P Type And N Type Materials Pdf
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- Formation of a PN-Junction
- Basics of Semiconductor Diodes
- Drastic Improvement of Air Stability in an n-Type Doped Naphthalene-Diimide Polymer by Thionation
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.
Organic thermoelectrics are attractive for the fabrication of flexible and cost-effective thermoelectric generators TEGs for waste heat recovery, in particular by exploiting large-area printing of polymer conductors. Here we tackle this problem in a relevant class of electron transporting, naphthalene-diimide copolymers, by substituting the imide oxygen with sulfur. This result highlights the effectiveness of chemical tuning to improve air stability of n-type solution-processable polymer conductors and shows a path toward ambient large-area manufacturing of efficient polymer TEGs. Energy harvesting with organics sees its most mature example in organic solar cells, which enable lightweight and large-area solar energy converters suitable for distributed energy generation.
Formation of a PN-Junction
Pure semiconductors are relatively good insulators as compared with metals, though not nearly as good as a true insulator like glass. To be useful in semiconductor applications, the intrinsic semiconductor pure undoped semiconductor must have no more than one impurity atom in 10 billion semiconductor atoms. This is analogous to a grain of salt impurity in a railroad boxcar of sugar. Impure, or dirty semiconductors are considerably more conductive, though not as good as metals. Why might this be? To answer that question, we must look at the electron structure of such materials in Figure below.
In this tutorial, we will learn about an introduction to semiconductors as they are an essential part of Electronics. Before understanding several devices like Semiconductor Diodes, Transistors, etc. This part of the tutorial will lay out a key foundation in easily learning the PN Junction, which is next in line. There are two types of semiconductor components in electronic and electrical circuits. They are active and passive components. Diodes are the foremost active components and resistors are the foremost passive components in electronic design circuits. Diodes are essentially unidirectional devices having exponential relationship for the current-voltage characteristics are made from semiconductor materials.
Basics of Semiconductor Diodes
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.
P-n junctions are formed by joining n -type and p -type semiconductor materials, as shown below. Since the n -type region has a high electron concentration and the p -type a high hole concentration, electrons diffuse from the n -type side to the p -type side. Similarly, holes flow by diffusion from the p -type side to the n -type side. If the electrons and holes were not charged, this diffusion process would continue until the concentration of electrons and holes on the two sides were the same, as happens if two gasses come into contact with each other. However, in a p-n junction, when the electrons and holes move to the other side of the junction, they leave behind exposed charges on dopant atom sites, which are fixed in the crystal lattice and are unable to move.
In simple words, an intrinsic semiconductor is one which is made up of a very pure semiconductor material. In more technical terminology it can.
Drastic Improvement of Air Stability in an n-Type Doped Naphthalene-Diimide Polymer by Thionation
Doping means the introduction of impurities into a semiconductor crystal to the defined modification of conductivity. Other materials are aluminum, indium 3-valent and arsenic, antimony 5-valent. The dopant is integrated into the lattice structure of the semiconductor crystal, the number of outer electrons define the type of doping. Elements with 3 valence electrons are used for p-type doping, 5-valued elements for n-doping.
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В два часа ночи по воскресеньям. Она сейчас наверняка уже над Атлантикой. Беккер взглянул на часы. Час сорок пять ночи. Он в недоумении посмотрел на двухцветного.
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