Internal photoemission (IPE) spectroscopy is a powerful technique for investigating electronic properties at solid-solid interfaces. Upon photon excitation, electrons or/and holes in the solid under an external electrical bias, accumulate at the interface, escape over the energetic interfacial barrier, and produce an externally measured photocurrent. The onset of the photocurrent as a function of photon excitation energy indicates the energy barrier height as commonly used in the threshold spectroscopy. Furthermore, the characteristics of photoemission yield at the energies above (or possibly below) the barrier can also yield spectroscopic information. IPE has recently become an important tool used to determine the band offsets in metal oxide semiconductor structures. In this report, we will present a brief description of IPE principles and experimental setup and apply IPE to two important GaAs-based metal oxide semiconductor structures. These structures have become of prime research interest as potential structures in the next generation of electronic devices when the current silicon-based device downscaling comes to a halt.
Citation: Electrochemical Society Transactions
Pub Type: Journals
internal photoemission, interface energy barriers, photoconductivity, metal oxide semiconductors