Detection of a Fermi level crossing in three-domainSi(111)−In(4×1)

Abstract

Using photoemission and inverse photoemission, it has recently been demonstrated that single domain $\mathrm{Si}(111)\ensuremath{-}\mathrm{In}(4\ifmmode\times\else\texttimes\fi{}1)$ overlayers possess a clear Fermi level crossing at $\ensuremath{\approx}0.6\ensuremath{\Gamma}X\ifmmode\bar\else\textasciimacron\fi{}.$ However, a previous inverse photoemission study, that was performed on a three domain sample, concluded that the overlayer was semiconducting. In an attempt to reconcile the results of the two inverse photoemission studies we proposed, in an earlier paper, that the first study did not probe the region of reciprocal space where the Fermi level crossing is now known to occur. In this paper we demonstrate that this suggestion is correct. Using a three domain $\mathrm{Si}(111)\ensuremath{-}\mathrm{In}(4\ifmmode\times\else\texttimes\fi{}1)$ overlayer, we mapped along the $\ensuremath{\Gamma}K\ifmmode\bar\else\textasciimacron\fi{}$ azimuth of the $1\ifmmode\times\else\texttimes\fi{}1$ zone, which is coincident with the $\ensuremath{\Gamma}X\ifmmode\bar\else\textasciimacron\fi{}$ azimuth of the $4\ifmmode\times\else\texttimes\fi{}1$ zone, with inverse photoemission, and found a Fermi level crossing at $\ensuremath{\approx}0.6\ensuremath{\Gamma}X\ifmmode\bar\else\textasciimacron\fi{}.$ We have now detected Fermi level crossings in both single and three domain $4\ifmmode\times\else\texttimes\fi{}1$ overlayers.