File Name: n type and p type semiconductor .zip
Show all documents When placed in contact, some of the electrons in the n - type portion flow into the p- type to "fill in" the missing electrons, also known as electron holes. Eventually enough electrons will flow across the boundary to equalize the Fermi levels of the two materials.
- Intrinsic and extrinsic N-type & p-type Semi Conductors
- I. P-Type, N-Type Semiconductors
- Basics of Semiconductor Diodes
Intrinsic and extrinsic N-type & p-type Semi Conductors
We know that the p-type and n-type semiconductors come under extrinsic semiconductors. The classification of the semiconductor can be done based on doping like intrinsic and extrinsic as per the matter of purity concerned. There are many factors that generate the main difference between these two semiconductors. The formation of p-type semiconductor material can be done by adding the group III elements. Similarly, the n-type semiconductor material can be formed by adding group V elements. This article discusses the difference between P-type semiconductor and N-type semiconductor. The P-type semiconductor can be defined as, once the trivalent impurity atoms such as indium, gallium are added to an intrinsic semiconductor, and then it is known as a p-type semiconductor.
An extrinsic semiconductor is one that has been doped ; during manufacture of the semiconductor crystal a trace element or chemical called a doping agent has been incorporated chemically into the crystal, for the purpose of giving it different electrical properties than the pure semiconductor crystal, which is called an intrinsic semiconductor. In an extrinsic semiconductor it is these foreign dopant atoms in the crystal lattice that mainly provide the charge carriers which carry electric current through the crystal. The doping agents used are of two types, resulting in two types of extrinsic semiconductor. An electron donor dopant is an atom which, when incorporated in the crystal, releases a mobile conduction electron into the crystal lattice. An extrinsic semiconductor which has been doped with electron donor atoms is called an n-type semiconductor , because the majority of charge carriers in the crystal are negative electrons. An electron acceptor dopant is an atom which accepts an electron from the lattice, creating a vacancy where an electron should be called a hole which can move through the crystal like a positively charged particle. An extrinsic semiconductor which has been doped with electron acceptor atoms is called a p-type semiconductor , because the majority of charge carriers in the crystal are positive holes.
I. P-Type, N-Type Semiconductors
A semiconductor which is pure and contains no impurity is known as an intrinsic semiconductor. In an intrinsic semiconductor, the number of free electrons and holes are equal. Common examples of intrinsic semiconductors are pure germanium and silicon. Schematic band diagram of an intrinsic semiconductor at room temperature is represented. Fig, Energy band diagram of an intrinsic semiconductor. An extrinsic semiconductor is one in which an impurity with a valency higher or lower than the valency of the pure semi conductoris added, so as to increase the electrical conductivity of the semiconductor. Depending upon the type of impurity atoms added, an extrinsic semiconductor can be classified as N-type or P-type.
Semiconductors are materials that have properties of both normal conductors and insulators. Semiconductors fall into two broad categories:. In the classic crystalline semiconductors, electrons can have energies only within certain bands ranges of energy levels. The energy of these bands is between the energy of the ground state and the free electron energy the energy required for an electron to escape entirely from the material. The energy bands correspond to a large number of discrete quantum states of the electrons. Most of the states with low energy closer to the nucleus are occupied, up to a particular band called the valence band.
It is possible to shift the balance of electrons and holes in a silicon crystal lattice by "doping" it with other atoms. Atoms with one more valence electron than silicon are used to produce " n -type" semiconductor material. Therefore, more electrons are added to the conduction band and hence increases the number of electrons present. Atoms with one less valence electron result in " p -type" material. Therefore, p -type material has only 3 valence electrons with which to interact with silicon atoms. The net result is a hole, as not enough electrons are present to form the 4 covalent bonds surrounding the atoms. In p -type material, the number of electrons trapped in bonds is higher, thus effectively increasing the number of holes.
N-Type and P-Type Semiconductors. 1–5. The PN Each type of atom has a certain number of electrons and protons that distinguishes it from the atoms of all.
Basics of Semiconductor Diodes
The process of purposefully adding impurities to materials is called doping; semiconductors with impurities are referred to as "doped semiconductors". In a pure intrinsic Si or Ge semiconductor, each nucleus uses its four valence electrons to form four covalent bonds with its neighbors see figure below. Since there are no excess electrons or holes In this case, the number of electrons and holes present at any given time will always be equal. An intrinsic semiconductor. Now, if one of the atoms in the semiconductor lattice is replaced by an element with three valence electrons, such as a Group 3 element like Boron B or Gallium Ga , the electron-hole balance will be changed.
The various factors like doping element, nature of doping element, the majority and minority carriers in the p-type and n-type semiconductor. The density of electrons and holes, energy level and Fermi level, the direction of movement of majority carriers, etc. The difference between a p-type semiconductor and an n-type semiconductor is given below in the tabulated form. The p-type semiconductor is formed when the Trivalent impurity is added to the pure semiconductor. Similarly, when a Pentavalent impurity is added to the pure semiconductor n-type semiconductor is obtained.
The addition of a small percentage of foreign atoms in the regular crystal lattice of silicon or germanium produces dramatic changes in their electrical properties, producing n-type and p-type semiconductors. Pentavalent impurities Impurity atoms with 5 valence electrons produce n-type semiconductors by contributing extra electrons.
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