Semiconductor P-N Junctions: Transistors or Diodes?

In summary, a semiconductor with a p-n junction is considered a diode, not a transistor. Transistors must have three terminals and are essentially constructed by combining two p-n junctions. A triode is a type of vacuum device that functions similarly to a transistor. While transistors are solid state devices, triodes are not. Some people prefer to use tube-amps, which are made with triodes, for better sound quality.
  • #1
cscott
782
1
Is a semiconductor with a p-n junction considered a transistor or just a diode? If it is just a diode, are transistors always triodes?
 
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  • #2
Not my area, but... as far as I know a transistor has to be at least a triode because you need to input the control voltage.
 
  • #3
cscott said:
Is a semiconductor with a p-n junction considered a transistor or just a diode?
It is a diode, not a transistor. It has greater conductivity in one direction than the other.
If it is just a diode, are transistors always triodes?
A triode is a vacuum device that works essentially like a transistor. It is not a solid state device.

A transistor must have three terminals. The idea is that by applying a (gate) voltage at one of the terminals, you can control the current flowing between the other two. The BJT is constructed essentially by sticking a pair of p-n junctions together, making sure the middle layer (the base) is really thin.
 
  • #4
Oh, ok. Thanks!
 
  • #5
Thanks for the clarification on the triode, Gokul. I always thought that it was just anything with 3 leads.
 
  • #6
Danger said:
Thanks for the clarification on the triode, Gokul. I always thought that it was just anything with 3 leads.
Ever worked with tube-amps ? People still like to build their amplifiers out of triodes for better sound quality.
 
  • #7
I've never worked with any electronics. As my post should tell you, I know almost nothing about it. :redface: The closest that I got was changing burned-out tubes in my TV (yes, I'm that old :grumpy: ). I've heard very often that audiophiles pay big bucks for tube amps because they provide a 'warmer' sound. I guess the closest analogy that I can think of is that of a very good painting (tubes) as opposed to a photo (solid-state).
 

1. What is a semiconductor P-N junction?

A semiconductor P-N junction is a boundary between two types of semiconductor material, one with an excess of positive charges (P-type) and one with an excess of negative charges (N-type). This junction creates unique electrical properties that are essential for the operation of transistors and diodes.

2. How do transistors and diodes utilize semiconductor P-N junctions?

Transistors and diodes use the properties of the P-N junction to control the flow of electrons and create an electric current. In transistors, the P-N junction acts as a switch to amplify and control the flow of current, while in diodes it acts as a one-way valve, allowing current to flow in only one direction.

3. What are the key components of a semiconductor P-N junction?

The key components of a semiconductor P-N junction are the P-type and N-type semiconductor materials, the depletion region (an area with no free charges), and the built-in electric field. These components work together to create unique electrical properties at the junction.

4. How do impurities affect the properties of a semiconductor P-N junction?

Impurities, also known as dopants, are intentionally added to the semiconductor materials to create the P-type and N-type regions. The type and concentration of impurities can greatly influence the electrical properties of the junction, allowing for precise control and manipulation of current flow in transistors and diodes.

5. What are some practical applications of semiconductor P-N junctions?

Semiconductor P-N junctions are used in a wide range of electronic devices, including transistors, diodes, LED lights, solar cells, and integrated circuits. They are also essential components in computer processors and other digital devices, making them crucial for modern technology.

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