Intrinsic vs. Extrinsic Semiconductors: Key Differences
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This article explains the key differences between intrinsic and extrinsic semiconductors. Let’s dive in!
What is a Semiconductor?
A semiconductor is a crucial component in modern electronics, possessing an electrical conductivity that falls between highly conductive metals and insulating materials. Think of it as a “Goldilocks” material – not too conductive, not too resistive, but just right!
Here’s a breakdown of key semiconductor characteristics:
- Conductivity: Their resistivity lies between conductors and insulators.
- Temperature Coefficient: They exhibit a negative temperature coefficient of resistance, meaning their conductivity increases as temperature rises.
- Impurity Sensitivity: Their conductivity is significantly affected by the presence of impurities within the crystal lattice.
Semiconductors are fundamental to a vast array of solid-state devices, including transistors, integrated circuits (ICs), diodes, photodiodes, and LEDs. Common semiconductor materials include Germanium and Silicon.
More semiconductor characteristics:
- Crystalline Structure: Semiconductors possess an organized, crystalline structure at the atomic level.
- Light Sensitivity: Their conductivity is dramatically influenced by light rays of high intensity (ultraviolet and infrared).
- Temperature Dependence: Conductivity changes based on temperature variations.
Intrinsic Semiconductors: The Pure Form
An intrinsic semiconductor is simply a semiconductor material in its absolutely pure form. It contains no significant impurities.
Extrinsic Semiconductors: Enhanced with Impurities
An extrinsic semiconductor, on the other hand, is a semiconductor material to which other elements have been intentionally added. This process, known as doping, alters the semiconductor’s electrical properties. Examples of extrinsic semiconductors include N-type and P-type materials.
P-Type Material: Adding Trivalent Elements
P-type material is created when a trivalent element (an element with three valence electrons, such as Indium or Gallium) is added to a tetravalent semiconductor (like Germanium or Silicon). This results in a “deficit” of electrons – essentially, “holes” – for each impurity atom. These holes act as positive charge carriers.
N-Type Material: Adding Pentavalent Elements
N-type material is created when a pentavalent element (an element with five valence electrons, like Arsenic or Antimony) is added to a tetravalent semiconductor. This creates a surplus of electrons provided by each impurity atom. These excess electrons act as negative charge carriers.
Key Differences Summarized
Feature | Intrinsic Semiconductor | Extrinsic Semiconductor |
---|---|---|
Purity | Pure form | Impurities added (doped) |
Conductivity | Lower conductivity | Higher conductivity |
Charge Carriers | Equal number of electrons and holes | Unequal number of electrons and holes |
Examples | Pure Silicon, Pure Germanium | N-type Silicon, P-type Germanium |