Ultrafast Carriers Dynamics Of Aluminum-induced Nano-sized Crystallied Silicon Film Studied By Femtosecond Laser Technique

The combination of nanotechnology and biotechnology is becoming more and more mature,making the biological devices to the high-speed,miniaturization,large-capacity information storage of nano-biological devices gradually.Crystalline silicon is widely applied to traditional biological devices,because of its unique structure and characteristics,nano-sized silicon film can be a good substitute for crystalline silicon used in new type of nano-biological devices for speedier and more accurate.In this paper,aluminum-induced nano-sized crystallied silicon film was prepared by magnetron sputtering,and the ultrafast dynamics of surface carriers were studied by femtosecond laser pump-probe technique.The main research contents are as follows:(1)Aluminum-induced nano-sized crystallied silicon film was prepared by magnetron sputtering.The thickness was measured by using SGC-10 film thickness gauge.(2)The transient reflectivity change of crystalline silicon and the prepared aluminuminduced nano-sized crystallied silicon film were detected by using femtosecond pump-probe technique under different pump pulse energies.(3)Combining the experimental data,the whole decay process can be divided into two parts: fast decay and slow decay.By fitting the fast decay and slow decay processes with the bi-exponential model,the coefficient C of the bi-exponential model and the fast decay constant fτ are obtained.The fast decay process is mainly induced by carrier-carrier scattering and carrier-phonon scattering,and the slow decay process is induced by carrier recombination and carrier diffusion,the Auger recombination dominates the process effect.The diffusion model is established and the experimental data are fitted to verify the correctness of the conclusion.(4)The ultrafast dynamics of carriers under different pump pulse energies are compared and analyzed.It is concluded that the concentration of initial carriers,the rate of fast decay and the proportion of fast decay become larger,the time of fast decay becomes longer,the whole decay process becomes shorter with the pump energy increasing.(5)The ultrafast dynamics of surface carriers of aluminum-induced nano-sized crystallied silicon film and crystalline silicon under the sanme pump pulse energy are compared and analyzed.It is concluded that the decay process of aluminum-induced silicon films surface carriers is faster and the lowest point of carriers decay is closer to the initial value.