which some suitable impurity or doping agent or doping has been added in extremely small amounts (about 1 part in 108) are called extrinsic or impurity semiconductors. Depending on the type of doping material used, extrinsic semiconductors can be sub-divided into two classes: (i) N-type semiconductors and (ii) P-type semiconductors. 2 (i) N-type Extrinsic Semiconductor: This type of semiconductor is obtained when a pentavalent material like antimonty (Sb) is added to pure germanium crystal. -
Donor Qubits in Silicon
04/09/2015 Experiments with spin qubits in siliconDonor and diamond qubits in silicon Gavin W Morley University of Warwick Gavin W Morley, Spin qubits in silicon and diamond, QuICC Warwick, August 2015 Experiments with spin qubits in silicon and diamond: overview • Lecture 1 – Magnetic resonance – Silicon • Lecture 2 – Silicon (cont.) Lab tours • Lecture 3 Friday morning – Diamond Gavin W Morley, Spin qubits in silicon and diamond, QuICC Warwick, August 2015 1 04/09/2015 Experiments with spin qubits in silicon and diamond: overview • Lecture 1 – Magnetic resonance 1. Prepare (spin Hamiltonian) 2. Control (electromagnetic pulses) 3. Measure (spin state readout) – Silicon Gavin W Morley, Spin qubits in silicon and diamond, QuICC Warwick, August 2015 – Magnetic resonance 1. Prepare (spin Hamiltonian) 2. Control (electromagnetic pulses) 3. Measure (spin state readout) Gavin W Morley, Spin qubits in silicon and diamond, QuICC Warwick, August 2015 2 04/09/2015 Magnetic resonance: prepare - put a spin ½ into a magnetic field H Ŝ Hamiltonian = ωS z with energy, ħ ωS = g µB B0 for g-factor, g ~ 2, Bohr magneton µB = e ħ/2me, electron spin S = ½ Energy m = ½ of a s spin Magnetic field, B0 ms = -½ Gavin W Morley, Spin qubits in silicon and diamond, QuICC Warwick, August 2015 Magnetic resonance: prepare - put a spin ½ into a magnetic field Larmor precession at angular frequency ωS Gavin W Morley, Spin qubits in silicon and diamond, QuICC Warwick, August 2015 3 04/09/2015 Magnetic resonance: prepare - put a spin ½ into a magnetic field Larmor precession -
Donor-Acceptor Methods for Band Gap Reduction in Conjugated Polymers: the Role of Electron Rich Donor Heterocycles
DONOR-ACCEPTOR METHODS FOR BAND GAP REDUCTION IN CONJUGATED POLYMERS: THE ROLE OF ELECTRON RICH DONOR HETEROCYCLES By CHRISTOPHER A. THOMAS A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2002 Copyright 2002 by Christopher A. Thomas All rights reserved. ACKNOWLEDGMENTS I thank my parents, Nancy and Larry, for their continuous support and attempts to understand and encourage me during what has been simultaneously the most enjoyable and most stressful part of my life. They made this document possible by encouraging and par- ticipating in experiences that ensured I would have the backgound and interest in trying to figure out how the world works. The decision about whom to work for in graduate school is one of the events I have agonized the most about in my life. As promised, the graduate advisor-student relationship is a complicated entity consisting of advisor, boss, counselor and friend that can change its active role without warning. Despite this, I am positive that there is no other person that I would rather have worked with during this process. I especially appreciate being given an unusual amount of decision making and direction setting power in the projects I was involved with and the freedom to explore aspects of science that interested me even when they did not overlap cleanly with Professor Reynolds’ research interests or funding. For their major contributions to my enjoyment and interest in chemistry, I thank Joe Carolan for his contagious enthusiasm, and Joel Galanda, who immensely affected the three years of my life he was involved with my chemistry and physical science education. -
XI. Band Theory and Semiconductors I
XI. ELECTRONIC PROPERTIES (DRAFT) 11.1 THE ALLOWED ENERGIES OF ELECTRONS Over the next few weeks we are going to explore the electrical properties of materials. Our starting point for this investigation is simply to ask the question, “Why do some materials conduct electricity and others don’t?” It should come as no surprise that the answer to this question can be found in structure, in this case the structure of the electrons density, which in turn is related to the electron energies and how these may change when a material is subjected to an electrical potential difference, i.e., hooked up to a battery. Up until the early part of the twentieth century it was thought that electrons obeyed the laws of classical mechanics, and, just like everything we could observe at that time, an electron could be made to move in a way that it would take on any energy we wished. For example, if we want a ball with the mass of 0.25 kg to have a kinetic energy of 0.5 J, all we need do is accelerate it to exactly 2 m/sec. If we want its kinetic energy to be 0.501 J, then we need to accelerate it to 2.001999 m/sec. If we want it to have a kinetic energy of X, it must have a velocity of exactly (8X)1/2. According to the principles of classical mechanics, there is nothing that prevents us from doing this. However, it turns out that these principles are not quite right, under some circumstances the ball cannot be made to take on any energy we desire, it can only possess specific energies, which we often denote with a subscript, En. -
Donor-Acceptor Properties of Trivalent Phosphorus and Arsenic Ligands Larry James Vande Griend Iowa State University
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1975 Donor-acceptor properties of trivalent phosphorus and arsenic ligands Larry James Vande Griend Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Inorganic Chemistry Commons Recommended Citation Vande Griend, Larry James, "Donor-acceptor properties of trivalent phosphorus and arsenic ligands " (1975). Retrospective Theses and Dissertations. 5764. https://lib.dr.iastate.edu/rtd/5764 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technologcal means to photogaph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. The sign or "terget" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necasitstsd cutung thru an image and du^icating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. -
CHAPTER 1: Semiconductor Materials & Physics
Chapter 1 1 CHAPTER 1: Semiconductor Materials & Physics In this chapter, the basic properties of semiconductors and microelectronic devices are discussed. 1.1 Semiconductor Materials Solid-state materials can be categorized into three classes - insulators, semiconductors, and conductors. As shown in Figure 1.1, the resistivity of semiconductors, ρ, is typically between 10-2 and 108 Ω-cm. The portion of the periodic table related to semiconductors is depicted in Table 1.1. Figure 1.1: Typical range of conductivities for insulators, semiconductors, and conductors. Semiconductors can be composed of a single element such as silicon and germanium or consist of two or more elements for compound semiconductors. A binary III-V semiconductor is one comprising one element from Column III (such as gallium) and another element from Column V (for instance, arsenic). The common element and compound semiconductors are displayed in Table 1.2. City University of Hong Kong Chapter 1 2 Table 1.1: Portion of the Periodic Table Related to Semiconductors. Period Column II III IV V VI 2 B C N Boron Carbon Nitrogen 3 Mg Al Si P S Magnesium Aluminum Silicon Phosphorus Sulfur 4 Zn Ga Ge As Se Zinc Gallium Germanium Arsenic Selenium 5 Cd In Sn Sb Te Cadmium Indium Tin Antimony Tellurium 6 Hg Pd Mercury Lead Table 1.2: Element and compound semiconductors. Elements IV-IV III-V II-VI IV-VI Compounds Compounds Compounds Compounds Si SiC AlAs CdS PbS Ge AlSb CdSe PbTe BN CdTe GaAs ZnS GaP ZnSe GaSb ZnTe InAs InP InSb City University of Hong Kong Chapter 1 3 1.2 Crystal Structure Most semiconductor materials are single crystals. -
Electrical Properties View of an Integrated Circuit Electrical Conduction Electrical Properties
4/28/15 Electrical Properties View of an Integrated Circuit • Scanning electron micrographs of an IC: ISSUES TO ADDRESS... Al (d) • How are electrical conductance and resistance Si characterized? (What effects conductance?) (doped) 45 µm 0.5 mm • What are the physical phenomena that distinguish conductors, semiconductors, and insulators? • A dot map showing location of Si (a semiconductor): • For metals, how is conductivity affected by -- Si shows up as light regions. (b) imperfections, temperature, and deformation? & dark region is Al wiring • For semiconductors, how is conductivity affected by impurities (doping) and temperature? 2 Chapter 18 - 1 Chapter 18 - Electrical Conduction Electrical Properties • Ohm's Law: V = I R • Which will have the greater resistance? voltage drop (volts = J/C) resistance (Ohms) current (amps = C/s) C = Coulomb 2 2ρ 8ρ R D 1 = 2 = 2 !D$ πD • Resistivity, ρ: π # & " 2 % - a material property that is independent of sample size and geometry current flow € ρ ρ R 2D R = = = 1 path length 2 2 2 !2D$ πD 8 cross-sectional area π # & " 2 % of current flow € RA ρ = • Analogous to flow of cars on road • Resistance depends on sample geometry and • Conductivity, σ 1 size. σ = ρ • Resistivity of independent of sample geometry Chapter 18 - 3 Chapter 18 - 4 1 4/28/15 Conductivity: Comparison Definitions Room temperature values in (Ω - m)-1 Further definitions METALS conductors CERAMICS J = σ ε ß another way to state Ohm’s law Silver 6.8 x 10 7 Soda-lime glass 10 -10-10 -11 7 -9 current I Copper 6.0 x 10 Concrete 10 J = current density = = like a flux 7 surface area A Iron 1.0 x 10 Aluminum oxide <10-13 ε = electric field potential = V/ℓ € SEMICONDUCTORS POLYMERS J = σ (V/ℓ ) -14 Silicon 4 x 10 -4 Polystyrene <10 0 -15 -17 Electron flux conductivity voltage gradient Germanium 2 x 10 Polyethylene 10 -10 GaAs 10 -6 semiconductors insulators 6 Chapter 18 - 5 Selected values from Tables 18.1, 18.3, and 18.4, Callister & Rethwisch 9e. -
Bipolar Junction Transistor As a Switch
IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 13, Issue 1 Ver. I (Jan. – Feb. 2018), PP 52-57 www.iosrjournals.org Bipolar Junction Transistor as a Switch Ali Habeb Aseeri1, Fouzeyah Rajab Ali2 1(Switching Dep, High institute of telecommunication and navigation/PAAET, Kuwait,[email protected]) 2(Switching Dep, High institute of telecommunication and navigation/PAAET, Kuwait,[email protected]) Abstract: Understanding the application of a bipolar Junction transistor or BJT as a switch requiers understanding the general working principles behind a transistor and the specific working principles behind a BJT. A transistor is essentially a semiconductor device with physical properties that make it ideal for amplifying or switching electric current and other signal. At the heart of this device is a doped semiconductor with engineered properties to alter its conductivity for a particular use. A BJT is a type of transistor with two major semiconductor materials that constitute three major areas or regions, each doped according to requirements. This architectural characteristics of a BJT brings forth effective applications in implications or on-off switching operations. Nonetheless, understanding BJT as a switch requires understanding the working principles underneath the device, the functions of each of the three major regions within this transistor, and the role of electron movement or current flow in the switching mechanism Keywords: BJT-collector-emitter-base-collector voltage