Question

Fill in the blanks.
Trivalent impurity is called __________ impurity.

Answer 1

Hint:Trivalent impurities are the doping materials having three electrons in the outermost shell of the atom. Pure semiconductors are converted into p and n types of the semiconductor by doping. These semiconductors are more conductive than pure semiconductors. The impurities which accept electrons are also known as acceptor impurities.

Complete step-by-step solution:Semiconductors are the material having four valence electrons in the outermost shell. These elements cannot lose electrons or gain four electrons. Rather, these elements share the electrons with other atoms of the same elements. When the elements are combined with the element of the same element then they are known as the intrinsic semiconductors. Intrinsic semiconductors have very low conductivity. To make the intrinsic semiconductor conductive, the temperature of the intrinsic semiconductor is increased to very high value.
Trivalent impurities contribute a greater number of holes to semiconductor crystals, and these holes can accept electrons, these impurities are referred to as acceptor impurities. For trivalent impurity, since the trivalent atoms have valency as three that is, it is an element in which each atom has three valence electrons. For example, Indium, Gallium, Aluminum, Boron, etc. As trivalent impurities accept electrons from the covalent bonds of Si, Ge they create p type semiconductor. Thus, trivalent impurity is called Acceptor impurities.

Note:Intrinsic semiconductors are doped with pentavalent impurities. The electrons are produced in the semiconductor and this semiconductor is known as n type semiconductor. Intrinsic element is doped with trivalent impurity to convert it to p type semiconductor. P-type semiconductors are created by addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor that creates deficiencies of valence electrons.