Internal Photoemission Spectroscopy of Metal Gate∕High-k∕Semiconductor Interfaces

Internal photoemission (IPE) spectroscopy is a powerful technique for investigating electronic properties of inhomogeneous interfaces of hetero‐structures. Two of the most important aspects of IPE measurements involve threshold spectroscopy and photoelectron yield spectroscopy. In the first measurement type, IPE is used to determine the barrier heights at the interfaces while the second deals with photoemission of carriers (electrons and holes) with the energies above and below the barrier. We will present a brief description of the IPE principle upon which the extraction of the interfacial energy thresholds or barrier heights is based. The details of our IPE experiment setup will be also presented. For applications, in this report we will focus mainly on the first aspect of IPE where we determine the barrier heights of a technologically important class of materials which includes various metal‐high‐k insulator‐semiconductor structures.