We investigate the electron-phonon (e-ph) interactions and carrier scattering in semiconductors that exhibit strongly anharmonic nuclear motion.
Materials of interest include three-dimensional and low-dimensional halide perovskites, organic crystals, and ionic crystals that favour six and eight-fold coordination structures (e.g. PbTe and TlBr, respectively).
Standard theories in semiconductor-physics were developed primarily for tetrahedrally bonded (i.e. diamond and Zinc-Blende) elemental (e.g. Si, Ge) and binary (e.g. GaAs, InP and CdTe) semiconductors.
The structural dynamics of tetrahedrally bonded crystals is captured reasonably well by perturbative treatments.
Therefore, analytical models for e-ph interactions in (quasi-)harmonic crystals describe their electronic properties very well.
However, the structural dynamics of the semiconductors we study is strongly anharmonic. Therefore, standard theory of e-ph interactions does not capture the experimental measurement of carrier mobilities and optical properties. Our experimental work provides new design rules toward new semiconductors with desired functionalities.