Saturday, February 22, 2014

Look at the atom center initially had 4 electrons in its outer shell. Share one with his neighbor o

Computer Magic A - Physics of semiconductor | Lattice
Throughout the series we have seen how the major operating components manufactured semiconductor diode, BJT and MOSFET transistors. But we did not see why they behaved well. In this appendix we will explain.
We decided to take this discussion to an appendix, poljoinfo rather than leave it in the main body, for two reasons: It is not necessary to continue the series. Learn how transistors work was necessary to know how the components are built higher, but to know why not work the way it was. Requires a level physics and chemistry a little deeper poljoinfo than is required the rest of the series. You will not need to be an expert in electromagnetism, but words like current, voltage, electron, silicon or boron scare you. If you're confused, you should at least check Sieve Series on Electricity. It also requires that at least it sounds layered organization of the electrons of the atoms (I studied in high school, so I guess that is told in the ESO or the current school). It also requires you to assimilate each heading before moving to the next and remember. Finally, poljoinfo although not complicated, and will simplify poljoinfo so that is understandable, requires some mental agility, read it carefully and maybe read it twice to understand it.
Let's start our discussion by the silicon crystal. Silicon (Si) is an element with 14 protons and electrons 14, [1] divided into three layers: the first layer has 2 electrons, the second layer has 8 electrons and the third layer has four electrons. The silicon crystal are a lot of silicon atoms linked together by covalent bonds. Just in case you do not have fresh college chemistry: a covalent bond is one in which you two atoms pooled one electron each, sharing both, so that the electron is not one or the other, but both. Also worth remembering that the chemicals have fondness to fill its valence shell with 8 electrons, [2] whether dropping to spare so that the layer is empty (and therefore the penultimate, poljoinfo who is 8, becomes in "last" and complete left), either by taking poljoinfo the missing to be 8 in last. The covalent bond is a form of the shared electrons between two atoms, and so both have 8 (in a way, at least).
Look at the atom center initially had 4 electrons in its outer shell. Share one with his neighbor on the left, which in turn shares one with him, so that for every neighbor gains an electron ... in a way. And so, with 4 neighbors, its outer shell has 8 electrons want.
Obviously, in the real world is not a two-dimensional structure, but three-dimensional, so that is not a mesh, but two of the links are a bit up and two down a bit, and so bind the next 3D floor ... but hey, that does not matter. The important thing is: sicilio each atom is bonded to four neighbors via covalent bonds.
Let's see first the intrinsic semiconductor. We are not interested in our account, but we will see them over to shake them out of the way. Note that these electrons are strongly bound to the nuclei, so that this material, as such, is relatively poor conductor. But if that structure is energized (for example, simply by a high temperature, but can be other things), one of those electrons can jump from layer 3 to layer 4. Note that layer 4 is now farther from the nucleus, poljoinfo so that electron and is relatively free and can move along the material if we put a voltage ... ie as current flows. [3] Note: the material is insulator or conductor. It can be insulated in general, but if for example the temperature rises, it becomes conductive. It can also be, for example, because they arrive photons (ie, light).
Semiconductors that interest us, anyway, are extrinsic semiconductors. Suppose now that one of the atoms replace silicon by a phosphorous. In case you do not remember, phosphorus (P) has 15 electrons: 2 in the first layer, 8 in the second and 5 in the third. So when we introduce the strength of a network of silicon atoms form four covalent bonds with them ... and an electron is lost.
This electron is not part of any link. Not only that, but now all the atoms in both the silicon and the phosphorus have 8 electrons in the third layer. All are "complete". So that orphan electron is in the fourth poljoinfo layer.
Note that the element remains neutral, has a negative charge, because poljoinfo phosphorus has 15 protons, so that, from the point of v

No comments:

Post a Comment