Metal induced gap states at LiCl–Cu(0 0 1) interface studied by X-ray absorption fine structure

Abstract A single crystalline LiCl film grows heteroepitaxially on Cu(0 0 1) in a layer-by-layer fashion at 300 K. The LiCl–Cu(0 0 1) system provides a well-defined insulator–metal interface. Electronic structure of the LiCl film grown on Cu(0 0 1) was studied using Cl K-edge near edge X-ray absorption fine structure (NEXAFS). A pre-peak was observed on the bulk edge onset for the thin LiCl films. The pre-peak showed formation of metal-induced gap states (MIGS) in the band gap of LiCl. The characteristic decay length of the MIGS was determined to be 2.6 A by analyzing the thickness dependence on the intensity of the pre-peak. The present result has revealed the MIGS at the well-defined insulator–metal interface for the first time.