Probing subpicosecond dynamics using pulsed laser combined scanning tunneling microscopy

Time-resolved tunneling current measurement in the subpicosecond range was realized by ultrashort-pulse laser combined scanning tunneling microscopy, using the shaken-pulse-pair method. A low-temperature-grown GaNxAs1-x (x=0.36%) sample exhibited two ultrafast transient processes in the time-resolved tunnel current signal, whose lifetimes were determined to be 0.653+/-0.025 and 55.1+/-5.0 ps. These values are of the same order of magnitude as those measured in the conventional pump-probe reflectivity measurement. (C) 2004 American Institute of Physics.