Phase Resolved Infrared Imaging and Spectroscopy of Phonon Modes in A Wide-Bandgap Epitaxial Semiconductor

Abstract

In this thesis, the novel design of a Phase-Resolved Infrared Spectroscopy Microscope (PRISM) was described and constructed, then demonstrated to have an imaging spatial resolution of ~ 7.6 μm. The PRISM was placed within an asymmetric Michelson-based interferometer which allowed for pseudoheterodyne detection as well as Fourier Transform Infrared Spectroscopy (FTIR) of infrared reflection on a sample. Using PRISM, experimental data was collected consisting of reflectance images and spectroscopy of IR-active optical phonon modes in the tetragonal and orthorhombic phases of an epitaxial strontium stannate (SSO) sample at different incident light polarizations. The analysis and fitting process to determine the permittivity of the substrate and SSO thin film was then described and implemented. The analysis yielded the permittivity of the SSO film in the tetragonal and orthorhombic phases, providing new insight into the mobility-limiting phonon modes of epitaxial SSO.