Photoemission spectroscopy study of the charge accumulation at the K3Sb:Cs surface

The alkali antimonide compounds are widely applied in light detection devices. The strong optical absorption and the low electron affinity make the photon–electron conversion very efficient in these materials. In this paper, we present the results of a photoemission spectroscopy study of K3Sb films of 100 Å with and without an extra layer of 0.1 ml Cs. The shallow Sb 4d core levels show a chemical shift for K3Sb, which is only very slightly affected by the extra Cs layer. The results are explained as a consequence of charge accumulation at the K3Sb surface, which is induced by the Cs surface states.