1. Crystal Properties and Growth of Semiconductors

1. Crystal Properties and Growth of Semiconductors

1. Crystal Properties and Growth of Semiconductors Electrical behavior of solids Arrangement of atoms 1.1. Semiconductor Materials Electrical conductivity intermediate between metals and insulators

1 What distinguishes semiconductors? resistance/resistivity crystalline structure The resistance of a bar of material with dimensions L, W, t: W L R Wt

t L Resistivity is: metals: < 10-3-cm insulators: >102-cm semiconductors: 10-3-cm < < 102-cm 2

Figure 1: Electrical conductivities of some common materials. 3 *Conductivity of semiconductor material can be varied over orders of magnitude by changes in -temperature -optical excitation -impurity content Periodic table: Column IV Si, Ge Elemental semiconductors

III-V Compound semiconductors example:GaAs II-VI Compound semiconductors example:CdTe 4 The Portion of Periodic Table Where Semiconductors Occur 5 Binary compounds: GaAs, GaP, GaN, CdTe, InP etc. Ternary compounds: AlGaAs, GaAsP, HgCdTe, etc. Quaternary compounds: InGaAsP, AlGaInAs,etc.

Applications: *transistors, integrated circuits (Si) *light emitting diodes (LEDs) (GaAs,GaN, GaP) *lasers (AlGaInAs, InGaAsP, GaAs, AlGaAs) *light detectors(Si, InGaAsP, CdSe, InSb, HgCdTe) 6 1.2. Crystal Lattices Solids classified according to atomic arrangement: Crystalline Amorphous

Polycrystalline (a) Crystalline Polycrystalline (b) Amorphous (c) 7 The atoms making up the CRYSTAL are arranged in a periodic fashion called

LATTICE. UNIT CELL is a representative of the entire lattice and is generally repeated throughout the structure. PRIMITIVE CELL is the smallest unit cell that can be repeated to form the lattice. Crystal lattice determines: Density of solid (mechanical property) Allowed energy bands of electrons (electrical property). 8 Cubic Lattices

Simple (SC) Body-centered (BCC) Face-centered (FCC) a lattice constant 9 Diamond Lattice

Top view Diamond lattice is an FCC plus placing atoms a, a, a (in x, y and z direction) from each atom in the FCC. Construction of a diamond lattice from two interpenetrating FCC sublattices. 10 Diamond Lattice of Si from Different Angles of View

11 *Diamond (zincblende) lattice - typical of most of the commonly used semiconductors. *Characteristic of Si, Ge, III-V compounds. *Possible to vary the composition of alloy by choosing the fraction of numbers of the atoms, par example: AlxGa1-xAs (x % of Al, (1-x)% of Ga) InxGa1-xAsyP1-y 12

Conclusion Atomic arrangement in certain planes in crystal is important to many of the mechanical, metallurgical, and chemical properties of the material. Crystals cleaved along certain atomic

planes, resulting in exeptionally planar surfaces Chemical reactions-etching of a crytal often take place preferentially along certain directions 13

Recently Viewed Presentations

  • Itec 3220 - people.math.yorku.ca

    Itec 3220 - people.math.yorku.ca

    Times New Roman Arial Franklin Gothic Demi Cond Century Gothic Wingdings a York1 1_a York1 ITEC 2620M Introduction to Data Structures Stacks and Queues Stack-based Recursion Stacks and Recursion Queues Priority Queues Heaps and Heapsort Key Points Heaps Removing the...
  • Főcím - Eötvös Loránd University

    Főcím - Eötvös Loránd University

    A légi közlekedés idő- és költségterének vizsgálati kérdései „Közlekedés - mozgásban a területi kutatások" című konferencia
  • PowerPoint-Präsentation

    PowerPoint-Präsentation

    & Mahoney advised that an analysis of the individual items should be conducted additionally to allow for a pinpoint identification of the deficits. ... Hoogerduijn JG, Schuurmans MJ, Duijnstee MSH, de Rooij SE, Grypdonck MFH (2006) A ...
  • BS Interdisciplinary Engineering EH Presentation, November 16, 2017

    BS Interdisciplinary Engineering EH Presentation, November 16, 2017

    Engineering Creativity (ENGR 260) Enterprise Basics for Technical Entrepreneurs (ENGR 36X) Sales, Operations, and Manufacturing for Technical Companies (ENGR 36Y) Technology Company Management, Leadership, and Corporate Culture (ENGR 46Z) Product Lean Launch (ENGR 461) Engineering Entrepreneurship Hour (ENGR 462)
  • Demand Flow Technology - elsmar.com

    Demand Flow Technology - elsmar.com

    Principles of Lean Manufacturing Objectives Develop the knowledge of what the philosophies and techniques are and why they are important Total picture of the the demand flow technology business strategy Understand and establish how to perform the techniques and skills...
  • Machine Design Analyis - University of Washington

    Machine Design Analyis - University of Washington

    Arial Symbol Default Design Microsoft Equation 3.0 PowerPoint Presentation S-N Diagram Safety Factor Example Facture Mechanics Method of Fatigue Crack Growth Fatigue Life Fatigue Crack Growth Rate Crack Grow Rate Crack Growth Rate Effect of R Ratio Example Example Assignment
  • Bureau of Indian Affairs Southern Plains Regional Office

    Bureau of Indian Affairs Southern Plains Regional Office

    Tribes utilize this funding for salaries and related administrative costs for judges, prosecutors, public defenders, court clerks and other court support staff central to the operation of tribal justice systems;
  • Breeds and Classes of Horses

    Breeds and Classes of Horses

    A hand is equal to four inches. The height of the horse is measured from the top of the withers to the ground. A horse that is 15 hands is 60 inches or 5 feet at the withers. Light Horses...