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Doping with Group III elements, which are missing the fourth valence electron, creates "broken bonds" (holes) in the silicon lattice that are free to move. The result is an electrically conductive p-type semiconductor.
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Why intrinsic semiconductor is not used in practical applications?
we dont get an appreciable current in dis case...dats why we dope n get curret for practical use...
How does doping effect the depletion layer in a semiconductor?
A semiconductor has an energy band (a range of energy levels) that is forbidden -- ideally void of charged particles at all temperatures. Practically, at low temperatures (T < 40 K for silicon), the probability of finding a free charge carrier outside the forbidden gap is nearly nil. When the temperature is increased, the probability of finding a free charge carrier outside the forbidden gap increases, but the net charge is still zero (negative charge exactly cancels positive charge). However, an intrinsic semiconductor (pure or undoped) is just a resistor of little importance (other materials are cheaper and better-controlled than a semiconductor). When we introduce foreign atoms into a semiconductor (the process is called doping), we change its electrical properties -- it has a lot more free charge carriers than an intrinsic semiconductor, although again, the net charge is zero. The total charge of free carriers is balanced by immobile ions of equal and opposite total charge. For example, boron and indium will be used to dope silicon p-type; phosphorus and arsenic will be doping silicon n-type. I am quoting boron, phosphorus, and silicon as examples from hereon. p-type doping is a process where a silicon atom in the lattice is replaced by a boron atom. A Boron atom has 3 electrons in the outer shell, compared with an electron occupancy of 4 for a silicon atom. So a Boron atom provides a vacancy for any free electrons to occupy with a little effort, when an electron chances to be nearby (the four boron-silicon covalent bonds needs 8 electrons to be stable, but only 7 are provided). The net charge of the material is still zero. More about from where the free electron is coming. n-type doping is using a phosphorus atom to replace a silicon atom. A phosphorus atom has 5 electrons in the outer shell. So a phosphorus atom provides an electron that can be freed with a little effort (the four phosphorus-silicon covalent bonds only need 8 electrons to be stable, each atom needing only to contribute four electrons; the 9th electron will be loosely bound). The net charge of the material is still zero. Where can the electron go? Magic happens when a p-type silicon is brought in contact with an n-type silicon to form a pn junction. The excess electron vacancies (holes) in p-Si now can exchange with the excess electrons in n-Si, but the net charge of the p-n silicon entity is still zero. However, microscopically, a depletion region is formed at the pn junction, where excess carriers can cross over to the other side. In the p-Si, excess electrons from the n-Si start filling up the holes (the lack of the 8th outer-shell electron to form the four stable boron-silicon covalent bonds) and negatively-charged boron atoms are formed. In the n-Si, excess holes from the p-Si start swallowing up the loosely-bound electrons (the 9th electron in the outer shell) of phosphorus atoms and positively-charged phosphorus atoms are formed. Once formed, and in the absence of an electric field, the depletion region now presents an energy barrier to any further carrier movement and a steady state results -- no net current in the pn junction.
How can avalanche breakdown be avoided in FET?
Breakdown depends on the electric field value in FETS (as in diodes and such, where you can find a junction). Theoretically, you need to - dope less the junction region of your device (like p-i-n diodes, the i (intrinsic) region is not doped in order to reduce E field peak, which occurs near the center of the device). - raise the length of your device Both of these two solutions will have the drawback of increasing your ON resistance. At circuit design level, you can protect your devices with clamp diodes or something similar.
How do you replace heating elements on electric hot water heater?
most water heaters rust out from the bottom or at he top where the pipes lead into them. the amount of time and effort to try and fabricate a fix would not serve the owner unless he had no choice. replacing the unit is the standard way to fix these.sometimes the gas regulator can go bad and these can be replaced.
How is p type semiconductor formed?
p-type or n-type semiconductor alone is of very limited use in chips -- you can only make a thin-film resistor or parallel-plate capacitor with it. You also need the opposite type, the n-type semiconductor, to make junction diodes and MOS or bipolar transistors, which are essential components in an integrated circuit. ================================
What type of semiconductor is obtained when silicon is doped with arsenic?
A semiconductor of silicon doped with a pentavalent impurity expected to be an n-type semiconductor.When you dope a silicon semiconductor with pentavalent impurity the extra electron from the pentavalent compound remains free while others 4 form the covalent bonding with neighboring atoms leaving one unpaired electron.The extra electron remains in the higher energy state nearer to the conduction band, and, depending on the material, a small amount of energy can bring the electron to the conduction band and hence electron acts as the carrier. Thus an n-type of semiconductor is formed.
If you want to dope Ga As to make a p-type semiconductor with an element to replace As which elements would you pick?
Ge
Why intrinsic semiconductor is not used in practical applications?
we dont get an appreciable current in dis case...dats why we dope n get curret for practical use...
What is the concept of a hole in semiconductors?
A semiconductor material forms a crystal structure where all the valence electrons "participate" in forming the lattice. There are neither "extra" nor "missing" electrons in the structure. If we dope the semiconductor with a "P-type" material, this sets the stage for the creation of a "hole" in that matrix. The P-type material will have one less valence electron than our semiconductor material. And when that P-type atom becomes part of the crystal matrix, it lacks that one electron to make the matrix "complete" or "uniform" as regards the electrons. That creates the hole in the matrix. When that P-type material is formed up against N-type material (which has an "extra" electron in its matrix), that extra electron will leave the N-type material and migrate to the P-type material to fill that hole. This sets up a condition where charges have shifted, and it creates a difference of potential (voltage) across the junction (owing to the shift of the electrons).
What are semiconductors?
Semiconductors are insulators at low temperatures and reasonably good conductors at higher temperatures.semiconductors whose ability to conduct electric lies between those of conductor and insulatorAdditional:Common semiconductors include silicon and germanium, which are tetra-valent, that is each atom has four electrons in its outer orbit. In the normal crystalline form, the atoms form covalent bonds where adjacent atoms share an electron. Electrons thus bound are not free to move and are not affected by an electric field. These bonds are fairly weak, and are easily broken. At any temperature above absolute zero, many of the bonds are broken leaving electrons free to move. So, as temperature increases, the semiconductor material becomes a better and better conductor. This is an intrinsic, or pure semiconductor. So, the above statement " Semiconductors are insulators at low temperatures and reasonably good conductors at higher temperatures." is absolutely true.As used in electronics, impurities are intentionally introduced (doped) into the semiconductor. When penta-valent (5 outer electrons) elements such as Arsenic and Antimony are used, the semiconductor has many free electrons, and is said to be n-type. If tri-valent (3-outer electrons) elements such as Boron, Gallium and Indium are used, the material is electron starved, and is said to be p-type. If we dope one side of a semiconductor block such that it is n-type, and the other side p-type, a so-called semiconductor junction is formed. This is the building block for all modern electronics such as the diode, transistor and integrated circuit (IC).
How much dope did the dope dealer deal when the dope dealer did deal dope?
1 dime bag,
What is a Dope Rider?
it means they "ride dope" or, AKA, USE dope
What are the street drugs that will cause you to fail a drug test showing use of Bar?
dope dope dope dope
What is the french word for dope?
As a drug, the word is the same ' dope' To smoke dope would be 'fumer de la dope'
Can extrinsic semiconductor conduct at 0 k?
Normally, no electron energy states exist in the band gap, the gap between the valence band and conduction band in a semiconductor. However, if we dope the semiconductor, i.e. add donor (n type) or acceptor (p type) atoms to it, we introduce new electron energy states in the band gap! Take for example silicon, in which we introduce phosphorus, which is a group V element and thus a donor atom. This will introduce extra filled electron states just below the conduction band. Now, this all happens at 0K, so no current can flow (this is logical as electrons don't move at this temperature, even with an electric field applied). But if we raise the temperature e.g. until room temperature at 300K, the electrons gain energy and can jump into the free energy states in the conduction band. These electrons in the conduction band can now conduct electricity.
How many valence electrons are there in doped materials of p-type and n-type materials?
1. N and P-type Semiconductors Neither pure silicon(Si) nor germanium(Ge) are great conductors. They form a crystal lattice by having each atom share all of its 4 valence electrons with neighbouring atoms. The total of eight electrons can not easily be jiggled out of place by an incoming current. If , however, the crystalline array is "doped"(mixed with an impurity) with arsenic which has five valence electrons, the behaviour of the lattice will change. Four bonds will be still be made but there will be a leftover electron that can wander through the crystal. This is called an n-type semiconductor. Boron can also be used to dope a pure crystal of silicon. But since boron only offers 3 of the four electrons that a silicon atom needs, each silicon center is left with a hole. Semiconductors made in this manner are called p-type. In a p-type material if an atom from a neighbouring atom fills the hole, it will leave a hole adjacent to it. This process will continue in a domino effect and the hole will be moving in the direction opposite to electron-flow. In reality the atoms are remaining fixed in the lattice, but there is an illusion that the holes are physically moving.
