Ultrafast scanning tunneling microscopy using a photoexcited low-temperature-grown GaAs tip

Abstract

We report ultrafast scanning tunneling microscopy using a low-temperature-grown GaAs tip photoexcited by 100-fs, 800-nm pulses. We use this tip to detect picosecond transients on a coplanar stripline and demonstrate a temporal resolution of 1.7 ps. A dependence of the transient signal upon spatial position of the tip is revealed, indicating that the signal arises from areas on the sample smaller than ∼20nm.