Research on Charge Transfer Characteristics Induced by Laser Irradiation Monocrystalline Silicon

In order to study the charge characteristics of monocrystalline silicon irradiated by femtosecond pulsed laser, measurement systems of charge and infrared temperature induced by femtosecond pulse laser irradiation monocrystalline silicon are established by using oscilloscope and infrared thermal imager. The monocrystalline silicon (circle disc) irradiated by femtosecond pulse laser are carried out along the thickness direction of monocrystalline silicon. The experimental results show that the thermo-mechanical coupling effect of femtosecond pulsed laser irradiated on monocrystalline silicon will produce polarization in the target. At the initial stage of laser irradiation, the laser damage threshold of the interface between crystal surface and air is low and the charge mainly transfers along the surface of monocrystalline silicon, resulting in a high polarization. With the continuation of laser irradiation, it proves that the charge transfers in monocrystalline silicon gradually, and the polarization degree decreases with the modification of the material internal structure. After laser irradiation for a certain time, the charge transfers tend to be stable. Because the target lies in front of the laser focus, its energy density is insufficient to destroy the macrostructure of the target due to laser-pressure and temperature gradient, the polarization effect tends to be stable, resulting in a stable periodic change of charge transfer and recovery.