EE3950_Class_Notes_Chapter_10

EE3950_Class_Notes_Chapter_10 - Semiconductors Semicond...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Semiconductors Crystalline solid materials whose resistivities are values between those of conductors and sulators insulators. Good electrical characteristics and feasible fabrication technology are some reasons why silicon is by far the most important semiconductor material in use today. Compound semiconductor materials such as gallium arsenide are used in photonic and icrowave applications, and germanium is microwave applications, and germanium is used for a few special purposes.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Semiconductors Silicon atoms join together to form a regular three dimensional structure called a crystal lattice. Pure semiconductor materials, termed uese co duc to a te as ,te ed intrinsic semiconductors, are neutral in tal charge and are also a poor tota c a ge a d a e a so a poo conductor of electricity. This means they have very few charge carriers. yyg
Background image of page 2
Intrinsic Semiconductor
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Doping Process that adds a small amounts of impurities, dopants, to a semiconductor, so at it can be made to contain a desired that it can be made to contain a desired number of either holes or free electrons. After the doping process the materials generated are termed extrinsic semiconductors. They are impure. Impurities are classified as either: ± Donor. cceptor ± Acceptor.
Background image of page 4
Extrinsic Semiconductors Donor impurities donate extra electrons to the silicon lattice: ± Antimony, Arsenic and Phosphorus. They have 5 electrons in their outer electron shell. Four of them will be used in the covalent bonds to the neighboring silicon toms but the fifth can be easily freed from atoms, but the fifth can be easily freed from their original atoms by thermal energy even at room temperatures.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
N-Type Semiconductor Semiconductor materials doped to contain excess free electrons are considered n-type semiconductors. Even though the added impurity created xcess free electrons the material is still excess free electrons, the material is still neutral in charge. has been found that in n pe materials the It has been found that in n-type materials the free electron concentration is approximately qual to the donor atom doping density: equal to the donor atom doping density: ± n N D
Background image of page 6
N-Type Semiconductor
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Extrinsic Semiconductors Acceptor impurities create a hole in the silicon lattice: ± Boron, Gallium and Indium. hey have 3 electrons in their outer They have 3 electrons in their outer electron shell, and they are not enough fill all the orbitals around it. This to fill all the orbitals around it. This leaves a bond site empty, and this mpty place is called a hole. empty place is called a hole.
Background image of page 8
P-Type Semiconductor Semiconductor materials doped to contain excess holes are considered p-type miconductors semiconductors. Even though the added impurity created excess holes, the material is still neutral in charge.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/08/2011 for the course EE 3950 taught by Professor Desoza during the Spring '08 term at LSU.

Page1 / 60

EE3950_Class_Notes_Chapter_10 - Semiconductors Semicond...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online