What is the situation of sapphire crystal directional crystal growth

                                               What is the situation of sapphire crystal directional crystal growth

Sapphire crystal growth occurs at the solid-liquid interface. In order to ensure crystal grain growth, it is usually only necessary to make a small area of melt near the solid-liquid interface in the supercooled state, and most of the melt in the overheated state. The temperature of the grown crystal should be lower than Te. That is to say, the temperature of the whole system from melt to crystal changes from overheating to supercooling. The interface between the superheat and supercooled zone is an isothermal zone. The melt between this surface and the crystal growth interface is undercooled. The undercooling increases gradually along the opposite direction of crystal growth. The temperature of the crystal is low. This temperature gradient from crystal to melt is a necessary condition for heat transport. The heat is transferred from the melt to the crystal through the growth surface and transferred out of it.

Sapphire crystal material is a wide band gap direct band gap semiconductor ZnO crystal with wurtzite structure. The band gap width is 3.37 eV at room temperature. The exciton binding energy is 60 meV ³, which is much greater than the room temperature thermal ionization energy of 26 meV ³. ZnO with good optical properties has become a hot research material for photoelectric devices, such as gas sensors, piezoelectric sensors, transparent electrodes, short wavelength laser devices, ultraviolet light emitting diodes, transparent triodes, etc.

The improvement of sapphire crystal material and crucible adopts double motor structure to ensure stable low growth rate and rapid positioning of crucible and seed crystal. High performance motor without vibration and reducer with low noise are used to drive crystal and crucible to rise, which can provide stable low growth rate. The vacuum conditions of the equipment and the controllable inert gas flow under vacuum optimize the hot zone cleaning. Silicon oxide can be removed without polluting the crystal and crystal driving device.

The initial raw materials of sapphire crystal battery and polycrystalline battery are both primary polycrystalline silicon, which is similar to microcrystalline state. In order to have power generation capacity, it is necessary to make crystalline silicon from microcrystalline silicon, and the crystal orientation of crystalline silicon needs to be determined and controlled. Crystal growth is one of the processes that cannot be easily interchanged between single crystal cells and polycrystalline cells.