NUMERICAL SIMULATIONS OF GERMANIUM NANOFILM UNDER FEMTOSECOND PULSE LASER HEATING
Femtosecond pulse laser heating of a germanium nanofilm is simulated by a method coupling the molecular dynamics and an energy transfer model for ultrafast laser interaction with semiconductors. Simulations demonstrate that the carrier temperature and density drastically evolve at the early heating time, while the lattice temperature gradually rises until the carrier-lattice thermal equilibrium is reached. The surface reflectivity dynamically changes as the carrier density evolves. The femtosecond laser heating can cause a strong thermal stress wave in the film. Initially, a compressive wave is yielded with the peak compression near the irradiated surface. Then, the compression wave transforms into a two-fold wave including compression and tension. At the rear film side, a strong tensile wave occurs with the maximum tension near the back surface. It is also found that shorter laser wavelength brings not only higher carrier temperature and density but also higher lattice temperature and larger thermal stresses.
Ultrashort pulse lasers Semiconductor Laser-matter interaction Numerical modeling
Yonggang SHEN Yong GAN
Department of Civil Engineering, Zhejiang University, Hangzhou 310058, China Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, China
国际会议
深圳
英文
150-153
2011-12-09（万方平台首次上网日期，不代表论文的发表时间）