Electrical Conductivity of Metals

10 Questions

What is the range of resistivity in semiconductors?

10-5 to 106 Ωm

What is the temperature coefficient of resistance in semiconductors?

Negative

What is the primary reason for the decrease in resistivity of semiconductors with temperature?

Increase in charge carrier density

What is the behavior of semiconductors at zero Kelvin?

They act as insulators

What is the advantage of using semiconductors in devices?

Lesser power losses

What is the characteristic of intrinsic semiconductor materials?

They are made up of a single type of element

What is the valence electron configuration of germanium and silicon?

Four valence electrons

What happens to the electrons in intrinsic semiconductor materials when the temperature rises?

Few electrons become unbound and free to move

What is the classification of semiconductors based on their composition?

Intrinsic and extrinsic semiconductors

What is the effect of doping on semiconductor materials?

It modifies them to make semiconductor devices

Study Notes

Conductors of Electricity

Metals like silver, copper, aluminum, gold, and most other metals are excellent conductors of electricity due to their delocalized electrons.
Silver has the highest conductivity, followed by copper and aluminum.
These metals are widely used in electrical wiring, cables, and heat sinks.

Non-Metals as Conductors

Carbon in the form of graphite is an excellent conductor of electricity due to its structure, which allows three out of four carbon atoms to bond, leaving one electron free for bonding.

Ionic Conductors

Conductors in their solution form are called ionic conductors.
Examples of ionic conductors include saltwater, which is a good conductor of electricity due to the movement of ions (charged atoms).

Applications of Conductors

Electrical Wiring: Copper wires are widely used in electrical power transmission and distribution systems due to their high conductivity and ease of use.
Electronic Circuits: Copper traces are used in printed circuit boards (PCBs) to conduct electrical signals between components.
Heat Sinks: Aluminum heat sinks are commonly used in electronic devices to dissipate heat away from hot components like processors.
Electromagnets: Conductors are essential for creating electromagnets used in motors, transformers, and loudspeakers.
Other applications include car radiators, steam or press irons, baking tools, and auto parts industry.

Semiconductors

Semiconductors are materials with conductivity between conductors (metals) and non-conductors (insulators).
Examples of semiconductors include gallium arsenide, germanium, and silicon.
Semiconductors can be used in electronic circuit fabrication, solar cells, laser diodes, and other applications.

Holes and Electrons in Semiconductors

Holes (valence electrons) are positively charged electric charge carriers, while electrons are negatively charged particles.
Electrons have higher mobility than holes due to their different band structures and scattering mechanisms.

Band Theory of Semiconductors

The band theory explains the energy levels of electrons in an atom, which split into multiple levels when combined with other atoms in a solid.
The gap between adjacent bands represents a range of energies that possess no electron, known as the band gap.

Properties of Semiconductors

Semiconductors act like insulators at zero Kelvin but work as conductors at higher temperatures.
Semiconductors can be modified by doping to make semiconductor devices suitable for energy conversion, switches, and amplifiers.
They have lesser power losses, are smaller in size, and possess less weight.

Types of Semiconductors

Intrinsic Semiconductor: Made of a single type of element, like germanium (Ge) and silicon (Si), which are the most common types of intrinsic semiconductor elements.