Presentation for professional english lesson transistors What is a Transistor?

PRESENTATİON FOR PROFESSİONAL ENGLİSH LESSON

Transistors

What is a Transistor?

• Semiconductors: ability to change from conductor to insulator
• Can either allow current or prohibit current to flow
• Useful as a switch, but also as an amplifier
• Essential part of many technological advances

A Brief History

• Guglielmo Marconi invents radio in 1895
• Problem: For long distance travel, signal must be amplified
• Lee De Forest improves on Fleming’s original vacuum tube to amplify signals
• Made use of third electrode
• Too bulky for most applications

The Transistor is Born

• Bell Labs (1947): Bardeen, Brattain, and Shockley
• Originally made of germanium
• Current transistors made of doped silicon

How Transistors Work

• Doping: adding small amounts of other elements to create additional protons or electrons
• P-Type: dopants lack a fourth valence electron (Boron, Aluminum)
• N-Type: dopants have an additional (5th) valence electron (Phosphorus, Arsenic)
• Importance: Current only flows from P to N