Investigation of Ultrafast Carrier Dynamics in Quantum Wire by Terahertz Time-Domain Spectroscopy

摘要

We have investigated ultrafast carrier dynamics in a semiconductor crescent-shaped quantum wire by terahertz (THz) wave time-domain spectroscopy (THz-TDS). THz waves are generated by the motion of photoexcited carriers in semiconductor nanostructures, so that the time evolution of coherent polarization in the nanostructures is obtained by integration of observed THz waves. THz waves were generated by ultrashort optical pulse excitation of the quantum wire and detected using a free-space electrooptic (EO) sampling method. The dephasing time of coherent polarization in the quantum wire was varied by increasing the excitation energy. It was estimated that the dephasing time of coherent polarization is 300 fs at an excitation energy of 1.534eV.