Laser-induced band-bending variation on room-temperature CdTe(110)1 x 1 surfaces observed in photoemission and through the Franz-Keldish effect in surface differential reflectivity.

Abstract

A laser-induced band-bending variation on ultrahigh vacuum cleaved CdTe(110)1\ifmmode\times\else\texttimes\fi{}1 surfaces kept at room temperature has been observed both in angle-resolved photoelectron spectroscopy (ARPES) and, through the Franz-Keldish (FK) effect, in surface-differential reflectivity. Through ARPES spectra, the shift of the Fermi level, between the sample obscured and illuminated with an ${\mathrm{Ar}}^{+}$ laser power of 500 mW has been determined to be 0.2 eV. The FK effect has been observed at the ${\mathit{E}}_{0}$ bulk critical point and studied as a function of laser power, showing a linear increase in its oscillation amplitude up to a power of 400 mW. Upon switching off the laser, the FK effect disappears exponentially with a time constant of about 1300 s. A surface photovoltage induced by the helium lamp has also been observed.