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An overview of the phys 3313 semiconductor physics course offered at oklahoma state university. The basics of semiconductors, their crystal structures, and the different types of solids. It also discusses the concept of lattice structures, unit cells, and crystal planes, as well as the different types of atomic bonding. Essential for students enrolled in the phys 3313 course, as it serves as a valuable resource for understanding the fundamental concepts of semiconductor physics.
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PHYS 3313 SEMICONDUCTOR PHYSICS
Course Website: http://physicscourses.okstate.edu/yguo/index.html
syllabus, lecture notes, homework solutions
What are semiconductors?
Materials with electrical conductivities between those of insulators and conductors. Examples: Si, Ge, GaAs
Energy band pictures of conductors, insulators, and semiconductors:
Semiconductor devices: Transistors, switches, diodes, detectors, etc
Overview of the Course:
Ch.1: The crystal structure of solids Describing crystal structure of solids
Ch.2: Introduction to quantum mechanics
Ch.3: Introduction to the quantum theory of solids
Ch.4: The semiconductor in equilibrium
Ch.5: Carrier transport phenomena
Ch.6: Nonequilibrium excess carriers in semiconductors
Ch.7: The pn junction
Ch.8: The pn junction diode
1.2 Types of Solids
Three general types:
1. Amorphous- with order only within a few atomic and molecular dimensions 2. Single crystal- with geometric periodicity throughout the entire material
Fig. 1.
1.3 Space lattices
Lattice: a regular periodic array of lattice points in space to represent the structure of a single crystal Lattice point: a structural unit repeated periodically to form the lattice
Example: Fig. 1.
1.3.1 Primitive and unit cell
Unit cell : a small volume that can be repeated to fill (form) the entire crystal
Primitive unit cell : the smallest unit cell. There is one lattice point per cell.
A unit cell is not unique for a given crystal.
Example: Fig. 1.
1.3.2 Basic crystal structures
Three common types:
Fig. 1.5: structure and conventional unit cells of simple cubic, bcc, and fcc lattice. Volume of the unit cell=a^3 , a=lattice constant (edge of the cell)
Question: What are the number of atoms per unit cell in a simple cubic, bcc, and fcc lattice?
E1.1 The lattice constant of a fcc structure is a=4.75Å. What is the volume density of atoms?
Prob. 1.3(a) Assume that each atom is a hard sphere with the surface of each atom in contact with the surface of its nearest neighbor. Determine the percentage of total unit cell volume that is occupied in a simple cubic lattice.
Knowing the indices (hkl), one can determine:
E1.3 Determine the distance between nearest (110) planes in a simple cubic lattice with a lattice constant of a 0 =4.83 Å (Ans: 3.42 Å)
E1.4 The lattice constant of a fcc structure is 4.75 Å. Calculate the surface density of atoms for (a) a (100) plane and (b) a (110) plane
1.3.4 The diamond structure
Figure 1.
The zincblende structure: two different types of atoms in the lattice. Example: compound semiconductors such as GaAs Fig. 1.
Figure 1.
1.4 Atomic bonding
What holds a crystal together?
The attractive electrostatic interaction between electrons and nuclei.
Why one particular crystal structure is favored over another for a given type of atoms?
Total energy of the system tends to reach a minimum value.
Thus, the crystal structure is closed related to atomic interactions/bonding.
1.5 Imperfections and impurities in solids
1.5.1 Imperfections in solids
Point defects:
Line dislocation- a row of atoms missing (Fig. 1.18)
1.5.2 Impurities in solids
Doping: adding impurities to change conductivity of the semiconductor material.
