Solar Power Battery Suede Production
Author: Source: Datetime: 2016-09-28 16:51:16
The production of monocrystalline silicon suede, the production of monocrystalline silicon suede is the use of monocrystalline silicon anisotropic etching, the surface of the wafer to form nano-level four-sided pyramidal structure.Electron microscope observation of monocrystalline silicon surface pyramid structure. Anisotropic corrosion, that is, the corrosion rate varies with the different crystal direction of the crystal, in general, the higher the covalent bond density between the crystal face, the more difficult the corrosion. For silicon,solar powered portable generator the (100) plane can be several times larger than the (111) plane etch rate, if a suitable etchant and corrosion temperature are selected. As a result, anisotropic etching of (100) silicon wafers eventually results in a tetrahedron pyramidal structure with many dense surfaces on the surface as the (111) plane.
The anisotropic etching solution for monocrystalline silicon is generally a hot alkaline solution, and the available bases are NaOH, KOH, LiOH, hydrazine, ethylenediamine and the like. Most of the use of cheap NaOH dilute solution (concentration of about 1%) to produce suede silicon, corrosion temperature of 70-85 ℃. In order to obtain a uniform suede, should also be added in the solution of alcohol (the most commonly used is ethanol and isopropyl alcohol) as a complexing agent to accelerate the corrosion of silicon. After corrosion of the suede, solar powered portable generator the general chemical cleaning. After the surface preparation of the wafers are not in the water for a long time, to prevent contamination, as soon as possible spread of the system.
Polysilicon suede production, polysilicon surface of the crystal surface structure is free to distribute, which makes alkaline corrosion is not very effective for polysilicon. Alkali corrosion on the different grains have different reaction rate of polycrystalline silicon surface to produce steps and cracks. In order to obtain a uniform suede structure, polysilicon suede preparation methods have been a lot of research, there are more prospects for the development of polycrystalline suede acid corroded suede mixture (HF, HNO3 and CH3COOH Reactive ion etching RIE, mechanical grooving and laser engraving.
Diffusion mechanism: Impurity ions in the semiconductor diffusion mechanism is more complex, the most simple can be divided into two main diffusion mechanism, substitution and gap diffusion.
The diffusion of boron and phosphorus in the silicon belongs to substitution diffusion. Ideally, the atomic arrangement of monocrystalline silicon has regular periodicity. At a certain temperature, the atom vibrates at its own equilibrium position. Due to the uneven thermal motion, atomic vibration is not uniform, some atoms will be due to vibration more powerful and out of their equilibrium position, solar powered portable generator moving to a new equilibrium position up, while in the original position to leave a " Quot; When the impurity atoms diffuse into the silicon crystal, they will first occupy these "space." In the crystal, because the thermal motion "space" is constantly moving in, so impurities can also be "vacant" movement to change their position in the crystal. This diffusion method is to replace the proliferation, it is only occupy the crystal "space", which is the normal lattice position, will not change the lattice structure. As the "vacancy" concentration increases with increasing temperature, so for the substitution of diffusion, the higher the temperature, the diffusion of atoms into the more impurity.
The diffusion of metals in silicon is mostly interstitial diffusion, such as nickel and magnesium. Crystal atoms in the interaction due to the existence of interstitial space, some impurities into the silicon crystal will move between the atomic gap of solar powered portable generator, successive jump forward, which is the gap-type diffusion. Impurity atoms in interstitial diffusion are moving in the interstitial space, and the energy required for gap diffusion is smaller than that in the substitutional diffusion, which needs to overcome the barrier transfer to the new equilibrium position. So in contrast, the gap-type diffusion rate than the substitution of diffusion speed faster.
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