The Research Of Polycrystalline Silicon Light Structure Ultrasonic Processing Method Based On The Fractal Geometry

The development and progress of the world is inseparable from energy consumption,the use of solar energy plays an important role in the development of new energy sources.It is clean,recyclable,the most important features is that it can be seen everywhere and has a large coverage.There are two kinds of form about solar power: Photovoltaic power generation and Concentrating Solar Power.Silicon is the main material of solar cells.There are two kinds of silicon: mono-crystalline silicon and polysilicon.In industrial production,the monocrystalline silicon's the application range is much smaller than polysilicon,because of its difficult preparation and the high cost.But polysilicon has a disadvantage: its absorption of sunlight is lower than the monocrystalline silicon.This difference is up to their own surface structure after texturing.The related study shows that applying ultrasonic standing wave field during the polysilicon etching can improve the structure of the polysilicon surface.The reason is that ultrasonic standing wave pushes the chemical particles to move to standing wave's node.This method makes the etching process more evenly distributed and to improve the light energy absorption of polysilicon effectively.In this paper,research is focused on creating a kind of ultrasonic machining method can be used for silicon surface processing.The surface structure produced by that method has fractal feature which can improve the light absorption rate,reduce the light reflection.In order to get the microstructure with the fractal feature,firstly need an innovative ultrasonic field to control chemical particles' movement.This paper designs two schemes to compare.(1)Design a multi-frequency superposition amplitude amplifier pole.And to use ANSYS for its modal analysis,observe and analyze the vibration under specific frequency.(2)Refer to the structure of ultrasonic phased array,to use different frequency chips to transducer ultrasonic energy and form a multi-frequency ultrasonic field.Show the graphics through the MATLB simulation.Finally,comparing the above two methods,to get the conclusion:(1)The vibration about horn is complex at particular frequency,during vibration the stress will be concentrated and broken easily.(2)The ultrasonic field's focus composite overlaid by wafer transducers in the first stage is not obvious in the MATLAB simulation results.So the next step is to use different frequency ultrasonic phased arrays to composite overlaid.(3)The simulation results of second stage show that this method can get sound pressure largetriangle focus area and pressure on both sides of the smaller triangle area which has two kinds of frequency ultrasonic.So the area is constructed of composite sound field provides the basic condition to subsequent other research.