Investigation On Damage Characteristics Of Element Under Composite Pulse Laser Irradiation

The study of the interaction between high-energy laser and monocrystalline silicon has important value in the application fields of laser micromachining,solar cells,photodetectors and integrated circuits.At present,all kinds of studies on the interaction between laser and monocrystalline silicon emerge in endlessly,and the study of the interaction between laser parameters and monocrystalline silicon provides a theoretical basis for people to expand the application demand of monocrystalline silicon and guide the processing technology of monocrystalline silicon.In recent years,the research on laser-induced monocrystalline silicon is mostly focused on single-wavelength pulsed laser,and the damage characteristics of multi-wavelength composite pulse and single-wavelength pulsed laser are also different.therefore,the study of the interaction between multi-wavelength composite pulse laser and monocrystalline silicon has high application value.Through the combination of numerical simulation and experimental verification,the interaction of 1064nm laser and 532nm laser and their combined irradiation on monocrystalline silicon is studied,and their damage characteristics are analyzed.Based on the theory of Fourier heat conduction and elasticity,the temperature field and stress field model of monocrystalline silicon irradiated by 1064nm and 532nm laser and their combination are established.The transient temperature field and thermal stress field of monocrystalline silicon irradiated by 1064nm,532nm laser and composite laser are simulated by finite element simulation software,and the variation rules of temperature field and stress field with laser energy are obtained.The damage radius and melting depth curves of monocrystalline silicon induced by 1064nm,532nm laser and composite laser are obtained.Among them,when the composite laser energy is constant,the energy ratio and delay time of the two pulses of laser also have some differences on the damage characteristics of monocrystalline silicon.When the energy ratio is different,when the energy proportion of 532nm laser increases,the damage radius and melting depth of monocrystalline silicon also increase.When the energy proportion of 1064nm laser increases,the damage radius and melting depth of monocrystalline silicon decrease.When there is no delay effect,the damage effect of composite laser irradiation on monocrystalline silicon is the greatest.When there is delay time,with the increase of delay time,the damage effect of monocrystalline silicon induced by composite laser decreases at first,then increases,and then decreases gradually.Finally,the damage experimental testing system of monocrystalline silicon was set up,and the damage experiments of monocrystalline silicon irradiated by 1064nm laser and 532nm laser and cumulative irradiation of 1064nm and 532nm laser were carried out respectively.The damage threshold energy of monocrystalline silicon irradiated by 1064nm and 532nm laser is obtained experimentally,and the change law of damage of monocrystalline silicon induced by 1064nm and 532nm laser is verified.The results show that in the damage study of monocrystalline silicon induced by nanosecond laser,monocrystalline silicon is mainly subjected to surface damage and stress damage,and composite laser can significantly improve the damage effect of monocrystalline silicon.The experimental results show that the damage threshold of 1064nm laser is 2.1J/cm2,and the laser damage threshold of 532nm is 0.20J/cm2.Among them,the damage effect of monocrystalline silicon induced by 532nm laser is the most obvious.With the increase of laser energy,the damage radius and melting damage depth of monocrystalline silicon increase.When the damage radius increases to a certain range,it tends to be stable,and the melting damage depth increases all the time.The variation rules of thermal melting damage radius and damage depth obtained by the experiment are basically consistent with the results obtained by the simulation model.