Abstract
The ultrafast dynamic process in semiconductor Ge irradiated by the femtosecond laser pulses is numerically simulated on the basis of van Driel system. It is found that with the increase of depth, the carrier density and lattice temperature decrease, while the carrier temperature first increases and then drops. The laser fluence has a great influence on the ultrafast dynamical process in Ge. As the laser fluence remains a constant value, though the overall evolution of the carrier density and lattice temperature is almost independent of pulse duration and laser intensity, increasing the laser intensity will be more effective than increasing the pulse duration in the generation of carriers. Irradiating the Ge sample by the femtosecond double pulses, the ultrafast dynamical process of semiconductor can be affected by the temporal interval between the double pulses.
Highlights
The interaction between ultrashort laser pulses and semiconductor materials has been the hot topic in the past two decades and it has been well investigated both experimentally[1,2,3,4,5,6] and theoretically[6,7,8,9,10,11]
Since the photon energy is larger than the band gap of Ge, the electron will be excited from the valence band to conduction band when the Ge sample is irradiated by the laser pulse, and holes with the same quantity will be generated at the same time, thereby generating a great number of carrier pairs
Taken the semiconductor Ge as the research object, we simulate the energy transport process at the surface and interior of Ge which interacts with the femtosecond laser pulses
Summary
The interaction between ultrashort laser pulses and semiconductor materials has been the hot topic in the past two decades and it has been well investigated both experimentally[1,2,3,4,5,6] and theoretically[6,7,8,9,10,11]. The ultrafast dynamical process of semiconductor Ge irradiated by the femtosecond laser pulses is simulated by solving density-dependent two temperature model (DDTTM) proposed by van Driel[23,24,25]. To further investigate the effect of pulse duration on the ultrafast dynamical process of Ge, the femtosecond double-pulse technique is adopted in the end
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