Effective mass of a two-dimensional √3 × √3 Ga single atomic layer on Si(111)

The effective mass of the empty conduction band surface state of a single atomic √3 × √3 Ga layer on Si(111) is determined using scanning tunneling spectra. The methodology is based on calculating the tunnel current using its dependence on the effective density of state mass and a parabolic band approximation followed by fitting to the measured tunneling spectra. An effective mass of meff,C = 0.59 ± 0.06 is obtained, in good agreement with a band structure calculation and inverse photo electron spectroscopy data.