Intrinsic vs. Extrinsic Semiconductors: Key Differences

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