What is done to create an extrinsic semiconductor?
a) stimulated emission.
b) increase the band-gap of the material
c) doping the material with impurities
d) refractive index is decreased
The answer is C, which is doping the material with impurities. Simply said, this is because an intrinsic semiconductor is a pure semiconductor. To create an extrinsic semiconductor, atoms of an impurity are inserted into the material during the doping process. These impurity atoms release electrons or holes, depending on the impurity.
What is extrinsic semiconductor?
A semiconductor that has been doped is referred to as an extrinsic semiconductor. This means that during the manufacturing process of the semiconductor crystal, a trace element or chemical known as a doping agent was incorporated chemically into the crystal with the intention of giving it different electrical properties than those of a pure semiconductor crystal, which is referred to as an intrinsic semiconductor. In an extrinsic semiconductor, the charge carriers that allow electric current to flow through the crystal are predominantly provided by the foreign dopant atoms that are embedded within the crystal lattice. Because there are two distinct kinds of doping agents used, the end product is two distinct kinds of extrinsic semiconductor.
When a certain type of atom is incorporated into a crystal, it gives off a mobile conduction electron into the crystal’s lattice. This type of atom is known as an electron donor dopant. An n-type semiconductor is an extrinsic semiconductor that has been doped with electron donor atoms. This is because electrons, which are regarded as negative charge carriers, make up the majority of charge carriers in the crystal. An electron acceptor dopant is an atom that takes an electron from the lattice and moves it to itself, thereby creating a hole in the lattice. A hole is a vacancy in the lattice that can be thought of as a positively charged particle that can move through the crystal. A p-type semiconductor is an extrinsic semiconductor that has been doped with electron acceptor atoms. This is because the majority of charge carriers in the crystal are positive holes, which gives the semiconductor its p-type designation.
Electronic components like diodes, transistors, integrated circuits, semiconductor lasers, LEDs, and photovoltaic cells are all made with extrinsic semiconductors. Extrinsic semiconductors are employed to create semiconductor electronic devices because doping is the secret to the extraordinarily diverse variety of electrical behavior that semiconductors can display. Creating semiconductor devices on the surface of a semiconductor wafer can be accomplished through the use of complex semiconductor fabrication processes such as photolithography. These processes can implant different dopant elements in various regions of the same semiconductor crystal wafer. For instance, the n-p-n bipolar transistor is a common type of transistor. It is made up of an extrinsic semiconductor crystal with two regions of n-type semiconductor, which are separated by a region of p-type semiconductor. Metal contacts are attached to each part of the crystal.
Conduction in Semiconductors
A solid substance can only conduct electric current if it contains charged particles called electrons that are free to move around and are not attached to the atoms that make up the substance. The electrons in a metal conductor come from the metal atoms; normally, each metal atom releases one of its outer orbital electrons to transform into a conduction electron, which can move freely inside the crystal and convey an electric current. Because of this, the number of conduction electrons in a metal is equal to the number of atoms, which is a very large number. As a result, metals are excellent conductors of electricity. In contrast to metals, the atoms that make up the bulk of the semiconductor crystal do not supply the electrons that are responsible for the conduction of electrical current. The mobile charge carriers, either electrons or holes, are responsible for the electrical conduction in semiconductors.
The transformation of an intrinsic semiconductor into an extrinsic semiconductor is accomplished through a process known as doping a semiconductor. An intrinsic semiconductor can have impurity atoms added to it through a process called doping. In a semiconductor, impurity atoms are atoms of a different element than the intrinsic semiconductor’s atoms themselves. Impurity atoms can interact with the intrinsic semiconductor in one of two ways: as either donors or acceptors. This causes a shift in the intrinsic semiconductor’s electron and hole concentrations. On the basis of the effect that they have on the intrinsic semiconductor, impurity atoms can be categorised as either donor atoms or acceptor atoms. In the intrinsic semiconductor lattice, donor impurity atoms have a greater number of valence electrons than the atoms that they replace. Donor impurities provide excess electrons to the intrinsic semiconductor by “donating” their extra valence electrons to the conduction band of a semiconductor. The electron carrier concentration (n0) of increases as a result of excessive electrons.
An element is classified as a semiconductor or a dopant atom depending on which column of the periodic table it is located in. The column definition of the semiconductor establishes the number of valence electrons that its atoms possess as well as the role that dopant atoms play in the semiconductor, either as donors or acceptors. Group IV semiconductors rely on atoms from group V as their donors and atoms from group III as their acceptors. Compound semiconductors, which fall under the category of group III–V semiconductors, make use of atoms from group VI as donors and atoms from group II as acceptors. Group III–V semiconductors have the additional capability of employing group IV atoms in either the donor or acceptor role. If an atom from group IV were to take the place of an element from group III in a semiconductor lattice, the group IV atom would function as a donor. On the other hand, if an atom from group IV were to replace an element from group V, the group IV
- Extrinsic semiconductor – Wikipedia