Valence band structure and effective masses of GaN(101¯0)

Abstract

The electronic structure of the clean and stoichiometric $\mathrm{GaN}(10\overline{1}0)$ cleavage surface is investigated in a comprehensive angle-resolved photoelectron spectroscopy study. A clear distinction between surface and bulk related features allows us to measure the dispersions of the occupied surface state band from the N dangling bonds as well as of the uppermost bulk valence bands and to extract the effective hole masses directly with high precision. This is performed along various directions in ${k}_{\ensuremath{\parallel}}$ space providing a detailed picture of the electronic band dispersion. The obtained results show three separated bulk bands without indications of a crossing of these bands as commonly predicted in theoretical works. Moreover, from the observed Fermi-level pinning we determine the position of the minimum of the empty Ga-derived surface state band, which is found deep within the fundamental band gap at $\ensuremath{\sim}2.3$ eV above the valence band maximum.