p type and n type semiconductor materials pdf

P Type And N Type Semiconductor Materials Pdf

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It is possible to shift the balance of electrons and holes in a silicon crystal lattice by "doping" it with other atoms.

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.

I. P-Type, N-Type Semiconductors

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.

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.

Difference between P-type Semiconductor and N-type Semiconductor

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. Trivalent impurities Impurity atoms with 3 valence electrons produce p-type semiconductors by producing a " hole " or electron deficiency. The addition of pentavalent impurities such as antimony, arsenic or phosphorus contributes free electrons, greatly increasing the conductivity of the intrinsic semiconductor. Phosphorus may be added by diffusion of phosphine gas PH3. The addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor creates deficiencies of valence electrons, called "holes".

Difference Between p Type and n Type Semiconductor

October 01, Ebreo, Phoebe Ms. Before understanding several devices like Semiconductor Diodes, Transistors, etc. This means that they have a resistivity too low to be called an insulator but at the same time, too high to be called a conductor. There are two types of semiconductor components in electronic and electrical circuits.

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 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.

The Doping of Semiconductors

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