Weak current College】 【Semiconductor is how refrigeration.

<br> <br> Semiconductor refrigeration also called thermoelectric cooling, or thermoelectric cooling. It and the compression type, absorption, and other mechanical refrigeration in principle and equipment are different. Semiconductor refrigeration is the use of special semiconductor material, made of refrigeration devices ., direct cooling after power and therefore plays a thermoelectric cooling, it is a semiconductor technology in a special branch. In 1956, began to manufacture semiconductor cooling and made into a semiconductor cooler components and devices, briefly, how refrigeration of semiconductors., <br .> 1. Pearl posts effect: 1834, · France scientists Pearl posts first discovered the phenomenon of thermoelectric cooling and heating, ie metal song thermoelectric effect. <br> Consists of two different metals consisting of a pair of thermocouple, thermocouple in to DC current ., a couple of different sites, create endothermic and exothermic phenomenon, this phenomenon is known as the Pearl posts effect. But the metal's Pearl posts effect is weak because of refrigeration and heating on the left is of little practical value. Therefore, although more than .100 years ago have discovered this phenomenon, tP is experiencing to refrigeration, in the last 20 years, due to the development of semiconductor technology, semiconductor refrigeration technology into a new stage of the Foundation. This is because the semiconductor material Pearl posts more significant effect .. <br> <br> 2.N-type and P-type semiconductor: semiconductor cooler galvanic, is a specialized N-and p-type semiconductor. Any substance that is made of atoms, 'and then composed by a nucleus and electrons ., e-mail at very high speed around the Atomic Heng-Meng, and was attracted by the nucleus and thus subject to certain restrictions, electronic only in a few limited track running and cannot be any left. Atomic layer within the orbit of Electronics has .a different energy (known as electronic potential energy), the farthest away from the nucleus of the largest electronic energy, metals in the most outer orbit e, often from the nuclei of attracting between the atoms, the formation of the free movement of electronic, .electric field, you can participate in conducting such as copper, known as conductor. In the insulation, the e-mail is very difficult to leave the nucleus of attracting, cannot become free electrons, so they cannot participate in conducting such as rubber, etc .. Semiconductor capacity is of conductive conductor and an insulator. Semiconductor more important characteristics, to a certain number of some impurity doped semiconductor, not only can greatly increase the conductive capacities, but also with different types and quantities of the different nature, different uses of .semiconductor materials. Is a kind of impurities to produce semiconductor, free electrons, and of course increases the conductive. Blow up; this is called an n-type semiconductor semiconductors. As in a pure silicon to antimony to obtain an n-type semiconductor. .N-type semiconductor is an electrically conductive, this is the principle of conducting it. "" Another semiconductor called P-type semiconductor, it relied on the so-called "hole". to conductive. In the role of an external electric field, .null, "point of moving direction and electricity to flow in the opposite direction, that is, the hole is negative, the flow is being sung. This is a P-type semiconductor conductivity raw <br> Regardless of the N-type semiconductor in .free e-, or P-type semiconductor in the hole, they are involved in conducting, collectively, the "carrier", the "carrier". Conductive, 'is unique to semiconductors, as the result of mixing ratios of impurities. <br .> <br> Materials for semiconductor cooling, not only need N-and P-type semiconductor characteristics, but also according to the different doping, purposeful change thermoelectromotive rate of semiconductors, electrical conductivity and thermal conductivity, make this specialized semiconductor can meet the cooling .requirements. <br> 3. semiconductor refrigeration principle: put a P-type semiconductor and an N-type semiconductor, joins with copper plate welded together galvanic pair (Figure 2-15-1), when the DC current flows from the N- .type semiconductor P-type semiconductor, in 2, 3-on-chip copper join produces heat absorption phenomenon, this end-known as the cold end; but in I, 4-copper heat sink have joined, this end-known as the hot .end. If the current direction, in turn, the cold and hot-end will be interchangeable. As a couple on the thermoelectric effects are small (generally about 1kcal / h, depending on the component's size varies), practical is the dozens of galvanic .series, will cold end together, hot-end together, referred to thermoelectric figure <br> <br> tu1 <br> <br> When the cooling devices access a certain number of DC, cold end will gradually cooling down with a frosting; .while the temperature of the hot end and to gradually increase ambient heat. In order to clarify this, we can-2-15-2, roughly with carrier (electrons and holes) through the site (metal and semiconductor junction points) can change recovery .times. Because carriers in metal and semiconductor in potential energy size is different, so carriers in through the nodes, will inevitably lead to the transmission of energy. When the current polarity as in Figure 2-15-1, e-start from the power .supply anode by metal Ir nexus 4IF Yan-type semiconductor * node 3 * metal 'nexus 2, N-type semiconductor * node 1.' metal, back to the power of positive electrode. Because the left half of the P-type semiconductor, .conductive method is void, here have said before, the cavity flow direction and electronic flow in the opposite direction. So the hole is the node from the metal * 3 * P-type semiconductor * nexus 4 ·, metal, back to the power supply .anode. <br> Holes in metal with energy, lower than in P-type semiconductor in hole with energy. When electrons in the electric field, the metal through nexus 3 arrived at the P-type semiconductor, part energy must be increased, but .the hole itself is unable to increase energy, only from metal film absorb energy, and this part of the heat energy is converted into a hole of potential energy, therefore, in the nexus 3 metal slice is cooling down. When the hole along the P .-type semiconductor to node 4 flows to metal, because the P-type semiconductor energy greater than in the hole holes in metal, so the energy release excess energy and heat energy released, nexus 4 metal is heated., · <br> Figure 2 .-15-2 is in the right half of the N-type semiconductor and metal links rely on free electron conductive, and electronics in the center of potential energy less than gold, N-type semiconductor of potential energy in electronics. Under the influence of .electric current, e from metal by node 2 arrives at the N-typeSemiconductors, bound to increase the potential energy, this part of the potential energy can only be obtained from the metal heat, thus enabling nexus 2 metal cooling down. When an e- .mail from the n-type semiconductor after node 1 to gold at that time, the potential for electronics is relatively high local flow to potential energy is low, therefore releasing extra potential energy, and become a heat so that node 1 is the metal heating so .that the upper part of the metal cools down, become cold end; and the lower two join tablets are released, becoming the hot end. <br> When the power of positive and negative polarity reversed because electronic and cavitation flow direction is opposite with the .above, the hot and cold-end will be interchangeable. <br> To sum up, the semiconductor refrigeration endothermic and exothermic is determined by the carrier (electrons and holes) through the site, the potential energy of the arch 3 energy transfer, which .is the essence of semiconductor refrigeration. <br>.