Arrange the following materials in order of increasing electrical conductivity. (a) Cu (b) Al2O3 (c) Fe (d) Pure Ge (e) Ge doped with In

Verified step by step guidance

1. Identify the type of materials: metals, semiconductors, and insulators.
2. Recognize that metals like Cu (copper) and Fe (iron) have high electrical conductivity due to free electrons.
3. Understand that Al2O3 (aluminum oxide) is an insulator with very low electrical conductivity.
4. Note that pure Ge (germanium) is a semiconductor with moderate conductivity, which increases when doped with elements like In (indium).
5. Arrange the materials from lowest to highest conductivity: Al2O3, pure Ge, Ge doped with In, Fe, Cu.

Key Concepts

Electrical Conductivity

Electrical conductivity is a measure of a material's ability to conduct electric current. It depends on the presence of free charge carriers, such as electrons or ions, and is influenced by the material's structure and temperature. Metals typically have high conductivity due to their abundance of free electrons, while insulators have low conductivity.

Semiconductors and Doping

Semiconductors, like germanium (Ge), have electrical conductivity between that of conductors and insulators. Their conductivity can be significantly enhanced through a process called doping, where impurities (like indium in this case) are added to create more charge carriers. This allows semiconductors to be tailored for specific electronic applications.

Oxides and Conductivity

Metal oxides, such as aluminum oxide (Al2O3), generally exhibit low electrical conductivity because they lack free electrons. They are often used as insulators in electronic devices. Understanding the conductivity of oxides is crucial when comparing them to metals and doped semiconductors, as their behavior in electrical applications differs significantly.