[ AETN2101 ] 1 - Semiconductors

Valence Electrons

Electrons that occupy the outermost shell of an atom

Eight.

How many valence electrons are typically found in the best insulators?

Gold, Silver, Aluminum, and Copper.

List four examples of conductive materials mentioned in the text.

Silicon (Si).

Which material is identified as the most commonly used semiconductor due to its abundance on Earth?

Four.

How many valence electrons are present in both Silicon (Si) and Germanium (Ge) atoms?

The third shell.

In which atomic shell are the valence electrons of a Silicon atom located?

Fourth

In which atomic shell are the valence electrons of a Germanium atom located?

Silicon.

Between Silicon and Germanium, which atom's valence electrons are closer to the nucleus?

The current decreases.

How does an increase in temperature affect the electric current in a conductor?

Atomic vibration.

What physical phenomenon caused by temperature increases opposes the flow of electrons in a conductor?

The current increases.

How does an increase in temperature affect the electric current in a semiconductor?

Doping

The process of adding controlled impurities to an intrinsic semiconductor to increase conductivity.

Extrinsic Material

A semiconductor material that has been modified through the addition of impurity atoms.

Five (pentavalent).

How many valence electrons are found in the impurity atoms used to create n-type material?

They provide an extra mobile electron that does not bond with neighboring silicon atoms.

Why are pentavalent impurity atoms referred to as 'donors'?

Antimony (Sb).

Which pentavalent element is specifically mentioned as an n-type impurity?

Electrons.

In n-type semiconductor material, what are the majority carriers?

Holes.

In n-type semiconductor material, what are the minority carriers?

Three (trivalent).

How many valence electrons are in the impurity atoms used to create p-type material?

Boron (B), Gallium (Ga), and Indium (In).

List three trivalent materials commonly used as additives for p-type semiconductors.

They are continually accepting extra or free electrons because they create holes in the lattice.

Why are trivalent impurities called 'acceptor atoms'?

Majority

In p-type materials, positive holes are designated as the _____ carriers.

Minority

In p-type materials, free electrons are designated as the _____ carriers.

A PN junction.

What is formed when a p-material and an n-material are joined together?

They move to the p-region and fall into holes.

During the formation of a PN junction, where do conduction electrons from the n-region move to?

A positive ion.

What type of ion is left behind in the n-region after an electron migrates to the p-region during junction formation?

Negative

When an electron fills a hole in the p-region near a junction, it creates a _____ ion.

Depletion Region

A thin area at the PN boundary depleted of free charges that prevents further charge migration.

True.

True or False: In a semiconductor, vibrating atoms oppose only a few electrons while a large number flow freely.

The state and number of its valence electrons.

What is the primary factor that determines a material's ability to conduct electricity?

Boron (B).

Which trivalent additive is identified as 'commonly used' in the provided text?

Negative

The excess of current-carrying electrons in n-type material gives the majority carriers a _____ charge.

When its single valence electron escapes to the conduction band.

Under what condition is an atom referred to as a 'positive ion' or 'core' in a conductor like Copper?

Semiconductors are generally poorer conductors than pure metals.

Compare the conductivity of pure semiconductors to that of conductors.

Four.

How many orbital electrons from a pentavalent impurity bond with neighboring Silicon atoms in n-type material?