lecture 2 the crystal structure of solids n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Lecture 2 The Crystal Structure of Solids PowerPoint Presentation
Download Presentation
Lecture 2 The Crystal Structure of Solids

Loading in 2 Seconds...

play fullscreen
1 / 45

Lecture 2 The Crystal Structure of Solids

13 Views Download Presentation
Download Presentation

Lecture 2 The Crystal Structure of Solids

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. DMT 234 SEMICONDUCTOR PHYSICS & DEVICE Lecture 2The Crystal Structure of Solids Nor Roshidah 2012

  2. SUBTOPIC Point defect Line defect CZ FZ Crystal Growth Si, Ge Elementary Frenkel defect Imperfection Impurities S/c material GaAs, GaN InGaN, AlGaAs Compound CRYSTAL STRUCTURE OF SOLIDS Crystal Structure Types amorphous Bonding ionic polycrystalline covalent Single crystalline metallic Van de Walls Structure Direction Crystal plane simple BCC FCC

  3. DMT 234 Semiconductor Physics & Device

  4. DMT 234 Semiconductor Physic & Device

  5. SOLID STATE MATERIAL Solid state material can be grouped into 3 classes

  6. SEMICONDUCTOR MATERIAL

  7. DIFFERENT TYPES OF SOLIDS • i. Amorphous • little or no order • ii. Polycrystalline • High degree of order within limited regions which vary in size and orientation to each other. • iii. Single Crystal • High degree of order throughout the entire volume • of the material.

  8. CRYSTAL STRUCTURE SPACE LATTICES • The regular geometric periodicity in the atomic arrangement. • Lattice –periodic arrangement of atoms in crystal. • Lattice point – a particular atomic array shown by a dot. These dots are separated (translated) in certain directions and dimensions • Unit Cell – a small volume of the crystal that can be used to reproduce the entire crystal.

  9. CRYSTAL STRUCTURE PRIMITIVE CELL AND LATTICE VECTOR • Primitive cell – the smallest unit cell that can be repeated to form the lattice. • Lattice vector – every equivalent lattice point in the three-dimensional crystal can be found by using the vector : • Where p, q and s are integers.

  10. CRYSTAL STRUCTURE BASIC CRYSTAL STRUCTURES

  11. CRYSTAL STRUCTURE SIMPLE CUBIC Number of atom per unit cell (A) : 1/8 x 8 = 1 Volume of unit cell (B) : a3 Volume density of atom = A/B = 1/ a3

  12. CRYSTAL STRUCTURE FACE-CENTERED CUBIC Number of atom per unit cell (A) : (1/8 x 8) + (1/2 x 6) = 4 Volume of unit cell (B) : a3 Volume density of atom = A/B = 4/ a3

  13. CRYSTAL STRUCTURE BODY-CENTERED CUBIC Number of atom per unit cell (A) : (1/8 x 8) + 1 = 2 Volume of unit cell (B) : a3 Volume density of atom = A/B = 2/ a3

  14. exercise Find the volume density of atoms in crystal for :- • Figure a, if lattice constant, a = 5 x 10-8cm • Figure b, if lattice constant, a = 4.25 x 10-8 cm Figure a Figure b

  15. CRYSTAL STRUCTURE how to identify types of the wafer?? Is it p-type or n-type wafer?? Is it (100), (111) or (101) orientation??

  16. CRYSTAL STRUCTURE Different plane orientation shows a different shape of wafer

  17. CRYSTAL PLANE Describe the plane shown in this figure ??

  18. CRYSTAL PLANE

  19. CRYSTAL PLANE EXERCISE Figure 1 Figure 2 Describe the plane of the above figure ??

  20. LATTICE PLANE

  21. LATTICE PLANE(miller indices)

  22. EXERCISE

  23. DIRECTION IN CRYSTAL Plane  (hkl) ; Direction  [hkl] Note : for the simple cubic lattice , (hkl) is perpendicular to [hkl]

  24. DIAMOND STRUCTURE(SILICON, germanium) 1/2 0 0 3/4 1/4 1/2 1/2 0 1/4 3/4 • this structure belongs to FCC crystal family • 2 FCC sublattice with one sublattice displaces from the other by one-quarter of the distance • Total number of atom = 8 • 8 corner atoms x 1/8 = 1atom • 6 face atoms x 1/2 = 3 atoms • 4 enclosed atoms = 4 atoms 0 1/2 0

  25. DIAMOND STRUCTURE(SILICON, germanium)

  26. DIAMOND STRUCTURE • Tetrahedral bonding structure • BCC structure with 4 nearest neighbors • This is the basic building block of diamond lattice

  27. ZINCBLENDE STRUCTURE(GALLIUM ARSENIDE) • Zincblende structure is same as diamond structure except it have 2 different types of atom in lattice i.e : Ga and As

  28. ATOMIC BONDING

  29. ATOMIC BONDING

  30. IMPERFECTIONS IN SOLIDS • Lattice imperfection : any deviation from perfect periodic arrangement of lattice points. • Effect : Change electrical and optical properties

  31. IMPERFECTIONS IN SOLIDS Vacancy Interstitial Volume Plane Line dislocation

  32. IMPURITIES IN SOLIDS • Impurities:occurs due to the present of foreign/ impurities atoms especially during doping process (ion implantation / diffusion) • Types :- • Substitutional impurity • Interstitial impurity

  33. GROWTH OF SEMICONDUCTOR CRUCIBLE NO CRUCIBLE

  34. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  35. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  36. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  37. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  38. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  39. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  40. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  41. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  42. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  43. DMT 234 Semiconductor Physic & Device Growth of Semiconductor Materials

  44. DMT 234 Semiconductor Physic & Device • Q & A • Next week Topic :The Semiconductor in Equilibrium.