What are pentavalent and trivalent impurities?

Pentavalent impurities Impurity atoms with 5 valence electrons produce n-type semiconductors by contributing extra electrons. Trivalent impurities Impurity atoms with 3 valence electrons produce p-type semiconductors by producing a “hole” or electron deficiency.

What are the pentavalent impurities?

Pentavalent impurities are the atoms with five valence electrons used for the doping of semiconductors. i.e. Arsenic (As), Phosphorous (Pi), Antimony (Sb), etc. Arsenic is an example for pentavalent impurity. They have 5 valence electrons.

What is a trivalent material?

Trivalent impurity atoms have 3 valence electrons. The various examples of trivalent impurities include Boron (B), Gallium (G), Indium(In), Aluminium(Al). Boron is a substance consisting of atoms which all have the same number of protons.

What is tetravalent impurity?

When a tetravalent atom such as Si or Ge is doped with a trivalent impurity such as Al, B, In, etc., the dopant atom has one less electron than the surrounding atoms of Si or Ge. Thus, the fourth atom of the tetravalent atom is free and a hole or a vacancy is generated in the trivalent atom.

Is gallium a trivalent impurity?

Example of trivalent impurity are Boron, Gallium and Indium. Trivalent impurity like boron, have 3 valence electrons. Each atom of the impurity fits in the silicon crystal by forming covalent bonds with the surrounding silicon atoms.

What are pentavalent elements?

Pentavalent elements are those elements which have five electrons in their outer shell. Since electrons are negative charge carriers, the resultant material is called an n-type (or negative type) semiconductor. The pentavalent impurity that is added is called a ‘dopant’ and the process of addition is called ‘doping’.

Is Gallium a trivalent impurity?

What are pentavalent dopants?

A dopant with five valence electrons is also called a pentavalent impurity. Other pentavalent dopants are antimony (Sb) and bismuth (Bi). At room temperature, the liberated electron can move around the Si crystal and carry a current, thus acting as a charge carrier.

Why are trivalent impurities called acceptor impurities?

It has the ability by which it can accept an electron from neighbouring atom as it has a vacancy of electron. Thus is called acceptor impurity. So, the presence of excess positive charge forms the p-type region. Elements like boron, aluminium, indium and gallium are examples of trivalent impurity.

How does a trivalent impurity modify an intrinsic semiconductor?

Doping is the process of adding impurities to intrinsic semiconductors to alter their properties. When an intrinsic semiconductor is doped with Trivalent impurity it becomes a P-Type semiconductor. The P stands for Positive, which means the semiconductor is rich in holes or Positive charged ions.

Which of the following is trivalent impurity?

The various examples of trivalent impurities include Boron (B), Gallium (G), Indium(In), Aluminium(Al). Boron is a substance consisting of atoms which all have the same number of protons.

Which is not trivalent impurity atom?

phosphorus is a Pentavalent i.e. they are having 5 elections in the valence band.