Measurement of phonon energy of Sb2Te3 by scanning tunneling microscope light-emission spectroscopy

• STM light emission spectroscopy combined with ps laser irradiation is presented.
• The phonon energy of A2u mode of Sb2Te3 was successfully determined.
• Phonons will be able to identified with spatial resolution of STM by this method.

We have measured the energy of the A2u phonon mode of Sb2Te3 by scanning tunneling microscope light-emission (STM-LE) spectroscopy combined with ps-pulsed laser irradiation of the STM tip-sample gap. It is known that the STM-LE from Sb2Te3 is excited by electronic transitions at a photon energy of around 1.6 eV, i.e, a single peak with a narrow spectral width appears at the photon energy in the STM-LE spectrum. For STM-LE occurring with the STM tip-sample gap irradiated by ps laser pulses, several supplementary peaks appear in the STM-LE spectra (in addition to the single original peak). The difference in energy between adjacent peaks gives the phonon energy of the A2u mode of Sb2Te3.